linux-kernel - Re: [PATCH] drm/stm: check pitch and size calculations even if !CONFIG

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Date:   Tue, 30 Jan 2018 20:02:21 +0000
From:   Philippe CORNU <philippe.cornu@...com>
To:     Benjamin Gaignard <benjamin.gaignard@...aro.org>,
        Yannick FERTRE <yannick.fertre@...com>,
        Vincent ABRIOU <vincent.abriou@...com>,
        "laurent.pinchart@...asonboard.com" 
        <laurent.pinchart@...asonboard.com>
CC:     "airlied@...ux.ie" <airlied@...ux.ie>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/stm: check pitch and size calculations even if
 !CONFIG_MMU

Hi Benjamin,

Working on a coming patch (based on the new has_alpha field in fourcc), 
I realized that in particular cases (2 layers + "odd" layer sizes) 
memory transfers on MCU are greatly improved too if drm buffers are 
aligned on 128 bytes : )

So I suggest to cancel this patch.

Then you can post a new one removing ifdef CONFIG_MMU endif, or I can do 
it, it is up to you.

Many thanks for your support,
Philippe :-)

On 01/30/2018 04:24 PM, Benjamin Gaignard wrote:
> In all cases we have to check pitch and size calculations.
> Rely on drm_gem_cma_dumb_create for no MMU cases.
> 
> Fixes: 21f815bf773c ("drm/stm: drv: Improve data transfers")
> 
> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@...aro.org>
> ---
>   drivers/gpu/drm/stm/drv.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/stm/drv.c b/drivers/gpu/drm/stm/drv.c
> index 8bc7e8418b8d..3e0fb5f34b8e 100644
> --- a/drivers/gpu/drm/stm/drv.c
> +++ b/drivers/gpu/drm/stm/drv.c
> @@ -44,9 +44,11 @@ static int stm_gem_cma_dumb_create(struct drm_file *file,
>   	 */
>   	args->pitch = roundup(min_pitch, 128);
>   	args->height = roundup(args->height, 4);
> -#endif
>   
>   	return drm_gem_cma_dumb_create_internal(file, dev, args);
> +#else
> +	return drm_gem_cma_dumb_create(file, dev, args);
> +#endif
>   }
>   
>   DEFINE_DRM_GEM_CMA_FOPS(drv_driver_fops);
>