linux-kernel - Re: [PATCH v2 24/25] drm/mediatek: respect page offset for PRIME mmap calls

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Message-ID: <1555403634.11519.11.camel@mtksdaap41>
Date:   Tue, 16 Apr 2019 16:33:54 +0800
From:   CK Hu <ck.hu@...iatek.com>
To:     <yongqiang.niu@...iatek.com>
CC:     <p.zabel@...gutronix.de>, <robh+dt@...nel.org>,
        <matthias.bgg@...il.com>, <airlied@...ux.ie>,
        <mark.rutland@....com>, <dri-devel@...ts.freedesktop.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>, <Bibby.Hsieh@...iatek.com>,
        <yt.shen@...iatek.com>
Subject: Re: [PATCH v2 24/25] drm/mediatek: respect page offset for PRIME
 mmap calls

Hi, Yongqiang:

On Wed, 2019-03-27 at 14:19 +0800, yongqiang.niu@...iatek.com wrote:
> From: Yongqiang Niu <yongqiang.niu@...iatek.com>
> 
> Respect page offset for PRIME mmap calls

Reviewed-by: CK Hu <ck.hu@...iatek.com>

> 
> Signed-off-by: Yongqiang Niu <yongqiang.niu@...iatek.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_drm_gem.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_drm_gem.c b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> index c230237..524e494 100644
> --- a/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> +++ b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> @@ -144,7 +144,6 @@ static int mtk_drm_gem_object_mmap(struct drm_gem_object *obj,
>  	 * VM_PFNMAP flag that was set by drm_gem_mmap_obj()/drm_gem_mmap().
>  	 */
>  	vma->vm_flags &= ~VM_PFNMAP;
> -	vma->vm_pgoff = 0;
>  
>  	ret = dma_mmap_attrs(priv->dma_dev, vma, mtk_gem->cookie,
>  			     mtk_gem->dma_addr, obj->size, mtk_gem->dma_attrs);
> @@ -183,6 +182,12 @@ int mtk_drm_gem_mmap(struct file *filp, struct vm_area_struct *vma)
>  
>  	obj = vma->vm_private_data;
>  
> +	/*
> +	 * Set vm_pgoff (used as a fake buffer offset by DRM) to 0 and map the
> +	 * whole buffer from the start.
> +	 */
> +	vma->vm_pgoff = 0;
> +
>  	return mtk_drm_gem_object_mmap(obj, vma);
>  }
>