diff options
| -rw-r--r-- | drivers/gpu/drm/drm_dp_dual_mode_helper.c | 39 |
1 files changed, 32 insertions, 7 deletions
diff --git a/drivers/gpu/drm/drm_dp_dual_mode_helper.c b/drivers/gpu/drm/drm_dp_dual_mode_helper.c index 02a50929af67..e7f4fe2848a5 100644 --- a/drivers/gpu/drm/drm_dp_dual_mode_helper.c +++ b/drivers/gpu/drm/drm_dp_dual_mode_helper.c @@ -350,19 +350,44 @@ int drm_dp_dual_mode_set_tmds_output(enum drm_dp_dual_mode_type type, { uint8_t tmds_oen = enable ? 0 : DP_DUAL_MODE_TMDS_DISABLE; ssize_t ret; + int retry; if (type < DRM_DP_DUAL_MODE_TYPE2_DVI) return 0; - ret = drm_dp_dual_mode_write(adapter, DP_DUAL_MODE_TMDS_OEN, - &tmds_oen, sizeof(tmds_oen)); - if (ret) { - DRM_DEBUG_KMS("Failed to %s TMDS output buffers\n", - enable ? "enable" : "disable"); - return ret; + /* + * LSPCON adapters in low-power state may ignore the first write, so + * read back and verify the written value a few times. + */ + for (retry = 0; retry < 3; retry++) { + uint8_t tmp; + + ret = drm_dp_dual_mode_write(adapter, DP_DUAL_MODE_TMDS_OEN, + &tmds_oen, sizeof(tmds_oen)); + if (ret) { + DRM_DEBUG_KMS("Failed to %s TMDS output buffers (%d attempts)\n", + enable ? "enable" : "disable", + retry + 1); + return ret; + } + + ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_TMDS_OEN, + &tmp, sizeof(tmp)); + if (ret) { + DRM_DEBUG_KMS("I2C read failed during TMDS output buffer %s (%d attempts)\n", + enable ? "enabling" : "disabling", + retry + 1); + return ret; + } + + if (tmp == tmds_oen) + return 0; } - return 0; + DRM_DEBUG_KMS("I2C write value mismatch during TMDS output buffer %s\n", + enable ? "enabling" : "disabling"); + + return -EIO; } EXPORT_SYMBOL(drm_dp_dual_mode_set_tmds_output); |