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 <[email protected]> --- drivers/gpu/drm/msm/dp/dp_link.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/msm/dp/dp_link.c b/drivers/gpu/drm/msm/dp/dp_link.c index 9d5381d..4360728 100644 --- 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; } -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project
