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Subject: Re: [PATCH v5 16/36] drm/bridge: analogix_dp: Check dpcd write/read
 status
To:     Enric Balletbo i Serra <enric.balletbo@collabora.com>,
        inki.dae@samsung.com, thierry.reding@gmail.com, hjc@rock-chips.com,
        seanpaul@chromium.org, airlied@linux.ie, tfiga@chromium.org,
        heiko@sntech.de
Cc:     dri-devel@lists.freedesktop.org, dianders@chromium.org,
        a.hajda@samsung.com, ykk@rock-chips.com, kernel@collabora.com,
        m.szyprowski@samsung.com, linux-samsung-soc@vger.kernel.org,
        jy0922.shim@samsung.com, rydberg@bitmath.org, krzk@kernel.org,
        linux-rockchip@lists.infradead.org, kgene@kernel.org,
        linux-input@vger.kernel.org, orjan.eide@arm.com,
        wxt@rock-chips.com, jeffy.chen@rock-chips.com,
        linux-arm-kernel@lists.infradead.org, mark.yao@rock-chips.com,
        wzz@rock-chips.com, hl@rock-chips.com, jingoohan1@gmail.com,
        sw0312.kim@samsung.com, linux-kernel@vger.kernel.org,
        kyungmin.park@samsung.com, Laurent.pinchart@ideasonboard.com,
        kuankuan.y@gmail.com, hshi@chromium.org,
        "Kristian H . Kristensen" <hoegsberg@chromium.org>
References: <20180309222327.18689-1-enric.balletbo@collabora.com>
 <20180309222327.18689-17-enric.balletbo@collabora.com>
From:   Archit Taneja <architt@codeaurora.org>
Message-ID: <216ddbe8-c044-e6e8-115a-69b5c2985a8e@codeaurora.org>
Date:   Wed, 14 Mar 2018 11:49:17 +0530
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On Saturday 10 March 2018 03:53 AM, Enric Balletbo i Serra 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
> 

Reviewed-by: Archit Taneja <architt@codeaurora.org>

Thanks,
Archit

> 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>
> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
> Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
> ---
> 
>   drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 169 ++++++++++++++++-----
>   1 file changed, 127 insertions(+), 42 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> index 1eed35f9eb8d..be6eddd0d0a7 100644
> --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> @@ -160,80 +160,137 @@ 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 != 1)
> +		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 != 1) {
> +		*enhanced_mode_support = 0;
> +		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 ret;
> +
>   	analogix_dp_set_training_pattern(dp, DP_NONE);
>   
> -	drm_dp_dpcd_writeb(&dp->aux, DP_TRAINING_PATTERN_SET,
> -			   DP_TRAINING_PATTERN_DISABLE);
> +	ret = drm_dp_dpcd_writeb(&dp->aux, DP_TRAINING_PATTERN_SET,
> +				 DP_TRAINING_PATTERN_DISABLE);
> +
> +	return ret < 0 ? ret : 0;
>   }
>   
>   static void
> @@ -282,7 +339,11 @@ 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 +628,11 @@ 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",
> @@ -867,24 +929,32 @@ static int analogix_dp_config_video(struct analogix_dp_device *dp)
>   	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));
>   	}
> +	return ret < 0 ? ret : 0;
>   }
>   
>   static irqreturn_t analogix_dp_hardirq(int irq, void *arg)
> @@ -939,23 +1009,36 @@ 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;
>   }
>   
>   /*
> @@ -1185,8 +1268,10 @@ 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;
>