Re: [PATCH v4 2/2] drm/msm/dp: retry 3 times if set sink to D0 poweer state failed

[Dmitry Baryshkov]

On Fri, 9 Sept 2022 at 00:18, 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.
>
> Changes in v4:
> -- split into two patches
>
> Signed-off-by: Kuogee Hsieh 
> ---
>  drivers/gpu/drm/msm/dp/dp_link.c | 21 -
>  1 file changed, 12 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/dp/dp_link.c 
> b/drivers/gpu/drm/msm/dp/dp_link.c
> index 36f0af0..7b5ecf5 100644
> --- a/drivers/gpu/drm/msm/dp/dp_link.c
> +++ b/drivers/gpu/drm/msm/dp/dp_link.c
> @@ -49,23 +49,26 @@ static int dp_aux_link_power_up(struct drm_dp_aux *aux,
> struct dp_link_info *link)
>  {
> u8 value;
> -   int err;
> +   ssize_t len;
> +   int i;
>
> if (link->revision < 0x11)
> return 0;
>
> -   err = drm_dp_dpcd_readb(aux, DP_SET_POWER, );
> -   if (err < 0)
> -   return err;
> +   len = drm_dp_dpcd_readb(aux, DP_SET_POWER, );
> +   if (len < 0)
> +   return len;

This is a separate patch.

>
> value &= ~DP_SET_POWER_MASK;
> value |= DP_SET_POWER_D0;
>
> -   err = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value);
> -   if (err < 0)
> -   return err;
> -
> -   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
>


-- 
With best wishes
Dmitry

[PATCH v4 2/2] drm/msm/dp: retry 3 times if set sink to D0 poweer state failed

[Kuogee Hsieh]

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 v4:
-- split into two patches

Signed-off-by: Kuogee Hsieh 
---
 drivers/gpu/drm/msm/dp/dp_link.c | 21 -
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_link.c b/drivers/gpu/drm/msm/dp/dp_link.c
index 36f0af0..7b5ecf5 100644
--- a/drivers/gpu/drm/msm/dp/dp_link.c
+++ b/drivers/gpu/drm/msm/dp/dp_link.c
@@ -49,23 +49,26 @@ static int dp_aux_link_power_up(struct drm_dp_aux *aux,
struct dp_link_info *link)
 {
u8 value;
-   int err;
+   ssize_t len;
+   int i;
 
if (link->revision < 0x11)
return 0;
 
-   err = drm_dp_dpcd_readb(aux, DP_SET_POWER, );
-   if (err < 0)
-   return err;
+   len = drm_dp_dpcd_readb(aux, DP_SET_POWER, );
+   if (len < 0)
+   return len;
 
value &= ~DP_SET_POWER_MASK;
value |= DP_SET_POWER_D0;
 
-   err = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value);
-   if (err < 0)
-   return err;
-
-   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