drm/amd/display: Increase timeout threshold for DMCUB reset

[Why]
If we're backdoor loading the DMCUB performs more work than just
the PHY reset so we can end up resetting before the cleanup has fully
finished.

[How]
Increase timeout, add udelay between spins to guarantee a minimum.

Reviewed-by: Roy Chan <roy.chan@amd.com>
Reviewed-by: Eric Yang <Eric.Yang2@amd.com>
Acked-by: Anson Jacob <Anson.Jacob@amd.com>
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/display/dmub/src/dmub_dcn31.c b/drivers/gpu/drm/amd/display/dmub/src/dmub_dcn31.c
index 19141bf..fc667cb 100644 (file)
--- a/drivers/gpu/drm/amd/display/dmub/src/dmub_dcn31.c
+++ b/drivers/gpu/drm/amd/display/dmub/src/dmub_dcn31.c
@@ -83,7 +83,7 @@ static inline void dmub_dcn31_translate_addr(const union dmub_addr *addr_in,
 void dmub_dcn31_reset(struct dmub_srv *dmub)
 {
        union dmub_gpint_data_register cmd;
-       const uint32_t timeout = 30;
+       const uint32_t timeout = 100;
        uint32_t in_reset, scratch, i;
 
        REG_GET(DMCUB_CNTL2, DMCUB_SOFT_RESET, &in_reset);
@@ -98,21 +98,21 @@ void dmub_dcn31_reset(struct dmub_srv *dmub)
                /**
                 * Timeout covers both the ACK and the wait
                 * for remaining work to finish.
-                *
-                * This is mostly bound by the PHY disable sequence.
-                * Each register check will be greater than 1us, so
-                * don't bother using udelay.
                 */
 
                for (i = 0; i < timeout; ++i) {
                        if (dmub->hw_funcs.is_gpint_acked(dmub, cmd))
                                break;
+
+                       udelay(1);
                }
 
                for (i = 0; i < timeout; ++i) {
                        scratch = dmub->hw_funcs.get_gpint_response(dmub);
                        if (scratch == DMUB_GPINT__STOP_FW_RESPONSE)
                                break;
+
+                       udelay(1);
                }
 
                /* Force reset in case we timed out, DMCUB is likely hung. */