From: Lyude Date: Wed, 13 Apr 2016 14:58:30 +0000 (-0400) Subject: drm/dp_helper: Always wait before retrying native aux transactions X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=e1083ff35157185b01bc0a99cb19b7cbae0fc9fa;p=linux-beck.git drm/dp_helper: Always wait before retrying native aux transactions This is part of a patch series to migrate all of the workarounds for commonly seen behavior from bad sinks in intel_dp_dpcd_read_wake() to drm's DP helper. Some sinks need some time during the process of resuming the system from sleep before they're ready to handle transactions. While it would be nice if they responded with NACKs in these scenarios, this isn't always the case as a few sinks will just timeout on all of the transactions they receive until they're ready. Signed-off-by: Lyude Tested-by: Ville Syrjälä Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/1460559513-32280-2-git-send-email-cpaul@redhat.com --- diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index df64ed1c0139..7dd330ae0e81 100644 --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -196,6 +196,10 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request, * sufficient, bump to 32 which makes Dell 4k monitors happier. */ for (retry = 0; retry < 32; retry++) { + if (err != 0 && err != -ETIMEDOUT) { + usleep_range(AUX_RETRY_INTERVAL, + AUX_RETRY_INTERVAL + 100); + } err = aux->transfer(aux, &msg); if (err < 0) { @@ -205,7 +209,6 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request, goto unlock; } - switch (msg.reply & DP_AUX_NATIVE_REPLY_MASK) { case DP_AUX_NATIVE_REPLY_ACK: if (err < size) @@ -215,10 +218,6 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request, case DP_AUX_NATIVE_REPLY_NACK: err = -EIO; goto unlock; - - case DP_AUX_NATIVE_REPLY_DEFER: - usleep_range(AUX_RETRY_INTERVAL, AUX_RETRY_INTERVAL + 100); - break; } }