Re: [PATCH v2 22/43] drm/bridge: analogix_dp: Check dpcd write/read status

[Sean Paul]

On Fri, Jan 26, 2018 at 02:16:49PM +0100, Thierry Escande wrote:
> From: Lin Huang <hl@xxxxxxxxxxxxxx>
> 
> We need to check the dpcd write/read return value to see whether the
> write/read was successful
> 
> Cc: Kristian H. Kristensen <hoegsberg@xxxxxxxxxxxx>
> Signed-off-by: Lin Huang <hl@xxxxxxxxxxxxxx>
> Signed-off-by: zain wang <wzz@xxxxxxxxxxxxxx>
> Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
> Signed-off-by: Sean Paul <seanpaul@xxxxxxxxxxxx>
> Signed-off-by: Thierry Escande <thierry.escande@xxxxxxxxxxxxx>
> Reviewed-by: Andrzej Hajda <a.hajda@xxxxxxxxxxx>
> ---
>  drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 181 +++++++++++++++------
>  1 file changed, 132 insertions(+), 49 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> index 846574d0dcb0..501f7b4a23d6 100644
> --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> @@ -160,80 +160,135 @@ int analogix_dp_disable_psr(struct analogix_dp_device *dp)
>  }
>  EXPORT_SYMBOL_GPL(analogix_dp_disable_psr);
>  
> -static bool analogix_dp_detect_sink_psr(struct analogix_dp_device *dp)
> +static int analogix_dp_detect_sink_psr(struct analogix_dp_device *dp)
>  {
>  	unsigned char psr_version;
> +	int ret;
> +
> +	ret = drm_dp_dpcd_readb(&dp->aux, DP_PSR_SUPPORT, &psr_version);
> +	if (ret != 1) {
> +		dev_err(dp->dev, "failed to get PSR version, disable it\n");
> +		return ret;
> +	}
>  
> -	drm_dp_dpcd_readb(&dp->aux, DP_PSR_SUPPORT, &psr_version);
>  	dev_dbg(dp->dev, "Panel PSR version : %x\n", psr_version);
>  
> -	return (psr_version & DP_PSR_IS_SUPPORTED) ? true : false;
> +	dp->psr_enable = (psr_version & DP_PSR_IS_SUPPORTED) ? true : false;
> +
> +	return 0;
>  }
>  
> -static void analogix_dp_enable_sink_psr(struct analogix_dp_device *dp)
> +static int analogix_dp_enable_sink_psr(struct analogix_dp_device *dp)
>  {
>  	unsigned char psr_en;
> +	int ret;
>  
>  	/* Disable psr function */
> -	drm_dp_dpcd_readb(&dp->aux, DP_PSR_EN_CFG, &psr_en);
> +	ret = drm_dp_dpcd_readb(&dp->aux, DP_PSR_EN_CFG, &psr_en);
> +	if (ret != 1) {
> +		dev_err(dp->dev, "failed to get psr config\n");
> +		goto end;
> +	}
> +
>  	psr_en &= ~DP_PSR_ENABLE;
> -	drm_dp_dpcd_writeb(&dp->aux, DP_PSR_EN_CFG, psr_en);
> +	ret = drm_dp_dpcd_writeb(&dp->aux, DP_PSR_EN_CFG, psr_en);
> +	if (ret != 1) {
> +		dev_err(dp->dev, "failed to disable panel psr\n");
> +		goto end;
> +	}
>  
>  	/* Main-Link transmitter remains active during PSR active states */
>  	psr_en = DP_PSR_MAIN_LINK_ACTIVE | DP_PSR_CRC_VERIFICATION;
> -	drm_dp_dpcd_writeb(&dp->aux, DP_PSR_EN_CFG, psr_en);
> +	ret = drm_dp_dpcd_writeb(&dp->aux, DP_PSR_EN_CFG, psr_en);
> +	if (ret != 1) {
> +		dev_err(dp->dev, "failed to set panel psr\n");
> +		goto end;
> +	}
>  
>  	/* Enable psr function */
>  	psr_en = DP_PSR_ENABLE | DP_PSR_MAIN_LINK_ACTIVE |
>  		 DP_PSR_CRC_VERIFICATION;
> -	drm_dp_dpcd_writeb(&dp->aux, DP_PSR_EN_CFG, psr_en);
> +	ret = drm_dp_dpcd_writeb(&dp->aux, DP_PSR_EN_CFG, psr_en);
> +	if (ret != 1) {
> +		dev_err(dp->dev, "failed to set panel psr\n");
> +		goto end;
> +	}
>  
>  	analogix_dp_enable_psr_crc(dp);
> +
> +	return 0;
> +end:
> +	dev_err(dp->dev, "enable psr fail, force to disable psr\n");
> +	dp->psr_enable = false;
> +
> +	return ret;
>  }
>  
> -static void
> +static int
>  analogix_dp_enable_rx_to_enhanced_mode(struct analogix_dp_device *dp,
>  				       bool enable)
>  {
>  	u8 data;
> +	int ret;
>  
> -	drm_dp_dpcd_readb(&dp->aux, DP_LANE_COUNT_SET, &data);
> +	ret = drm_dp_dpcd_readb(&dp->aux, DP_LANE_COUNT_SET, &data);
> +	if (ret < 0)
> +		return ret;
>  
>  	if (enable)
> -		drm_dp_dpcd_writeb(&dp->aux, DP_LANE_COUNT_SET,
> -				   DP_LANE_COUNT_ENHANCED_FRAME_EN |
> -					DPCD_LANE_COUNT_SET(data));
> +		ret = drm_dp_dpcd_writeb(&dp->aux, DP_LANE_COUNT_SET,
> +					 DP_LANE_COUNT_ENHANCED_FRAME_EN |
> +					 DPCD_LANE_COUNT_SET(data));
>  	else
> -		drm_dp_dpcd_writeb(&dp->aux, DP_LANE_COUNT_SET,
> -				   DPCD_LANE_COUNT_SET(data));
> +		ret = drm_dp_dpcd_writeb(&dp->aux, DP_LANE_COUNT_SET,
> +					 DPCD_LANE_COUNT_SET(data));
> +
> +	return ret < 0 ? ret : 0;
>  }
>  
> -static int analogix_dp_is_enhanced_mode_available(struct analogix_dp_device *dp)
> +static int analogix_dp_is_enhanced_mode_available(struct analogix_dp_device *dp,
> +						  u8 *enhanced_mode_support)
>  {
>  	u8 data;
> -	int retval;
> +	int ret;
>  
> -	drm_dp_dpcd_readb(&dp->aux, DP_MAX_LANE_COUNT, &data);
> -	retval = DPCD_ENHANCED_FRAME_CAP(data);
> +	ret = drm_dp_dpcd_readb(&dp->aux, DP_MAX_LANE_COUNT, &data);
> +	if (ret < 0)

