drm/amd/display: fix resume hang because of DP short pulse
authorArindam Nath <arindam.nath@amd.com>
Wed, 26 Apr 2017 12:09:56 +0000 (17:39 +0530)
committerAlex Deucher <alexander.deucher@amd.com>
Tue, 26 Sep 2017 22:06:47 +0000 (18:06 -0400)
commit03ea364c8e156b2bb5c64465718e8ebd75e3df22
treef8afa2831da260206e3f5efef62bae36944cb40a
parentba624cddbc002816e376d588290a48f77ff4b06f
drm/amd/display: fix resume hang because of DP short pulse

There is a hard hang observed during resume from S3 when
the system receives a DP short pulse interrupt. This is
because there are two code paths contending for GPIO
access for AUX channel transactions. One such path is
through amdgpu_dm_display_resume() function which is
invoked from the regular system resume code path. The
other path is through handle_hpd_rx_irq(), which is
invoked in response to system receiving DP short pulse
interrupt. handle_hpd_rx_irq() guards against conflicting
GPIO access using hpd_lock, but the GPIO access from
amdgpu_dm_display_resume() remains unguarded.

This patch makes sure we use hpd_lock inside
amdgpu_dm_display_resume() to avoid race conditions
for GPIO access.

Signed-off-by: Arindam Nath <arindam.nath@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c