linux-kernel - Re: [RFC PATCH 1/4] drm/panfrost: Use GPU_MMU_FEATURES_VA_BITS/PA

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Message-ID: <20250227092100.7e9dfca1@collabora.com>
Date: Thu, 27 Feb 2025 09:21:00 +0100
From: Boris Brezillon <boris.brezillon@...labora.com>
To: Ariel D'Alessandro <ariel.dalessandro@...labora.com>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
 robh@...nel.org, steven.price@....com, maarten.lankhorst@...ux.intel.com,
 mripard@...nel.org, tzimmermann@...e.de, airlied@...il.com, simona@...ll.ch
Subject: Re: [RFC PATCH 1/4] drm/panfrost: Use
 GPU_MMU_FEATURES_VA_BITS/PA_BITS macros

On Wed, 26 Feb 2025 15:30:40 -0300
Ariel D'Alessandro <ariel.dalessandro@...labora.com> wrote:

> As done in panthor, define and use these GPU_MMU_FEATURES_* macros,
> which makes code easier to read and reuse.
> 
> Signed-off-by: Ariel D'Alessandro <ariel.dalessandro@...labora.com>

Reviewed-by: Boris Brezillon <boris.brezillon@...labora.com>

> ---
>  drivers/gpu/drm/panfrost/panfrost_mmu.c  | 6 ++++--
>  drivers/gpu/drm/panfrost/panfrost_regs.h | 2 ++
>  2 files changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c b/drivers/gpu/drm/panfrost/panfrost_mmu.c
> index b91019cd5acb..7df2c8d5b0ae 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_mmu.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c
> @@ -615,6 +615,8 @@ static void panfrost_drm_mm_color_adjust(const struct drm_mm_node *node,
>  
>  struct panfrost_mmu *panfrost_mmu_ctx_create(struct panfrost_device *pfdev)
>  {
> +	u32 va_bits = GPU_MMU_FEATURES_VA_BITS(pfdev->features.mmu_features);
> +	u32 pa_bits = GPU_MMU_FEATURES_PA_BITS(pfdev->features.mmu_features);
>  	struct panfrost_mmu *mmu;
>  
>  	mmu = kzalloc(sizeof(*mmu), GFP_KERNEL);
> @@ -633,8 +635,8 @@ struct panfrost_mmu *panfrost_mmu_ctx_create(struct panfrost_device *pfdev)
>  
>  	mmu->pgtbl_cfg = (struct io_pgtable_cfg) {
>  		.pgsize_bitmap	= SZ_4K | SZ_2M,
> -		.ias		= FIELD_GET(0xff, pfdev->features.mmu_features),
> -		.oas		= FIELD_GET(0xff00, pfdev->features.mmu_features),
> +		.ias		= va_bits,
> +		.oas		= pa_bits,
>  		.coherent_walk	= pfdev->coherent,
>  		.tlb		= &mmu_tlb_ops,
>  		.iommu_dev	= pfdev->dev,
> diff --git a/drivers/gpu/drm/panfrost/panfrost_regs.h b/drivers/gpu/drm/panfrost/panfrost_regs.h
> index c7bba476ab3f..b5f279a19a08 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_regs.h
> +++ b/drivers/gpu/drm/panfrost/panfrost_regs.h
> @@ -16,6 +16,8 @@
>  #define   GROUPS_L2_COHERENT		BIT(0)	/* Cores groups are l2 coherent */
>  
>  #define GPU_MMU_FEATURES		0x014	/* (RO) MMU features */
> +#define  GPU_MMU_FEATURES_VA_BITS(x)	((x) & GENMASK(7, 0))
> +#define  GPU_MMU_FEATURES_PA_BITS(x)	(((x) >> 8) & GENMASK(7, 0))
>  #define GPU_AS_PRESENT			0x018	/* (RO) Address space slots present */
>  #define GPU_JS_PRESENT			0x01C	/* (RO) Job slots present */
>