drm/amd/display: set MSA MISC1 bit 6 while sending colorimetry in VSC SDP
[linux-2.6-microblaze.git] / drivers / gpu / drm / amd / display / modules / info_packet / info_packet.c
1 /*
2  * Copyright 2018 Advanced Micro Devices, Inc.
3  *
4  * Permission is hereby granted, free of charge, to any person obtaining a
5  * copy of this software and associated documentation files (the "Software"),
6  * to deal in the Software without restriction, including without limitation
7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8  * and/or sell copies of the Software, and to permit persons to whom the
9  * Software is furnished to do so, subject to the following conditions:
10  *
11  * The above copyright notice and this permission notice shall be included in
12  * all copies or substantial portions of the Software.
13  *
14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
17  * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
18  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
19  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
20  * OTHER DEALINGS IN THE SOFTWARE.
21  *
22  * Authors: AMD
23  *
24  */
25
26 #include "mod_info_packet.h"
27 #include "core_types.h"
28 #include "dc_types.h"
29 #include "mod_shared.h"
30 #include "mod_freesync.h"
31 #include "dc.h"
32
33 enum vsc_packet_revision {
34         vsc_packet_undefined = 0,
35         //01h = VSC SDP supports only 3D stereo.
36         vsc_packet_rev1 = 1,
37         //02h = 3D stereo + PSR.
38         vsc_packet_rev2 = 2,
39         //03h = 3D stereo + PSR2.
40         vsc_packet_rev3 = 3,
41         //04h = 3D stereo + PSR/PSR2 + Y-coordinate.
42         vsc_packet_rev4 = 4,
43         //05h = 3D stereo + PSR/PSR2 + Y-coordinate + Pixel Encoding/Colorimetry Format
44         vsc_packet_rev5 = 5,
45 };
46
47 #define HDMI_INFOFRAME_TYPE_VENDOR 0x81
48 #define HF_VSIF_VERSION 1
49
50 // VTEM Byte Offset
51 #define VTEM_PB0                0
52 #define VTEM_PB1                1
53 #define VTEM_PB2                2
54 #define VTEM_PB3                3
55 #define VTEM_PB4                4
56 #define VTEM_PB5                5
57 #define VTEM_PB6                6
58
59 #define VTEM_MD0                7
60 #define VTEM_MD1                8
61 #define VTEM_MD2                9
62 #define VTEM_MD3                10
63
64
65 // VTEM Byte Masks
66 //PB0
67 #define MASK_VTEM_PB0__RESERVED0  0x01
68 #define MASK_VTEM_PB0__SYNC       0x02
69 #define MASK_VTEM_PB0__VFR        0x04
70 #define MASK_VTEM_PB0__AFR        0x08
71 #define MASK_VTEM_PB0__DS_TYPE    0x30
72         //0: Periodic pseudo-static EM Data Set
73         //1: Periodic dynamic EM Data Set
74         //2: Unique EM Data Set
75         //3: Reserved
76 #define MASK_VTEM_PB0__END        0x40
77 #define MASK_VTEM_PB0__NEW        0x80
78
79 //PB1
80 #define MASK_VTEM_PB1__RESERVED1 0xFF
81
82 //PB2
83 #define MASK_VTEM_PB2__ORGANIZATION_ID 0xFF
84         //0: This is a Vendor Specific EM Data Set
85         //1: This EM Data Set is defined by This Specification (HDMI 2.1 r102.clean)
86         //2: This EM Data Set is defined by CTA-861-G
87         //3: This EM Data Set is defined by VESA
88 //PB3
89 #define MASK_VTEM_PB3__DATA_SET_TAG_MSB    0xFF
90 //PB4
91 #define MASK_VTEM_PB4__DATA_SET_TAG_LSB    0xFF
92 //PB5
93 #define MASK_VTEM_PB5__DATA_SET_LENGTH_MSB 0xFF
94 //PB6
95 #define MASK_VTEM_PB6__DATA_SET_LENGTH_LSB 0xFF
96
97
98
99 //PB7-27 (20 bytes):
100 //PB7 = MD0
101 #define MASK_VTEM_MD0__VRR_EN         0x01
102 #define MASK_VTEM_MD0__M_CONST        0x02
103 #define MASK_VTEM_MD0__RESERVED2      0x0C
104 #define MASK_VTEM_MD0__FVA_FACTOR_M1  0xF0
105
106 //MD1
107 #define MASK_VTEM_MD1__BASE_VFRONT    0xFF
108
109 //MD2
110 #define MASK_VTEM_MD2__BASE_REFRESH_RATE_98  0x03
