drm/msm/dp: retry 3 times if set sink to D0 poweer state failed

Bring sink out of D3 (power down) mode into D0 (normal operation) mode
by setting DP_SET_POWER_D0 bit to DP_SET_POWER dpcd register. This
patch will retry 3 times if written to DP_SET_POWER register failed.

Changes in v5:
-- split into two patches

Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/502536/
Link: https://lore.kernel.org/r/1662999830-13916-4-git-send-email-quic_khsieh@quicinc.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

diff --git a/drivers/gpu/drm/msm/dp/dp_link.c b/drivers/gpu/drm/msm/dp/dp_link.c
index ef35fac..f1f1d64 100644 (file)
--- a/drivers/gpu/drm/msm/dp/dp_link.c
+++ b/drivers/gpu/drm/msm/dp/dp_link.c
@@ -50,6 +50,7 @@ static int dp_aux_link_power_up(struct drm_dp_aux *aux,
 {
        u8 value;
        ssize_t len;
+       int i;
 
        if (link->revision < 0x11)
                return 0;
@@ -61,11 +62,13 @@ static int dp_aux_link_power_up(struct drm_dp_aux *aux,
        value &= ~DP_SET_POWER_MASK;
        value |= DP_SET_POWER_D0;
 
-       len = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value);
-       if (len < 0)
-               return len;
-
-       usleep_range(1000, 2000);
+       /* retry for 1ms to give the sink time to wake up */
+       for (i = 0; i < 3; i++) {
+               len = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value);
+               usleep_range(1000, 2000);
+               if (len == 1)
+                       break;
+       }
 
        return 0;
 }