linux-kernel - Re: [RFC PATCH v4 8/8] drm/rockchip: Add device links for master and components

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Date:   Tue, 17 Oct 2017 14:24:42 -0400
From:   Sean Paul <seanpaul@...omium.org>
To:     Jeffy Chen <jeffy.chen@...k-chips.com>
Cc:     linux-kernel@...r.kernel.org, dmitry.torokhov@...il.com,
        heiko@...ech.de, briannorris@...omium.org, rjw@...ysocki.net,
        dianders@...omium.org, tfiga@...omium.org, broonie@...nel.org,
        seanpaul@...omium.org, Mark Yao <mark.yao@...k-chips.com>,
        dri-devel@...ts.freedesktop.org,
        linux-rockchip@...ts.infradead.org,
        David Airlie <airlied@...ux.ie>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [RFC PATCH v4 8/8] drm/rockchip: Add device links for master and
 components

On Tue, Oct 17, 2017 at 06:16:24PM +0800, Jeffy Chen wrote:
> Since we are trying to access components' resources in the master's
> suspend/resume PM callbacks(e.g. panel), add device links to correct
> the suspend/resume and shutdown ordering.
> 
> Signed-off-by: Jeffy Chen <jeffy.chen@...k-chips.com>
> ---
> 
> Changes in v4: None
> Changes in v3: None
> Changes in v2:
> Use device link to correct the suspend/resume and shutdown ordering,
> instead of converting rockchip spi's suspend/resume PM callbacks to
> late suspend/resume PM callbacks.
> 
>  drivers/gpu/drm/rockchip/rockchip_drm_drv.c | 24 +++++++++++++++++++++---
>  1 file changed, 21 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
> index 76d63de5921d..af18967f699b 100644
> --- a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
> @@ -337,6 +337,8 @@ static struct component_match *rockchip_drm_match_add(struct device *dev)
>  
>  			if (!d)
>  				break;
> +
> +			device_link_add(dev, d, DL_FLAG_STATELESS);
>  			component_match_add(dev, &match, compare_dev, d);
>  		} while (true);
>  	}
> @@ -406,6 +408,7 @@ static int rockchip_drm_platform_of_probe(struct device *dev)
>  static int rockchip_drm_platform_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
> +	struct device_link *link;
>  	struct component_match *match = NULL;
>  	int ret;
>  
> @@ -414,16 +417,31 @@ static int rockchip_drm_platform_probe(struct platform_device *pdev)
>  		return ret;
>  
>  	match = rockchip_drm_match_add(dev);
> -	if (IS_ERR(match))
> -		return PTR_ERR(match);
> +	if (IS_ERR(match)) {
> +		ret = PTR_ERR(match);
> +		goto err_cleanup_dev_links;

This cleanup should take place in rockchip_drm_match_add(). The review theme for
this entire series is that, when possible, we should cleanup things where they
are initialized.

Since you'll also need to clean up the links elsewhere, consider adding a helper
function to do the cleanup (rockchip_drm_match_remove or similar) and calling it
where needed.

Sean

> +	}
>  
> -	return component_master_add_with_match(dev, &rockchip_drm_ops, match);
> +	ret = component_master_add_with_match(dev, &rockchip_drm_ops, match);
> +	if (ret < 0)
> +		goto err_cleanup_dev_links;
> +
> +	return 0;
> +err_cleanup_dev_links:
> +	list_for_each_entry(link, &dev->links.consumers, s_node)
> +		device_link_del(link);
> +	return ret;
>  }
>  
>  static int rockchip_drm_platform_remove(struct platform_device *pdev)
>  {
> +	struct device_link *link;
> +
>  	component_master_del(&pdev->dev, &rockchip_drm_ops);
>  
> +	list_for_each_entry(link, &pdev->dev.links.consumers, s_node)
> +		device_link_del(link);
> +
>  	return 0;
>  }
>  
> -- 
> 2.11.0
> 
> 

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