linux-kernel - Re: [Re-send][PATCH] gpu/drm: remove drm_modeset_lock protection for drm

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Message-ID: <20200903084531.GJ2352366@phenom.ffwll.local>
Date:   Thu, 3 Sep 2020 10:45:31 +0200
From:   Daniel Vetter <daniel@...ll.ch>
To:     Bernard <bernard@...o.com>
Cc:     Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        opensource.kernel@...o.com
Subject: Re: [Re-send][PATCH] gpu/drm: remove drm_modeset_lock protection for
 drm_error

On Wed, Sep 02, 2020 at 09:17:02PM +0800, Bernard wrote:
> In function drm_atomic_helper_shutdown, maybe there is no need
> to protect DRM_ERROR log in DRM_MODESET_LOCK_ALL_BEGIN &
> DRM_MODESET_LOCK_ALL_END. This change is to make code run a bit
> fast.
> 
> Signed-off-by: Bernard Zhao <bernard@...o.com>

This is only run at driver unload, so really no need to optimize anything
for speed. And I think this change makes the code less symmetric, so not
really worth it imo.

Similar with the via change, drm/via is very very legacy code where the
next step will be to just outright delete it all.

Thanks anyway for submitting the patches, in other places such a change
would indeed make sense I think.
-Daniel

> ---
>  drivers/gpu/drm/drm_atomic_helper.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> index 85d163f16801..8902fd6316fc 100644
> --- a/drivers/gpu/drm/drm_atomic_helper.c
> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> @@ -3100,12 +3100,10 @@ void drm_atomic_helper_shutdown(struct drm_device *dev)
>  	int ret;
>  
>  	DRM_MODESET_LOCK_ALL_BEGIN(dev, ctx, 0, ret);
> -
>  	ret = drm_atomic_helper_disable_all(dev, &ctx);
> +	DRM_MODESET_LOCK_ALL_END(ctx, ret);
>  	if (ret)
>  		DRM_ERROR("Disabling all crtc's during unload failed with %i\n", ret);
> -
> -	DRM_MODESET_LOCK_ALL_END(ctx, ret);
>  }
>  EXPORT_SYMBOL(drm_atomic_helper_shutdown);
>  
> -- 
> 2.17.1
> 
> 
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch