Re: [PATCH] drm/bridge: analogix_dp: detect Sink PSR state after configuring the PSR

[Sean Paul]

On Fri, Aug 26, 2016 at 6:19 AM, Yakir Yang <ykk@xxxxxxxxxxxxxx> wrote:
> Make sure the request PSR state could effect in analogix_dp_send_psr_spd()
> function, or printing the error Sink PSR state if we failed to effect
> the request PSR setting.
>
> Signed-off-by: Yakir Yang <ykk@xxxxxxxxxxxxxx>
> ---
>  drivers/gpu/drm/bridge/analogix/analogix_dp_core.c |  6 ++---
>  drivers/gpu/drm/bridge/analogix/analogix_dp_core.h |  4 ++--
>  drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c  | 26 ++++++++++++++++++++--
>  3 files changed, 28 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> index efac8ab..5a37de8 100644
> --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> @@ -115,8 +115,7 @@ int analogix_dp_enable_psr(struct device *dev)
>         psr_vsc.DB0 = 0;
>         psr_vsc.DB1 = EDP_VSC_PSR_STATE_ACTIVE | EDP_VSC_PSR_CRC_VALUES_VALID;
>
> -       analogix_dp_send_psr_spd(dp, &psr_vsc);
> -       return 0;
> +       return analogix_dp_send_psr_spd(dp, &psr_vsc);
>  }
>  EXPORT_SYMBOL_GPL(analogix_dp_enable_psr);
>
> @@ -138,8 +137,7 @@ int analogix_dp_disable_psr(struct device *dev)
>         psr_vsc.DB0 = 0;
>         psr_vsc.DB1 = 0;
>
> -       analogix_dp_send_psr_spd(dp, &psr_vsc);
> -       return 0;
> +       return analogix_dp_send_psr_spd(dp, &psr_vsc);
>  }
>  EXPORT_SYMBOL_GPL(analogix_dp_disable_psr);
>
> diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.h b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.h
> index 473b980..f617a9d 100644
> --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.h
> +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.h
> @@ -283,7 +283,7 @@ void analogix_dp_config_video_slave_mode(struct analogix_dp_device *dp);
>  void analogix_dp_enable_scrambling(struct analogix_dp_device *dp);
>  void analogix_dp_disable_scrambling(struct analogix_dp_device *dp);
>  void analogix_dp_enable_psr_crc(struct analogix_dp_device *dp);
> -void analogix_dp_send_psr_spd(struct analogix_dp_device *dp,
> -                             struct edp_vsc_psr *vsc);
> +int analogix_dp_send_psr_spd(struct analogix_dp_device *dp,
> +                            struct edp_vsc_psr *vsc);
>
>  #endif /* _ANALOGIX_DP_CORE_H */
> diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
> index 52c1b6b..505e9d8 100644
> --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
> +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
> @@ -1328,9 +1328,11 @@ void analogix_dp_enable_psr_crc(struct analogix_dp_device *dp)
>         writel(PSR_VID_CRC_ENABLE, dp->reg_base + ANALOGIX_DP_CRC_CON);
>  }
>
> -void analogix_dp_send_psr_spd(struct analogix_dp_device *dp,
> -                             struct edp_vsc_psr *vsc)
> +int analogix_dp_send_psr_spd(struct analogix_dp_device *dp,
> +                            struct edp_vsc_psr *vsc)
>  {
> +       unsigned long timeout;
> +       unsigned char sink;

u8

>         unsigned int val;
>
>         /* don't send info frame */
> @@ -1372,4 +1374,24 @@ void analogix_dp_send_psr_spd(struct analogix_dp_device *dp,
>         val = readl(dp->reg_base + ANALOGIX_DP_PKT_SEND_CTL);
>         val |= IF_EN;
>         writel(val, dp->reg_base + ANALOGIX_DP_PKT_SEND_CTL);
> +
> +       timeout = jiffies + msecs_to_jiffies(100);

Pull 100 out into a #define

> +       while (1) {
> +               analogix_dp_read_byte_from_dpcd(dp, DP_PSR_STATUS, &sink);

You should be checking return value here.

> +
> +               if (vsc->DB1 && sink == DP_PSR_SINK_ACTIVE_RFB)
> +                       break;
> +
> +               if (!vsc->DB1 && sink == DP_PSR_SINK_INACTIVE)
> +                       break;
> +
> +               if (time_after(jiffies, timeout)) {
> +                       dev_warn(dp->dev, "Failed to effect PSR: %x", sink);
> +                       return -EBUSY;

-ETIMEDOUT is more appropriate

> +               }
> +
> +               usleep_range(1000, 1500);
> +       }

The while(1) loop is a little scary. I'd rather do:

while (time_before(jiffies, timeout)) {
               ret = analogix_dp_read_byte_from_dpcd(dp, DP_PSR_STATUS, &sink);
               if (ret != 1) {
                       DRM_DEV_ERROR(dp->dev, "PSR_STATUS read failed
ret=%d", ret);
                       return ret;
               }

               if (vsc->DB1 && sink == DP_PSR_SINK_ACTIVE_RFB ||
                   !vsc->DB1 && sink == DP_PSR_SINK_INACTIVE)
                       return 0;

               usleep_range(1000, 1500);
}

dev_warn(dp->dev, "Failed to effect PSR: %x", sink);
return -ETIMEDOUT;



> +
> +       return 0;
>  }
> --
> 1.9.1
>
>
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