linux-kernel - Re: [PATCH 2/3] drm/panfrost: Use u64 for size in lock

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Date:   Mon, 23 Aug 2021 10:40:53 +0100
From:   Steven Price <steven.price@....com>
To:     Alyssa Rosenzweig <alyssa.rosenzweig@...labora.com>,
        dri-devel@...ts.freedesktop.org
Cc:     Rob Herring <robh@...nel.org>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, linux-kernel@...r.kernel.org,
        Chris Morgan <macromorgan@...mail.com>
Subject: Re: [PATCH 2/3] drm/panfrost: Use u64 for size in lock_region

On 20/08/2021 22:31, Alyssa Rosenzweig wrote:
> Mali virtual addresses are 48-bit. Use a u64 instead of size_t to ensure
> we can express the "lock everything" condition as ~0ULL without relying
> on platform-specific behaviour.

'platform-specific behaviour' makes it sound like this is something to
do with a particular board. This is 32bit/64bit - it's going to be
broken on 32bit: large lock regions are not going to work.

> Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@...labora.com>
> Suggested-by: Rob Herring <robh@...nel.org>
> Tested-by: Chris Morgan <macromorgan@...mail.com>

Fixes: f3ba91228e8e ("drm/panfrost: Add initial panfrost driver")

Reviewed-by: Steven Price <steven.price@....com>

Steve

> ---
>  drivers/gpu/drm/panfrost/panfrost_mmu.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c b/drivers/gpu/drm/panfrost/panfrost_mmu.c
> index f6e02d0392f4..3a795273e505 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_mmu.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c
> @@ -58,7 +58,7 @@ static int write_cmd(struct panfrost_device *pfdev, u32 as_nr, u32 cmd)
>  }
>  
>  static void lock_region(struct panfrost_device *pfdev, u32 as_nr,
> -			u64 iova, size_t size)
> +			u64 iova, u64 size)
>  {
>  	u8 region_width;
>  	u64 region = iova & PAGE_MASK;
> @@ -78,7 +78,7 @@ static void lock_region(struct panfrost_device *pfdev, u32 as_nr,
>  
>  
>  static int mmu_hw_do_operation_locked(struct panfrost_device *pfdev, int as_nr,
> -				      u64 iova, size_t size, u32 op)
> +				      u64 iova, u64 size, u32 op)
>  {
>  	if (as_nr < 0)
>  		return 0;
> @@ -95,7 +95,7 @@ static int mmu_hw_do_operation_locked(struct panfrost_device *pfdev, int as_nr,
>  
>  static int mmu_hw_do_operation(struct panfrost_device *pfdev,
>  			       struct panfrost_mmu *mmu,
> -			       u64 iova, size_t size, u32 op)
> +			       u64 iova, u64 size, u32 op)
>  {
>  	int ret;
>  
> @@ -112,7 +112,7 @@ static void panfrost_mmu_enable(struct panfrost_device *pfdev, struct panfrost_m
>  	u64 transtab = cfg->arm_mali_lpae_cfg.transtab;
>  	u64 memattr = cfg->arm_mali_lpae_cfg.memattr;
>  
> -	mmu_hw_do_operation_locked(pfdev, as_nr, 0, ~0UL, AS_COMMAND_FLUSH_MEM);
> +	mmu_hw_do_operation_locked(pfdev, as_nr, 0, ~0ULL, AS_COMMAND_FLUSH_MEM);
>  
>  	mmu_write(pfdev, AS_TRANSTAB_LO(as_nr), transtab & 0xffffffffUL);
>  	mmu_write(pfdev, AS_TRANSTAB_HI(as_nr), transtab >> 32);
> @@ -128,7 +128,7 @@ static void panfrost_mmu_enable(struct panfrost_device *pfdev, struct panfrost_m
>  
>  static void panfrost_mmu_disable(struct panfrost_device *pfdev, u32 as_nr)
>  {
> -	mmu_hw_do_operation_locked(pfdev, as_nr, 0, ~0UL, AS_COMMAND_FLUSH_MEM);
> +	mmu_hw_do_operation_locked(pfdev, as_nr, 0, ~0ULL, AS_COMMAND_FLUSH_MEM);
>  
>  	mmu_write(pfdev, AS_TRANSTAB_LO(as_nr), 0);
>  	mmu_write(pfdev, AS_TRANSTAB_HI(as_nr), 0);
> @@ -242,7 +242,7 @@ static size_t get_pgsize(u64 addr, size_t size)
>  
>  static void panfrost_mmu_flush_range(struct panfrost_device *pfdev,
>  				     struct panfrost_mmu *mmu,
> -				     u64 iova, size_t size)
> +				     u64 iova, u64 size)
>  {
>  	if (mmu->as < 0)
>  		return;
>