111 #define MASK_VTEM_MD2__RB                    0x04
112 #define MASK_VTEM_MD2__RESERVED3             0xF8
113
114 //MD3
115 #define MASK_VTEM_MD3__BASE_REFRESH_RATE_07  0xFF
116
117 enum ColorimetryRGBDP {
118         ColorimetryRGB_DP_sRGB               = 0,
119         ColorimetryRGB_DP_AdobeRGB           = 3,
120         ColorimetryRGB_DP_P3                 = 4,
121         ColorimetryRGB_DP_CustomColorProfile = 5,
122         ColorimetryRGB_DP_ITU_R_BT2020RGB    = 6,
123 };
124 enum ColorimetryYCCDP {
125         ColorimetryYCC_DP_ITU601        = 0,
126         ColorimetryYCC_DP_ITU709        = 1,
127         ColorimetryYCC_DP_AdobeYCC      = 5,
128         ColorimetryYCC_DP_ITU2020YCC    = 6,
129         ColorimetryYCC_DP_ITU2020YCbCr  = 7,
130 };
131
132 void mod_build_vsc_infopacket(const struct dc_stream_state *stream,
133                 struct dc_info_packet *info_packet,
134                 bool *use_vsc_sdp_for_colorimetry)
135 {
136         unsigned int vsc_packet_revision = vsc_packet_undefined;
137         unsigned int i;
138         unsigned int pixelEncoding = 0;
139         unsigned int colorimetryFormat = 0;
140         bool stereo3dSupport = false;
141
142         /* Initialize first, later if infopacket is valid determine if VSC SDP
143          * should be used to signal colorimetry format and pixel encoding.
144          */
145         *use_vsc_sdp_for_colorimetry = false;
146
147         if (stream->timing.timing_3d_format != TIMING_3D_FORMAT_NONE && stream->view_format != VIEW_3D_FORMAT_NONE) {
148                 vsc_packet_revision = vsc_packet_rev1;
149                 stereo3dSupport = true;
150         }
151
152         /*VSC packet set to 2 when DP revision >= 1.2*/
153         if (stream->psr_version != 0)
154                 vsc_packet_revision = vsc_packet_rev2;
155
156         /* Update to revision 5 for extended colorimetry support for DPCD 1.4+ */
157         if (stream->link->dpcd_caps.dpcd_rev.raw >= 0x14 &&
158                         stream->link->dpcd_caps.dprx_feature.bits.VSC_SDP_COLORIMETRY_SUPPORTED)
159                 vsc_packet_revision = vsc_packet_rev5;
160
161         /* VSC packet not needed based on the features
162          * supported by this DP display
163          */
164         if (vsc_packet_revision == vsc_packet_undefined)
165                 return;
166
167         if (vsc_packet_revision == vsc_packet_rev2) {
168                 /* Secondary-data Packet ID = 0*/
169                 info_packet->hb0 = 0x00;
170                 /* 07h - Packet Type Value indicating Video
171                  * Stream Configuration packet
172                  */
173                 info_packet->hb1 = 0x07;
174                 /* 02h = VSC SDP supporting 3D stereo and PSR
175                  * (applies to eDP v1.3 or higher).
176                  */
177                 info_packet->hb2 = 0x02;
178                 /* 08h = VSC packet supporting 3D stereo + PSR
179                  * (HB2 = 02h).
180                  */
181                 info_packet->hb3 = 0x08;
182
183                 for (i = 0; i < 28; i++)
184                         info_packet->sb[i] = 0;
185
186                 info_packet->valid = true;
187         }
188
189         if (vsc_packet_revision == vsc_packet_rev1) {
190
191                 info_packet->hb0 = 0x00;        // Secondary-data Packet ID = 0
192                 info_packet->hb1 = 0x07;        // 07h = Packet Type Value indicating Video Stream Configuration packet
193                 info_packet->hb2 = 0x01;        // 01h = Revision number. VSC SDP supporting 3D stereo only
194                 info_packet->hb3 = 0x01;        // 01h = VSC SDP supporting 3D stereo only (HB2 = 01h).
