Messages in this thread | | | Date | Wed, 2 Nov 2022 18:51:41 +0300 | Subject | Re: [PATCH v5 3/3] drm/msm/dp: retry 3 times if set sink to D0 poweer state failed | From | Dmitry Baryshkov <> |
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On 12/09/2022 22:26, Kuogee Hsieh wrote: > > On 9/12/2022 11:37 AM, Dmitry Baryshkov wrote: >> On 12/09/2022 19:23, Kuogee Hsieh wrote: >>> 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. >> >> Could you please elaborate this change? Can the sink succeed in >> reading the DP_SET_POWER, but fail writing DP_SET_POWER? > > yes, there is possible since it is not only set local sink device but > also all downstream sink devices to D0 state.
Ack. Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> >> >>> >>> Changes in v5: >>> -- split into two patches >>> >>> Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com> >>> --- >>> 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; >>> } >>
-- With best wishes Dmitry
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