linux-kernel - Re: [PATCH] drm: bridge: adv7511: use dev_err

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Message-ID: <Y02gmWSr07qONXih@pendragon.ideasonboard.com>
Date:   Mon, 17 Oct 2022 21:36:09 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Ahmad Fatoum <a.fatoum@...gutronix.de>
Cc:     Andrzej Hajda <andrzej.hajda@...el.com>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Robert Foss <robert.foss@...aro.org>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Archit Taneja <architt@...eaurora.org>, kernel@...gutronix.de,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm: bridge: adv7511: use dev_err_probe in probe function

Hi Ahmad,

Thank you for the patch.

On Mon, Oct 17, 2022 at 08:28:09PM +0200, Ahmad Fatoum wrote:
> adv7511 probe may need to be attempted multiple times before no
> -EPROBE_DEFER is returned. Currently, every such probe results in
> an error message:
> 
> [    4.534229] adv7511 1-003d: failed to find dsi host
> [    4.580288] adv7511 1-003d: failed to find dsi host
> 
> This is misleading, as there is no error and probe deferral is normal
> behavior. Fix this by using dev_err_probe that will suppress
> -EPROBE_DEFER errors. While at it, we touch all dev_err in the probe
> path. This makes the code more concise and included the error code
> everywhere to aid user in debugging.
> 
> Fixes: 1e4d58cd7f88 ("drm/bridge: adv7533: Create a MIPI DSI device")
> Signed-off-by: Ahmad Fatoum <a.fatoum@...gutronix.de>
> ---
>  drivers/gpu/drm/bridge/adv7511/adv7511_drv.c |  6 ++----
>  drivers/gpu/drm/bridge/adv7511/adv7533.c     | 18 ++++++------------
>  2 files changed, 8 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> index 1c37779b434a..4148b6d6f151 100644
> --- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> +++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> @@ -1229,10 +1229,8 @@ static int adv7511_probe(struct i2c_client *i2c, const struct i2c_device_id *id)
>  		return ret;
>  
>  	ret = adv7511_init_regulators(adv7511);
> -	if (ret) {
> -		dev_err(dev, "failed to init regulators\n");
> -		return ret;
> -	}
> +	if (ret)
> +		return dev_err_probe(dev, ret, "failed to init regulators\n");
>  
>  	/*
>  	 * The power down GPIO is optional. If present, toggle it from active to
> diff --git a/drivers/gpu/drm/bridge/adv7511/adv7533.c b/drivers/gpu/drm/bridge/adv7511/adv7533.c
> index ef6270806d1d..b32b796c25fb 100644
> --- a/drivers/gpu/drm/bridge/adv7511/adv7533.c
> +++ b/drivers/gpu/drm/bridge/adv7511/adv7533.c
> @@ -148,16 +148,12 @@ int adv7533_attach_dsi(struct adv7511 *adv)
>  						 };
>  
>  	host = of_find_mipi_dsi_host_by_node(adv->host_node);
> -	if (!host) {
> -		dev_err(dev, "failed to find dsi host\n");
> -		return -EPROBE_DEFER;
> -	}
> +	if (!host)
> +		return dev_err_probe(dev, -EPROBE_DEFER, "failed to find dsi host\n");

I'd wrap this line:

		return dev_err_probe(dev, -EPROBE_DEFER,
				     "failed to find dsi host\n");

>  
>  	dsi = devm_mipi_dsi_device_register_full(dev, host, &info);
> -	if (IS_ERR(dsi)) {
> -		dev_err(dev, "failed to create dsi device\n");
> -		return PTR_ERR(dsi);
> -	}
> +	if (IS_ERR(dsi))
> +		return dev_err_probe(dev, PTR_ERR(dsi), "failed to create dsi device\n");

Same here.

Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>

>  
>  	adv->dsi = dsi;
>  
> @@ -167,10 +163,8 @@ int adv7533_attach_dsi(struct adv7511 *adv)
>  			  MIPI_DSI_MODE_NO_EOT_PACKET | MIPI_DSI_MODE_VIDEO_HSE;
>  
>  	ret = devm_mipi_dsi_attach(dev, dsi);
> -	if (ret < 0) {
> -		dev_err(dev, "failed to attach dsi to host\n");
> -		return ret;
> -	}
> +	if (ret < 0)
> +		return dev_err_probe(dev, ret, "failed to attach dsi to host\n");
>  
>  	return 0;
>  }

-- 
Regards,

Laurent Pinchart