195
196                 info_packet->valid = true;
197         }
198
199         if (stereo3dSupport) {
200                 /* ==============================================================================================================|
201                  * A. STEREO 3D
202                  * ==============================================================================================================|
203                  * VSC Payload (1 byte) From DP1.2 spec
204                  *
205                  * Bits 3:0 (Stereo Interface Method Code)  |  Bits 7:4 (Stereo Interface Method Specific Parameter)
206                  * -----------------------------------------------------------------------------------------------------
207                  * 0 = Non Stereo Video                     |  Must be set to 0x0
208                  * -----------------------------------------------------------------------------------------------------
209                  * 1 = Frame/Field Sequential               |  0x0: L + R view indication based on MISC1 bit 2:1
210                  *                                          |  0x1: Right when Stereo Signal = 1
211                  *                                          |  0x2: Left when Stereo Signal = 1
212                  *                                          |  (others reserved)
213                  * -----------------------------------------------------------------------------------------------------
214                  * 2 = Stacked Frame                        |  0x0: Left view is on top and right view on bottom
215                  *                                          |  (others reserved)
216                  * -----------------------------------------------------------------------------------------------------
217                  * 3 = Pixel Interleaved                    |  0x0: horiz interleaved, right view pixels on even lines
218                  *                                          |  0x1: horiz interleaved, right view pixels on odd lines
219                  *                                          |  0x2: checker board, start with left view pixel
220                  *                                          |  0x3: vertical interleaved, start with left view pixels
221                  *                                          |  0x4: vertical interleaved, start with right view pixels
222                  *                                          |  (others reserved)
223                  * -----------------------------------------------------------------------------------------------------
224                  * 4 = Side-by-side                         |  0x0: left half represents left eye view
225                  *                                          |  0x1: left half represents right eye view
226                  */
227                 switch (stream->timing.timing_3d_format) {
228                 case TIMING_3D_FORMAT_HW_FRAME_PACKING:
229                 case TIMING_3D_FORMAT_SW_FRAME_PACKING:
230                 case TIMING_3D_FORMAT_TOP_AND_BOTTOM:
231                 case TIMING_3D_FORMAT_TB_SW_PACKED:
232                         info_packet->sb[0] = 0x02; // Stacked Frame, Left view is on top and right view on bottom.
233                         break;
234                 case TIMING_3D_FORMAT_DP_HDMI_INBAND_FA:
235                 case TIMING_3D_FORMAT_INBAND_FA:
236                         info_packet->sb[0] = 0x01; // Frame/Field Sequential, L + R view indication based on MISC1 bit 2:1
237                         break;
238                 case TIMING_3D_FORMAT_SIDE_BY_SIDE:
239                 case TIMING_3D_FORMAT_SBS_SW_PACKED:
240                         info_packet->sb[0] = 0x04; // Side-by-side
241                         break;
242                 default:
243                         info_packet->sb[0] = 0x00; // No Stereo Video, Shall be cleared to 0x0.
244                         break;
245                 }
246
247         }
248
249         /* 05h = VSC SDP supporting 3D stereo, PSR2, and Pixel Encoding/Colorimetry Format indication.
250          *   Added in DP1.3, a DP Source device is allowed to indicate the pixel encoding/colorimetry
251          *   format to the DP Sink device with VSC SDP only when the DP Sink device supports it
252          *   (i.e., VSC_SDP_EXTENSION_FOR_COLORIMETRY_SUPPORTED bit in the DPRX_FEATURE_ENUMERATION_LIST
253          *   register (DPCD Address 02210h, bit 3) is set to 1).
254          *   (Requires VSC_SDP_EXTENSION_FOR_COLORIMETRY_SUPPORTED bit set to 1 in DPCD 02210h. This
255          *   DPCD register is exposed in the new Extended Receiver Capability field for DPCD Rev. 1.4
256          *   (and higher). When MISC1. bit 6. is Set to 1, a Source device uses a VSC SDP to indicate
257          *   the Pixel Encoding/Colorimetry Format and that a Sink device must ignore MISC1, bit 7, and
258          *   MISC0, bits 7:1 (MISC1, bit 7. and MISC0, bits 7:1 become "don't care").)