Above we check for ret != 1, so we should probably stay consistent. Same nit
throughout the patch.

> +		return ret;
>  
> -	return retval;
> +	*enhanced_mode_support = DPCD_ENHANCED_FRAME_CAP(data);
> +
> +	return 0;
>  }
>  
> -static void analogix_dp_set_enhanced_mode(struct analogix_dp_device *dp)
> +static int analogix_dp_set_enhanced_mode(struct analogix_dp_device *dp)
>  {
>  	u8 data;
> +	int ret;
> +
> +	ret = analogix_dp_is_enhanced_mode_available(dp, &data);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = analogix_dp_enable_rx_to_enhanced_mode(dp, data);
> +	if (ret < 0)
> +		return ret;
>  
> -	data = analogix_dp_is_enhanced_mode_available(dp);
> -	analogix_dp_enable_rx_to_enhanced_mode(dp, data);
>  	analogix_dp_enable_enhanced_mode(dp, data);
> +
> +	return 0;
>  }
>  
> -static void analogix_dp_training_pattern_dis(struct analogix_dp_device *dp)
> +static int analogix_dp_training_pattern_dis(struct analogix_dp_device *dp)
>  {
> +	int retval;

Above we're replacing retval with ret, however here we introduce retval.

> +
>  	analogix_dp_set_training_pattern(dp, DP_NONE);
>  
> -	drm_dp_dpcd_writeb(&dp->aux, DP_TRAINING_PATTERN_SET,
> -			   DP_TRAINING_PATTERN_DISABLE);
> +	retval = drm_dp_dpcd_writeb(&dp->aux, DP_TRAINING_PATTERN_SET,
> +				    DP_TRAINING_PATTERN_DISABLE);
> +
> +	return retval < 0 ? retval : 0;
>  }
>  
>  static void
> @@ -282,7 +337,11 @@ static int analogix_dp_link_start(struct analogix_dp_device *dp)
>  	if (retval < 0)
>  		return retval;
>  	/* set enhanced mode if available */
> -	analogix_dp_set_enhanced_mode(dp);
> +	retval = analogix_dp_set_enhanced_mode(dp);
> +	if (retval < 0) {
> +		dev_err(dp->dev, "failed to set enhance mode\n");
> +		return retval;
> +	}
>  
>  	/* Set TX pre-emphasis to minimum */
>  	for (lane = 0; lane < lane_count; lane++)
> @@ -567,10 +626,11 @@ static int analogix_dp_process_equalizer_training(struct analogix_dp_device *dp)
>  
>  	if (!analogix_dp_channel_eq_ok(link_status, link_align, lane_count)) {
>  		/* traing pattern Set to Normal */
> -		analogix_dp_training_pattern_dis(dp);
> +		retval = analogix_dp_training_pattern_dis(dp);
> +		if (retval < 0)
> +			return retval;
>  
>  		dev_info(dp->dev, "Link Training success!\n");
> -
>  		analogix_dp_get_link_bandwidth(dp, &reg);
>  		dp->link_train.link_rate = reg;
>  		dev_dbg(dp->dev, "final bandwidth = %.2x\n",
> @@ -807,7 +867,6 @@ static int analogix_dp_train_link(struct analogix_dp_device *dp)
>  
>  static int analogix_dp_config_video(struct analogix_dp_device *dp)
>  {
> -	int retval = 0;
>  	int timeout_loop = 0;
>  	int done_count = 0;
>  
> @@ -825,8 +884,9 @@ static int analogix_dp_config_video(struct analogix_dp_device *dp)
>  		if (analogix_dp_is_slave_video_stream_clock_on(dp) == 0)
>  			break;
>  		if (timeout_loop > DP_TIMEOUT_LOOP_COUNT) {
> -			dev_err(dp->dev, "Timeout of slave video streamclk ok\n");
> -			return -ETIMEDOUT;
> +			dev_warn(dp->dev,
> +				 "Ignoring timeout of slave video streamclk ok\n");
> +			break;

This change has sort of snuck in here. It doesn't seem related to the change,
but maybe I'm overlooking something.

