Re: [PATCH v10 1/3] drm/xe: Introduced needs_scratch bit in device descriptor

["Ghimiray, Himal Prasad" <himal.prasad.ghimiray@intel.com>]

On 03-04-2025 22:23, Oak Zeng wrote:
> On some platform, scratch page is needed for out of bound prefetch
> to work. Introduce a bit in device descriptor to specify whether
> this device needs scratch page to work.
> 
> v2: introduce a needs_scratch bit in device info (Thomas, Jonathan)
> v3: drop NEEDS_SCRATCH macro (Matt)
> 
> Signed-off-by: Oak Zeng <oak.zeng@intel.com>
> Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> ---
>   drivers/gpu/drm/xe/xe_device_types.h | 2 ++
>   drivers/gpu/drm/xe/xe_pci.c          | 5 +++++
>   2 files changed, 7 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_device_types.h b/drivers/gpu/drm/xe/xe_device_types.h
> index c54adebfe518..e52221389710 100644
> --- a/drivers/gpu/drm/xe/xe_device_types.h
> +++ b/drivers/gpu/drm/xe/xe_device_types.h
> @@ -336,6 +336,8 @@ struct xe_device {
>   		u8 has_usm:1;
>   		/** @info.is_dgfx: is discrete device */
>   		u8 is_dgfx:1;
> +		/** @info.needs_scratch: needs scratch page for oob prefetch to work */
> +		u8 needs_scratch:1;
>   		/**
>   		 * @info.probe_display: Probe display hardware.  If set to
>   		 * false, the driver will behave as if there is no display
> diff --git a/drivers/gpu/drm/xe/xe_pci.c b/drivers/gpu/drm/xe/xe_pci.c
> index 772b6c81672c..ae06c4c13fd7 100644
> --- a/drivers/gpu/drm/xe/xe_pci.c
> +++ b/drivers/gpu/drm/xe/xe_pci.c
> @@ -68,6 +68,7 @@ struct xe_device_desc {
>   	u8 has_llc:1;
>   	u8 has_pxp:1;
>   	u8 has_sriov:1;
> +	u8 needs_scratch:1;
>   	u8 skip_guc_pc:1;
>   	u8 skip_mtcfg:1;
>   	u8 skip_pcode:1;
> @@ -335,6 +336,7 @@ static const struct xe_device_desc lnl_desc = {
>   	.dma_mask_size = 46,
>   	.has_display = true,
>   	.has_pxp = true,
> +	.needs_scratch = true,
>   };
>   
>   static const struct xe_device_desc bmg_desc = {
> @@ -344,6 +346,7 @@ static const struct xe_device_desc bmg_desc = {
>   	.has_display = true,
>   	.has_fan_control = true,
>   	.has_heci_cscfi = 1,
> +	.needs_scratch = true,
>   };
>   
>   static const struct xe_device_desc ptl_desc = {
> @@ -352,6 +355,7 @@ static const struct xe_device_desc ptl_desc = {
>   	.has_display = true,
>   	.has_sriov = true,
>   	.require_force_probe = true,
> +	.needs_scratch = true,
>   };
>   
>   #undef PLATFORM
> @@ -592,6 +596,7 @@ static int xe_info_init_early(struct xe_device *xe,
>   	xe->info.skip_guc_pc = desc->skip_guc_pc;
>   	xe->info.skip_mtcfg = desc->skip_mtcfg;
>   	xe->info.skip_pcode = desc->skip_pcode;
> +	xe->info.needs_scratch = desc->needs_scratch;

Reviewed-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>

>   
>   	xe->info.probe_display = IS_ENABLED(CONFIG_DRM_XE_DISPLAY) &&
>   				 xe_modparam.probe_display &&