259          */
260         if (vsc_packet_revision == vsc_packet_rev5) {
261                 /* Secondary-data Packet ID = 0 */
262                 info_packet->hb0 = 0x00;
263                 /* 07h - Packet Type Value indicating Video Stream Configuration packet */
264                 info_packet->hb1 = 0x07;
265                 /* 05h = VSC SDP supporting 3D stereo, PSR2, and Pixel Encoding/Colorimetry Format indication. */
266                 info_packet->hb2 = 0x05;
267                 /* 13h = VSC SDP supporting 3D stereo, + PSR2, + Pixel Encoding/Colorimetry Format indication (HB2 = 05h). */
268                 info_packet->hb3 = 0x13;
269
270                 info_packet->valid = true;
271
272                 /* If we are using VSC SDP revision 05h, use this to signal for
273                  * colorimetry format and pixel encoding. HW should later be
274                  * programmed to set MSA MISC1 bit 6 to indicate ignore
275                  * colorimetry format and pixel encoding in the MSA.
276                  */
277                 *use_vsc_sdp_for_colorimetry = true;
278
279                 /* Set VSC SDP fields for pixel encoding and colorimetry format from DP 1.3 specs
280                  * Data Bytes DB 18~16
281                  * Bits 3:0 (Colorimetry Format)        |  Bits 7:4 (Pixel Encoding)
282                  * ----------------------------------------------------------------------------------------------------
283                  * 0x0 = sRGB                           |  0 = RGB
284                  * 0x1 = RGB Wide Gamut Fixed Point
285                  * 0x2 = RGB Wide Gamut Floating Point
286                  * 0x3 = AdobeRGB
287                  * 0x4 = DCI-P3
288                  * 0x5 = CustomColorProfile
289                  * (others reserved)
290                  * ----------------------------------------------------------------------------------------------------
291                  * 0x0 = ITU-R BT.601                   |  1 = YCbCr444
292                  * 0x1 = ITU-R BT.709
293                  * 0x2 = xvYCC601
294                  * 0x3 = xvYCC709
295                  * 0x4 = sYCC601
296                  * 0x5 = AdobeYCC601
297                  * 0x6 = ITU-R BT.2020 Y'cC'bcC'rc
298                  * 0x7 = ITU-R BT.2020 Y'C'bC'r
299                  * (others reserved)
300                  * ----------------------------------------------------------------------------------------------------
301                  * 0x0 = ITU-R BT.601                   |  2 = YCbCr422
302                  * 0x1 = ITU-R BT.709
303                  * 0x2 = xvYCC601
304                  * 0x3 = xvYCC709
305                  * 0x4 = sYCC601
306                  * 0x5 = AdobeYCC601
307                  * 0x6 = ITU-R BT.2020 Y'cC'bcC'rc
308                  * 0x7 = ITU-R BT.2020 Y'C'bC'r
309                  * (others reserved)
310                  * ----------------------------------------------------------------------------------------------------
311                  * 0x0 = ITU-R BT.601                   |  3 = YCbCr420
312                  * 0x1 = ITU-R BT.709
313                  * 0x2 = xvYCC601
314                  * 0x3 = xvYCC709
315                  * 0x4 = sYCC601
316                  * 0x5 = AdobeYCC601
317                  * 0x6 = ITU-R BT.2020 Y'cC'bcC'rc
318                  * 0x7 = ITU-R BT.2020 Y'C'bC'r
319                  * (others reserved)
320                  * ----------------------------------------------------------------------------------------------------
321                  * 0x0 =DICOM Part14 Grayscale          |  4 = Yonly
322                  * Display Function
323                  * (others reserved)
324                  */
325
326                 /* Set Pixel Encoding */
327                 switch (stream->timing.pixel_encoding) {
328                 case PIXEL_ENCODING_RGB:
329                         pixelEncoding = 0x0;  /* RGB = 0h */
330                         break;
331                 case PIXEL_ENCODING_YCBCR444:
332                         pixelEncoding = 0x1;  /* YCbCr444 = 1h */
333                         break;
334                 case PIXEL_ENCODING_YCBCR422:
335                         pixelEncoding = 0x2;  /* YCbCr422 = 2h */
336                         break;
337                 case PIXEL_ENCODING_YCBCR420:
