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Date:   Mon, 29 Jan 2018 16:31:32 -0500
From:   Sean Paul <seanpaul@chromium.org>
To:     Thierry Escande <thierry.escande@collabora.com>
Cc:     Archit Taneja <architt@codeaurora.org>,
        Inki Dae <inki.dae@samsung.com>,
        Thierry Reding <thierry.reding@gmail.com>,
        Sandy Huang <hjc@rock-chips.com>,
        Sean Paul <seanpaul@chromium.org>,
        David Airlie <airlied@linux.ie>,
        Tomasz Figa <tfiga@chromium.org>,
        Haixia Shi <hshi@chromium.org>,
        =?iso-8859-1?Q?=D8rjan?= Eide <orjan.eide@arm.com>,
        Zain Wang <wzz@rock-chips.com>,
        Yakir Yang <ykk@rock-chips.com>, Lin Huang <hl@rock-chips.com>,
        Douglas Anderson <dianders@chromium.org>,
        Mark Yao <mark.yao@rock-chips.com>,
        linux-kernel@vger.kernel.org, linux-rockchip@lists.infradead.org,
        dri-devel@lists.freedesktop.org
Subject: Re: [PATCH v2 22/43] drm/bridge: analogix_dp: Check dpcd write/read
 status
Message-ID: <20180129213132.wmkhg45bt24dnuog@art_vandelay>
References: <20180126131710.7622-1-thierry.escande@collabora.com>
 <20180126131710.7622-23-thierry.escande@collabora.com>
 <20180129211441.juzdm2qggw6igvqj@art_vandelay>
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On Mon, Jan 29, 2018 at 04:14:41PM -0500, Sean Paul wrote:
> On Fri, Jan 26, 2018 at 02:16:49PM +0100, Thierry Escande wrote:
> > From: Lin Huang <hl@rock-chips.com>
> > 
> > We need to check the dpcd write/read return value to see whether the
> > write/read was successful
> > 
> > Cc: Kristian H. Kristensen <hoegsberg@chromium.org>
> > Signed-off-by: Lin Huang <hl@rock-chips.com>
> > Signed-off-by: zain wang <wzz@rock-chips.com>
> > Signed-off-by: Douglas Anderson <dianders@chromium.org>
> > Signed-off-by: Sean Paul <seanpaul@chromium.org>
> > Signed-off-by: Thierry Escande <thierry.escande@collabora.com>
> > Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
> > ---
> >  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.
> 

Ah, this looks to be reversed in patch 27, hopefully we can rationalize things
a bit.

Sean

> >  		}
> >  		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

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