提交 1a738347 编写于 作者: A Arindam Nath 提交者: Alex Deucher

drm/radeon: fix DP link training issue with second 4K monitor

There is an issue observed when we hotplug a second DP
4K monitor to the system. Sometimes, the link training
fails for the second monitor after HPD interrupt
generation.

The issue happens when some queued or deferred transactions
are already present on the AUX channel when we initiate
a new transcation to (say) get DPCD or during link training.

We set AUX_IGNORE_HPD_DISCON bit in the AUX_CONTROL
register so that we can ignore any such deferred
transactions when a new AUX transaction is initiated.
Signed-off-by: NArindam Nath <arindam.nath@amd.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
上级 fca09716
......@@ -105,7 +105,7 @@ radeon_dp_aux_transfer_native(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg
tmp &= AUX_HPD_SEL(0x7);
tmp |= AUX_HPD_SEL(chan->rec.hpd);
tmp |= AUX_EN | AUX_LS_READ_EN;
tmp |= AUX_EN | AUX_LS_READ_EN | AUX_HPD_DISCON(0x1);
WREG32(AUX_CONTROL + aux_offset[instance], tmp);
......
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