338                         pixelEncoding = 0x3;  /* YCbCr420 = 3h */
339                         break;
340                 default:
341                         pixelEncoding = 0x0;  /* default RGB = 0h */
342                         break;
343                 }
344
345                 /* Set Colorimetry format based on pixel encoding */
346                 switch (stream->timing.pixel_encoding) {
347                 case PIXEL_ENCODING_RGB:
348                         if ((stream->output_color_space == COLOR_SPACE_SRGB) ||
349                                         (stream->output_color_space == COLOR_SPACE_SRGB_LIMITED))
350                                 colorimetryFormat = ColorimetryRGB_DP_sRGB;
351                         else if (stream->output_color_space == COLOR_SPACE_ADOBERGB)
352                                 colorimetryFormat = ColorimetryRGB_DP_AdobeRGB;
353                         else if ((stream->output_color_space == COLOR_SPACE_2020_RGB_FULLRANGE) ||
354                                         (stream->output_color_space == COLOR_SPACE_2020_RGB_LIMITEDRANGE))
355                                 colorimetryFormat = ColorimetryRGB_DP_ITU_R_BT2020RGB;
356                         break;
357
358                 case PIXEL_ENCODING_YCBCR444:
359                 case PIXEL_ENCODING_YCBCR422:
360                 case PIXEL_ENCODING_YCBCR420:
361                         /* Note: xvYCC probably not supported correctly here on DP since colorspace translation
362                          * loses distinction between BT601 vs xvYCC601 in translation
363                          */
364                         if (stream->output_color_space == COLOR_SPACE_YCBCR601)
365                                 colorimetryFormat = ColorimetryYCC_DP_ITU601;
366                         else if (stream->output_color_space == COLOR_SPACE_YCBCR709)
367                                 colorimetryFormat = ColorimetryYCC_DP_ITU709;
368                         else if (stream->output_color_space == COLOR_SPACE_ADOBERGB)
369                                 colorimetryFormat = ColorimetryYCC_DP_AdobeYCC;
370                         else if (stream->output_color_space == COLOR_SPACE_2020_YCBCR)
371                                 colorimetryFormat = ColorimetryYCC_DP_ITU2020YCbCr;
372                         break;
373
374                 default:
375                         colorimetryFormat = ColorimetryRGB_DP_sRGB;
376                         break;
377                 }
378
379                 info_packet->sb[16] = (pixelEncoding << 4) | colorimetryFormat;
380
381                 /* Set color depth */
382                 switch (stream->timing.display_color_depth) {
383                 case COLOR_DEPTH_666:
384                         /* NOTE: This is actually not valid for YCbCr pixel encoding to have 6 bpc
385                          *       as of DP1.4 spec, but value of 0 probably reserved here for potential future use.
386                          */
387                         info_packet->sb[17] = 0;
388                         break;
389                 case COLOR_DEPTH_888:
390                         info_packet->sb[17] = 1;
391                         break;
392                 case COLOR_DEPTH_101010:
393                         info_packet->sb[17] = 2;
394                         break;
395                 case COLOR_DEPTH_121212:
396                         info_packet->sb[17] = 3;
397                         break;
398                 /*case COLOR_DEPTH_141414: -- NO SUCH FORMAT IN DP SPEC */
399                 case COLOR_DEPTH_161616:
400                         info_packet->sb[17] = 4;
401                         break;
402                 default:
403                         info_packet->sb[17] = 0;
404                         break;
405                 }
406
407                 /* all YCbCr are always limited range */
408                 if ((stream->output_color_space == COLOR_SPACE_SRGB_LIMITED) ||
409                                 (stream->output_color_space == COLOR_SPACE_2020_RGB_LIMITEDRANGE) ||
410                                 (pixelEncoding != 0x0)) {
411                         info_packet->sb[17] |= 0x80; /* DB17 bit 7 set to 1 for CEA timing. */
412                 }
413
414                 /* Content Type (Bits 2:0)
415                  *  0 = Not defined.
