From e1083ff35157185b01bc0a99cb19b7cbae0fc9fa Mon Sep 17 00:00:00 2001 From: Lyude Date: Wed, 13 Apr 2016 10:58:30 -0400 Subject: [PATCH] drm/dp_helper: Always wait before retrying native aux transactions MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 --- drivers/gpu/drm/drm_dp_helper.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index df64ed1..7dd330a 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; } } -- 2.7.4