Revert "drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS"

This reverts commit 3c778a98bee16b4c7ba364a0101ee3c399a95b85 which is
commit a40c5d727b8111b5db424a1e43e14a1dcce1e77f upstream.

The upstream commit a40c5d727b8111b5db424a1e43e14a1dcce1e77f ("drm/dp:
Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS") the
reverted commit backported causes a regression, on one eDP panel at
least resulting in display flickering, described in detail at the Link:
below. The issue fixed by the upstream commit will need a different
solution, revert the backport for now.

Cc: intel-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Cc: Sasha Levin <sashal@kernel.org>
Link: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/14558
Signed-off-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c
index bb61bbdcce5b3cc8346882abce495cf58d627924..9fa13da513d24e183333be9985a75233c652cf4a 100644 (file)
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -664,7 +664,7 @@ ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset,
         * monitor doesn't power down exactly after the throw away read.
         */
        if (!aux->is_remote) {
-               ret = drm_dp_dpcd_probe(aux, DP_LANE0_1_STATUS);
+               ret = drm_dp_dpcd_probe(aux, DP_DPCD_REV);
                if (ret < 0)
                        return ret;
        }