416                  *  1 = Graphics.
417                  *  2 = Photo.
418                  *  3 = Video.
419                  *  4 = Game.
420                  */
421                 info_packet->sb[18] = 0;
422         }
423 }
424
425 /**
426  *****************************************************************************
427  *  Function: mod_build_hf_vsif_infopacket
428  *
429  *  @brief
430  *     Prepare HDMI Vendor Specific info frame.
431  *     Follows HDMI Spec to build up Vendor Specific info frame
432  *
433  *  @param [in] stream: contains data we may need to construct VSIF (i.e. timing_3d_format, etc.)
434  *  @param [out] info_packet:   output structure where to store VSIF
435  *****************************************************************************
436  */
437 void mod_build_hf_vsif_infopacket(const struct dc_stream_state *stream,
438                 struct dc_info_packet *info_packet, int ALLMEnabled, int ALLMValue)
439 {
440                 unsigned int length = 5;
441                 bool hdmi_vic_mode = false;
442                 uint8_t checksum = 0;
443                 uint32_t i = 0;
444                 enum dc_timing_3d_format format;
445                 bool bALLM = (bool)ALLMEnabled;
446                 bool bALLMVal = (bool)ALLMValue;
447
448                 info_packet->valid = false;
449                 format = stream->timing.timing_3d_format;
450                 if (stream->view_format == VIEW_3D_FORMAT_NONE)
451                         format = TIMING_3D_FORMAT_NONE;
452
453                 if (stream->timing.hdmi_vic != 0
454                                 && stream->timing.h_total >= 3840
455                                 && stream->timing.v_total >= 2160
456                                 && format == TIMING_3D_FORMAT_NONE)
457                         hdmi_vic_mode = true;
458
459                 if ((format == TIMING_3D_FORMAT_NONE) && !hdmi_vic_mode && !bALLM)
460                         return;
461
462                 info_packet->sb[1] = 0x03;
463                 info_packet->sb[2] = 0x0C;
464                 info_packet->sb[3] = 0x00;
465
466                 if (bALLM) {
467                         info_packet->sb[1] = 0xD8;
468                         info_packet->sb[2] = 0x5D;
469                         info_packet->sb[3] = 0xC4;
470                         info_packet->sb[4] = HF_VSIF_VERSION;
471                 }
472
473                 if (format != TIMING_3D_FORMAT_NONE)
474                         info_packet->sb[4] = (2 << 5);
475
476                 else if (hdmi_vic_mode)
477                         info_packet->sb[4] = (1 << 5);
478
479                 switch (format) {
480                 case TIMING_3D_FORMAT_HW_FRAME_PACKING:
481                 case TIMING_3D_FORMAT_SW_FRAME_PACKING:
482                         info_packet->sb[5] = (0x0 << 4);
483                         break;
484
485                 case TIMING_3D_FORMAT_SIDE_BY_SIDE:
486                 case TIMING_3D_FORMAT_SBS_SW_PACKED:
487                         info_packet->sb[5] = (0x8 << 4);
488                         length = 6;
489                         break;
490
491                 case TIMING_3D_FORMAT_TOP_AND_BOTTOM:
492                 case TIMING_3D_FORMAT_TB_SW_PACKED:
493                         info_packet->sb[5] = (0x6 << 4);
494                         break;
495
496                 default:
497                         break;
498                 }
499
500                 if (hdmi_vic_mode)
501                         info_packet->sb[5] = stream->timing.hdmi_vic;
502
503                 info_packet->hb0 = HDMI_INFOFRAME_TYPE_VENDOR;
504                 info_packet->hb1 = 0x01;
505                 info_packet->hb2 = (uint8_t) (length);
506
507                 if (bALLM)
508                         info_packet->sb[5] = (info_packet->sb[5] & ~0x02) | (bALLMVal << 1);
509
510                 checksum += info_packet->hb0;
511                 checksum += info_packet->hb1;
512                 checksum += info_packet->hb2;
513
514                 for (i = 1; i <= length; i++)
515                         checksum += info_packet->sb[i];
516
517                 info_packet->sb[0] = (uint8_t) (0x100 - checksum);
518
519                 info_packet->valid = true;
520 }
521