Re: [PATCH v3 23/25] drm/xe: Compute dumb-buffer sizes with drm_mode_size_dumb()

From: Matthew Auld <matthew.auld@intel.com>
To: Thomas Zimmermann <tzimmermann@suse.de>,
	maarten.lankhorst@linux.intel.com, mripard@kernel.org,
	airlied@gmail.com, simona@ffwll.ch
Cc: dri-devel@lists.freedesktop.org,
	linux-mediatek@lists.infradead.org,
	freedreno@lists.freedesktop.org, linux-arm-msm@vger.kernel.org,
	imx@lists.linux.dev, linux-samsung-soc@vger.kernel.org,
	nouveau@lists.freedesktop.org, virtualization@lists.linux.dev,
	spice-devel@lists.freedesktop.org,
	linux-renesas-soc@vger.kernel.org,
	linux-rockchip@lists.infradead.org, linux-tegra@vger.kernel.org,
	intel-xe@lists.freedesktop.org, xen-devel@lists.xenproject.org,
	"Lucas De Marchi" <lucas.demarchi@intel.com>,
	"Thomas Hellström" <thomas.hellstrom@linux.intel.com>,
	"Rodrigo Vivi" <rodrigo.vivi@intel.com>
Subject: Re: [PATCH v3 23/25] drm/xe: Compute dumb-buffer sizes with drm_mode_size_dumb()
Date: Thu, 20 Feb 2025 10:08:33 +0000	[thread overview]
Message-ID: <92c1b182-5a0b-4d13-9b16-172ac970b62e@intel.com> (raw)
In-Reply-To: <20250218142542.438557-24-tzimmermann@suse.de>

On 18/02/2025 14:23, Thomas Zimmermann wrote:
> Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch
> and buffer size. Align the pitch to a multiple of 8. Align the
> buffer size according to hardware requirements.
> 
> Xe's internal calculation allowed for 64-bit wide buffer sizes, but
> the ioctl's internal checks always verified against 32-bit wide limits.
> Hance, it is safe to limit the driver code to 32-bit calculations as
> well.
> 
> v3:
> - mention 32-bit calculation in commit description (Matthew)
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> Cc: Lucas De Marchi <lucas.demarchi@intel.com>
> Cc: "Thomas Hellström" <thomas.hellstrom@linux.intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>


> ---
>   drivers/gpu/drm/xe/xe_bo.c | 8 ++++----
>   1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
> index 78d09c5ed26d..b34f446ad57d 100644
> --- a/drivers/gpu/drm/xe/xe_bo.c
> +++ b/drivers/gpu/drm/xe/xe_bo.c
> @@ -9,6 +9,7 @@
>   #include <linux/nospec.h>
>   
>   #include <drm/drm_drv.h>
> +#include <drm/drm_dumb_buffers.h>
>   #include <drm/drm_gem_ttm_helper.h>
>   #include <drm/drm_managed.h>
>   #include <drm/ttm/ttm_device.h>
> @@ -2672,14 +2673,13 @@ int xe_bo_dumb_create(struct drm_file *file_priv,
>   	struct xe_device *xe = to_xe_device(dev);
>   	struct xe_bo *bo;
>   	uint32_t handle;
> -	int cpp = DIV_ROUND_UP(args->bpp, 8);
>   	int err;
>   	u32 page_size = max_t(u32, PAGE_SIZE,
>   		xe->info.vram_flags & XE_VRAM_FLAGS_NEED64K ? SZ_64K : SZ_4K);
>   
> -	args->pitch = ALIGN(args->width * cpp, 64);
> -	args->size = ALIGN(mul_u32_u32(args->pitch, args->height),
> -			   page_size);
> +	err = drm_mode_size_dumb(dev, args, SZ_64, page_size);
> +	if (err)
> +		return err;
>   
>   	bo = xe_bo_create_user(xe, NULL, NULL, args->size,
>   			       DRM_XE_GEM_CPU_CACHING_WC,


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