[PATCH 5.10.y] Revert "drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS"

[Imre Deak]

This reverts commit 89d17a2d89a83c5b7643ca934651a3f9229e4734.

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-...@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Cc: Sasha Levin <sas...@kernel.org>
Link: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/14558
Signed-off-by: Imre Deak <imre.d...@intel.com>
---
 drivers/gpu/drm/drm_dp_helper.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index ba8ab1dc4912..6ba16db77500 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -299,7 +299,7 @@ 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_access(aux, DP_AUX_NATIVE_READ, 
DP_LANE0_1_STATUS,
+               ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, DP_DPCD_REV,
                                         buffer, 1);
                if (ret != 1)
                        goto out;
-- 
2.49.1