[PATCH v2 1/3] drm/xe: Align all 64k VRAM buffers physically when multiple of 64k.

[Zbigniew Kempczyński]

On Wed, Aug 21, 2024 at 10:56:35PM +0200, Maarten Lankhorst wrote:
> For CCS formats on affected platforms, CCS can be used freely, but
> display engine requires a multiple of 64k physical pages. No other
> changes are needed.
> 
> At the BO creation time we don't know if the BO will be used for CCS
> or not. If the scanout flag is set, and the BO is a multiple of 64k,
> we take the safe route and force the physical alignment of 64k pages.
> 
> If the BO is not a multiple of 64k, or the scanout flag was not set
> at BO creation, we reject it for usage as CCS in display. The physical
> pages are likely not aligned correctly, and this will cause corruption
> when used as FB.
> 
> This is a slightly different approach from my previous patch. Instead
> of requiring a scanout flag at FB creation, we now make all buffers of
> the right size physically aligned correctly, so no change from userspace
> is needed.
> 
> It will be interesting to see if it affects performance in any way,
> could potentially even improve things with 64k PTE's.
> 
> Inspired by Zbigniews patch.
> 
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> Co-developed-by: Zbigniew Kempczyński <zbigniew.kempczynski at intel.com>
> Cc: Matthew Auld <matthew.auld at intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
> Cc: Thomas Hellström <thomas.hellstrom at linux.intel.com>
> Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> Cc: Juha-Pekka Heikkilä <juha-pekka.heikkila at intel.com>
> ---
>  drivers/gpu/drm/xe/display/intel_fb_bo.c |  6 ++++++
>  drivers/gpu/drm/xe/xe_bo.c               | 10 ++++++++++
>  drivers/gpu/drm/xe/xe_device_types.h     |  1 +
>  drivers/gpu/drm/xe/xe_vm.c               |  3 ++-
>  4 files changed, 19 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/xe/display/intel_fb_bo.c b/drivers/gpu/drm/xe/display/intel_fb_bo.c
> index f835492f73fb4..407367719abe2 100644
> --- a/drivers/gpu/drm/xe/display/intel_fb_bo.c
> +++ b/drivers/gpu/drm/xe/display/intel_fb_bo.c
> @@ -7,6 +7,7 @@
>  #include <drm/ttm/ttm_bo.h>
>  
>  #include "intel_display_types.h"
> +#include "intel_fb.h"
>  #include "intel_fb_bo.h"
>  #include "xe_bo.h"
>  
> @@ -28,6 +29,11 @@ int intel_fb_bo_framebuffer_init(struct intel_framebuffer *intel_fb,
>  	struct xe_device *xe = to_xe_device(bo->ttm.base.dev);
>  	int ret;
>  
> +	if (XE_IOCTL_DBG(xe, intel_fb_is_ccs_modifier(mode_cmd->modifier[0]) &&
> +			     (xe->info.vram_flags & XE_VRAM_FLAGS_DISPLAY_NEED64K_CCS) &&
> +			     !(bo->flags & XE_BO_FLAG_NEEDS_64K)))
> +		return -EINVAL;

Sth is wrong with intel_fb_is_ccs_modifier(), it is returning false for
kms_ccs crc-primary-basic-4-tiled-bmg-ccs subtest and is not falling
here.

--
Zbigniew

> +>  	xe_bo_get(bo);
>  
>  	ret = ttm_bo_reserve(&bo->ttm, true, false, NULL);
> diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
> index 6ed0e19552159..3a753f4644cb6 100644
> --- a/drivers/gpu/drm/xe/xe_bo.c
> +++ b/drivers/gpu/drm/xe/xe_bo.c
> @@ -2017,6 +2017,16 @@ int xe_gem_create_ioctl(struct drm_device *dev, void *data,
>  	if (args->flags & DRM_XE_GEM_CREATE_FLAG_SCANOUT)
>  		bo_flags |= XE_BO_FLAG_SCANOUT;
>  
> +	/*
> +	 * Lets see what happens if we simply align any buffer that's
> +	 * a multiple of 64k to 64k in places where it's not officially
> +	 * needed.
> +	 */
> +	if ((bo_flags & XE_BO_FLAG_VRAM_MASK) &&
> +	    !(xe->info.vram_flags & XE_VRAM_FLAGS_NEED64K) &&
> +	    !(args->size % SZ_64K))
> +		bo_flags |= XE_BO_FLAG_NEEDS_64K;
> +
>  	bo_flags |= args->placement << (ffs(XE_BO_FLAG_SYSTEM) - 1);
>  
>  	if (args->flags & DRM_XE_GEM_CREATE_FLAG_NEEDS_VISIBLE_VRAM) {
> diff --git a/drivers/gpu/drm/xe/xe_device_types.h b/drivers/gpu/drm/xe/xe_device_types.h
> index 5ed6f5434f42c..12ddab91a01c0 100644
> --- a/drivers/gpu/drm/xe/xe_device_types.h
> +++ b/drivers/gpu/drm/xe/xe_device_types.h
> @@ -47,6 +47,7 @@ struct xe_pat_ops;
>  #define HAS_HECI_CSCFI(xe) ((xe)->info.has_heci_cscfi)
>  
>  #define XE_VRAM_FLAGS_NEED64K		BIT(0)
> +#define XE_VRAM_FLAGS_DISPLAY_NEED64K_CCS	BIT(1)
>  
>  #define XE_GT0		0
>  #define XE_GT1		1
> diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
> index d1bfd0b6e9558..af215f6d6588b 100644
> --- a/drivers/gpu/drm/xe/xe_vm.c
> +++ b/drivers/gpu/drm/xe/xe_vm.c
> @@ -2878,7 +2878,8 @@ static int xe_vm_bind_ioctl_validate_bo(struct xe_device *xe, struct xe_bo *bo,
>  		return -EINVAL;
>  	}
>  
> -	if (bo->flags & XE_BO_FLAG_INTERNAL_64K) {
> +	if ((bo->flags & XE_BO_FLAG_INTERNAL_64K) &&
> +	    (xe->info.vram_flags & XE_VRAM_FLAGS_NEED64K)) {
>  		if (XE_IOCTL_DBG(xe, obj_offset &
>  				 XE_64K_PAGE_MASK) ||
>  		    XE_IOCTL_DBG(xe, addr & XE_64K_PAGE_MASK) ||
> -- 
> 2.45.2
>