usb: gadget: uvc: configfs: Add bFormatIndex attributes

The UVC format description are numbered using the descriptor's
bFormatIndex field. The index is used in UVC requests, and is thus
needed to handle requests in userspace. Make it dynamically discoverable
by exposing it in a bFormatIndex configfs attribute of the uncompressed
and mjpeg format config items.

The bFormatIndex value exposed through the attribute is stored in the
config item private data. However, that value is never set: the driver
instead computes the bFormatIndex value when linking the stream class
header in the configfs hierarchy and stores it directly in the class
descriptors in a separate structure. In order to expose the value
through the configfs attribute, store it in the config item private data
as well. This results in a small code simplification.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

diff --git a/Documentation/ABI/testing/configfs-usb-gadget-uvc b/Documentation/ABI/testing/configfs-usb-gadget-uvc
index 490a013..a6cc8d6 100644 (file)
--- a/Documentation/ABI/testing/configfs-usb-gadget-uvc
+++ b/Documentation/ABI/testing/configfs-usb-gadget-uvc
@@ -168,6 +168,10 @@ Description:       Specific MJPEG format descriptors
 
                All attributes read only,
                except bmaControls and bDefaultFrameIndex:
+               bFormatIndex            - unique id for this format descriptor;
+                                       only defined after parent header is
+                                       linked into the streaming class;
+                                       read-only
                bmaControls             - this format's data for bmaControls in
                                        the streaming header
                bmInterfaceFlags        - specifies interlace information,
@@ -212,6 +216,10 @@ Date:              Dec 2014
 KernelVersion: 4.0
 Description:   Specific uncompressed format descriptors
 
+               bFormatIndex            - unique id for this format descriptor;
+                                       only defined after parent header is
+                                       linked into the streaming class;
+                                       read-only
                bmaControls             - this format's data for bmaControls in
                                        the streaming header
                bmInterfaceFlags        - specifies interlace information,

diff --git a/drivers/usb/gadget/function/uvc_configfs.c b/drivers/usb/gadget/function/uvc_configfs.c
index fa8d2e1..5cee8ac 100644 (file)
--- a/drivers/usb/gadget/function/uvc_configfs.c
+++ b/drivers/usb/gadget/function/uvc_configfs.c
@@ -1538,6 +1538,7 @@ UVC_ATTR(uvcg_uncompressed_, cname, aname);
 
 #define identity_conv(x) (x)
 
+UVCG_UNCOMPRESSED_ATTR_RO(b_format_index, bFormatIndex, identity_conv);
 UVCG_UNCOMPRESSED_ATTR(b_bits_per_pixel, bBitsPerPixel, identity_conv);
 UVCG_UNCOMPRESSED_ATTR(b_default_frame_index, bDefaultFrameIndex,
                       identity_conv);
@@ -1568,6 +1569,7 @@ uvcg_uncompressed_bma_controls_store(struct config_item *item,
 UVC_ATTR(uvcg_uncompressed_, bma_controls, bmaControls);
 
 static struct configfs_attribute *uvcg_uncompressed_attrs[] = {
+       &uvcg_uncompressed_attr_b_format_index,
        &uvcg_uncompressed_attr_guid_format,
        &uvcg_uncompressed_attr_b_bits_per_pixel,
        &uvcg_uncompressed_attr_b_default_frame_index,
@@ -1738,6 +1740,7 @@ UVC_ATTR(uvcg_mjpeg_, cname, aname)
 
 #define identity_conv(x) (x)
 
+UVCG_MJPEG_ATTR_RO(b_format_index, bFormatIndex, identity_conv);
 UVCG_MJPEG_ATTR(b_default_frame_index, bDefaultFrameIndex,
                       identity_conv);
 UVCG_MJPEG_ATTR_RO(bm_flags, bmFlags, identity_conv);
@@ -1768,6 +1771,7 @@ uvcg_mjpeg_bma_controls_store(struct config_item *item,
 UVC_ATTR(uvcg_mjpeg_, bma_controls, bmaControls);
 
 static struct configfs_attribute *uvcg_mjpeg_attrs[] = {
+       &uvcg_mjpeg_attr_b_format_index,
        &uvcg_mjpeg_attr_b_default_frame_index,
        &uvcg_mjpeg_attr_bm_flags,
        &uvcg_mjpeg_attr_b_aspect_ratio_x,
@@ -2079,24 +2083,22 @@ static int __uvcg_fill_strm(void *priv1, void *priv2, void *priv3, int n,
                struct uvcg_format *fmt = priv1;
 
                if (fmt->type == UVCG_UNCOMPRESSED) {
-                       struct uvc_format_uncompressed *unc = *dest;
                        struct uvcg_uncompressed *u =
                                container_of(fmt, struct uvcg_uncompressed,
                                             fmt);
 
+                       u->desc.bFormatIndex = n + 1;
+                       u->desc.bNumFrameDescriptors = fmt->num_frames;
                        memcpy(*dest, &u->desc, sizeof(u->desc));
                        *dest += sizeof(u->desc);
-                       unc->bNumFrameDescriptors = fmt->num_frames;
-                       unc->bFormatIndex = n + 1;
                } else if (fmt->type == UVCG_MJPEG) {
-                       struct uvc_format_mjpeg *mjp = *dest;
                        struct uvcg_mjpeg *m =
                                container_of(fmt, struct uvcg_mjpeg, fmt);
 
+                       m->desc.bFormatIndex = n + 1;
+                       m->desc.bNumFrameDescriptors = fmt->num_frames;
                        memcpy(*dest, &m->desc, sizeof(m->desc));
                        *dest += sizeof(m->desc);
-                       mjp->bNumFrameDescriptors = fmt->num_frames;
-                       mjp->bFormatIndex = n + 1;
                } else {
                        return -EINVAL;
                }