This patch fixes a regression introduced between 2.6.39 & 3.1-rc1 whereby the displayport AUX channel stopped re-trying commands that elicited a DEFER response.
Signed-off-by: Brad Campbell brad@fnarfbargle.com
diff --git a/drivers/gpu/drm/radeon/atombios_dp.c b/drivers/gpu/drm/radeon/atombios_dp.c index 7ad43c6..b8450f4 100644 --- a/drivers/gpu/drm/radeon/atombios_dp.c +++ b/drivers/gpu/drm/radeon/atombios_dp.c @@ -60,11 +60,13 @@ static int radeon_process_aux_ch(struct radeon_i2c_chan *chan, int index = GetIndexIntoMasterTable(COMMAND, ProcessAuxChannelTransaction); unsigned char *base; int recv_bytes; + int retry_count = 0;
memset(&args, 0, sizeof(args));
base = (unsigned char *)rdev->mode_info.atom_context->scratch;
+retry: memcpy(base, send, send_bytes);
args.v1.lpAuxRequest = 0; @@ -79,6 +81,16 @@ static int radeon_process_aux_ch(struct radeon_i2c_chan *chan,
*ack = args.v1.ucReplyStatus;
+ /* defer */ + if (args.v1.ucReplyStatus == 0x20){ + DRM_DEBUG_KMS("dp_aux_ch defer\n"); + /* 10 is an arbitrary value from the pre-regression patch + in practice I've never seen more than one */ + if (retry_count++ < 10) + goto retry; + return -EBUSY; + } + /* timeout */ if (args.v1.ucReplyStatus == 1) { DRM_DEBUG_KMS("dp_aux_ch timeout\n");