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| author | Kuogee Hsieh <quic_khsieh@quicinc.com> | 2022-09-12 19:23:48 +0300 |
|---|---|---|
| committer | Abhinav Kumar <quic_abhinavk@quicinc.com> | 2022-09-30 19:57:53 +0300 |
| commit | 70445dee1b4cf44c9fecc580dfa08079011866f1 (patch) | |
| tree | fe956b8afea7bd3ef82064a038ef8d76364740f8 /drivers/gpu/drm/msm/dp | |
| parent | 152d394842bb564148e68b92486a87db0bf54859 (diff) | |
| download | linux-70445dee1b4cf44c9fecc580dfa08079011866f1.tar.xz | |
drm/msm/dp: cleared DP_DOWNSPREAD_CTRL register before start link training
DOWNSPREAD_CTRL (0x107) shall be cleared to 0 upon power-on reset or an
upstream device disconnect. This patch will enforce this rule by always
cleared DOWNSPREAD_CTRL register to 0 before start link training. At rare
case that DP MSA timing parameters may be mis-interpreted by the sink
which causes audio sampling rate be calculated wrongly and cause audio
did not work at sink if DOWNSPREAD_CTRL register is not cleared to 0.
Changes in v2:
1) fix spelling at commit text
2) merge ssc variable into encoding[0]
Changes in v3:
-- correct spelling of DOWNSPREAD_CTRL
-- replace err with len of ssize_t
Changes in v4:
-- split into 2 patches
Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Fixes: c943b4948b58 ("drm/msm/dp: add displayPort driver support")
Patchwork: https://patchwork.freedesktop.org/patch/502532/
Link: https://lore.kernel.org/r/1662999830-13916-2-git-send-email-quic_khsieh@quicinc.com
Signed-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Diffstat (limited to 'drivers/gpu/drm/msm/dp')
| -rw-r--r-- | drivers/gpu/drm/msm/dp/dp_ctrl.c | 13 |
1 files changed, 5 insertions, 8 deletions
diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c index 3854c9f1f7e9..dd26ca651a05 100644 --- a/drivers/gpu/drm/msm/dp/dp_ctrl.c +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c @@ -1243,8 +1243,7 @@ static int dp_ctrl_link_train(struct dp_ctrl_private *ctrl, { int ret = 0; const u8 *dpcd = ctrl->panel->dpcd; - u8 encoding = DP_SET_ANSI_8B10B; - u8 ssc; + u8 encoding[] = { 0, DP_SET_ANSI_8B10B }; u8 assr; struct dp_link_info link_info = {0}; @@ -1256,13 +1255,11 @@ static int dp_ctrl_link_train(struct dp_ctrl_private *ctrl, dp_aux_link_configure(ctrl->aux, &link_info); - if (drm_dp_max_downspread(dpcd)) { - ssc = DP_SPREAD_AMP_0_5; - drm_dp_dpcd_write(ctrl->aux, DP_DOWNSPREAD_CTRL, &ssc, 1); - } + if (drm_dp_max_downspread(dpcd)) + encoding[0] |= DP_SPREAD_AMP_0_5; - drm_dp_dpcd_write(ctrl->aux, DP_MAIN_LINK_CHANNEL_CODING_SET, - &encoding, 1); + /* config DOWNSPREAD_CTRL and MAIN_LINK_CHANNEL_CODING_SET */ + drm_dp_dpcd_write(ctrl->aux, DP_DOWNSPREAD_CTRL, encoding, 2); if (drm_dp_alternate_scrambler_reset_cap(dpcd)) { assr = DP_ALTERNATE_SCRAMBLER_RESET_ENABLE; |