>  		}
>  		usleep_range(1000, 1001);

Unrelated: This is pretty hilarious.

>  	}
> @@ -865,30 +925,38 @@ static int analogix_dp_config_video(struct analogix_dp_device *dp)
>  		usleep_range(1000, 1001);
>  	}
>  
> -	if (retval != 0)
> -		dev_err(dp->dev, "Video stream is not detected!\n");
> -
> -	return retval;
> +	return 0;
>  }
>  
> -static void analogix_dp_enable_scramble(struct analogix_dp_device *dp,
> -					bool enable)
> +static int analogix_dp_enable_scramble(struct analogix_dp_device *dp,
> +				       bool enable)
>  {
>  	u8 data;
> +	int ret;
>  
>  	if (enable) {
>  		analogix_dp_enable_scrambling(dp);
>  
> -		drm_dp_dpcd_readb(&dp->aux, DP_TRAINING_PATTERN_SET, &data);
> -		drm_dp_dpcd_writeb(&dp->aux, DP_TRAINING_PATTERN_SET,
> +		ret = drm_dp_dpcd_readb(&dp->aux, DP_TRAINING_PATTERN_SET,
> +					&data);
> +		if (ret != 1)
> +			return ret;
> +
> +		ret = drm_dp_dpcd_writeb(&dp->aux, DP_TRAINING_PATTERN_SET,
>  				   (u8)(data & ~DP_LINK_SCRAMBLING_DISABLE));
>  	} else {
>  		analogix_dp_disable_scrambling(dp);
>  
> -		drm_dp_dpcd_readb(&dp->aux, DP_TRAINING_PATTERN_SET, &data);
> -		drm_dp_dpcd_writeb(&dp->aux, DP_TRAINING_PATTERN_SET,
> +		ret = drm_dp_dpcd_readb(&dp->aux, DP_TRAINING_PATTERN_SET,
> +					&data);
> +		if (ret != 1)
> +			return ret;
> +
> +		ret = drm_dp_dpcd_writeb(&dp->aux, DP_TRAINING_PATTERN_SET,
>  				   (u8)(data | DP_LINK_SCRAMBLING_DISABLE));

This should probably be explicitly checked as well, since the inline conditional
in the return isn't checking what the rest of the function is.

>  	}
> +
> +	return ret < 0 ? ret : 0;
>  }
>  
>  static irqreturn_t analogix_dp_hardirq(int irq, void *arg)
> @@ -943,23 +1011,36 @@ static int analogix_dp_commit(struct analogix_dp_device *dp)
>  		return ret;
>  	}
>  
> -	analogix_dp_enable_scramble(dp, 1);
> +	ret = analogix_dp_enable_scramble(dp, 1);
> +	if (ret < 0) {
> +		dev_err(dp->dev, "can not enable scramble\n");
> +		return ret;
> +	}
>  
>  	analogix_dp_init_video(dp);
>  	ret = analogix_dp_config_video(dp);
> -	if (ret)
> +	if (ret) {
>  		dev_err(dp->dev, "unable to config video\n");
> +		return ret;
> +	}
>  
>  	/* Safe to enable the panel now */
>  	if (dp->plat_data->panel) {
> -		if (drm_panel_enable(dp->plat_data->panel))
> +		ret = drm_panel_enable(dp->plat_data->panel);
> +		if (ret) {
>  			DRM_ERROR("failed to enable the panel\n");
> +			return ret;
> +		}
>  	}
>  
> -	dp->psr_enable = analogix_dp_detect_sink_psr(dp);
> +	ret = analogix_dp_detect_sink_psr(dp);
> +	if (ret)
> +		return ret;
> +
>  	if (dp->psr_enable)
> -		analogix_dp_enable_sink_psr(dp);
> -	return 0;
> +		ret = analogix_dp_enable_sink_psr(dp);
> +
> +	return ret;
>  }
>  
>  /*
> @@ -1186,8 +1267,10 @@ static int analogix_dp_set_bridge(struct analogix_dp_device *dp)
>  	}
>  
>  	ret = analogix_dp_commit(dp);
> -	if (ret)
> +	if (ret) {
> +		DRM_ERROR("dp commit error, ret = %d\n", ret);
>  		goto out_dp_init;
> +	}
>  
>  	enable_irq(dp->irq);
>  	return 0;
> -- 
> 2.14.1
> 

-- 
Sean Paul, Software Engineer, Google / Chromium OS