linux-kernel - Re: [PATCH 05/10] drm/panthor: rename and document mmu_hw_do_operation

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Message-ID: <ca22f80c-c233-4030-81d1-f425b8c1fb83@arm.com>
Date: Thu, 2 Oct 2025 11:41:33 +0100
From: Steven Price <steven.price@....com>
To: Chia-I Wu <olvaffe@...il.com>,
 Boris Brezillon <boris.brezillon@...labora.com>,
 Liviu Dudau <liviu.dudau@....com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
 Grant Likely <grant.likely@...aro.org>, Heiko Stuebner <heiko@...ech.de>,
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 05/10] drm/panthor: rename and document
 mmu_hw_do_operation_locked

On 16/09/2025 22:08, Chia-I Wu wrote:
> Rename mmu_hw_do_operation_locked to mmu_hw_flush_caches.

This is confusing, you've renamed the _locked variant and left the
wrapper mmu_hw_do_operation() with the old name.

I agree "do operation" isn't a great name, although "flush caches"
sounds to me like it's a function which does the whole cache flush dance
in one go, but it's still the same "one part of a cache flush operation"
code.

Thanks,
Steve

> 
> Signed-off-by: Chia-I Wu <olvaffe@...il.com>
> ---
>  drivers/gpu/drm/panthor/panthor_mmu.c | 22 +++++++++++++++++-----
>  1 file changed, 17 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c
> index 727339d80d37e..7d1645a24129d 100644
> --- a/drivers/gpu/drm/panthor/panthor_mmu.c
> +++ b/drivers/gpu/drm/panthor/panthor_mmu.c
> @@ -622,8 +622,20 @@ static void mmu_hw_cmd_unlock(struct panthor_device *ptdev, u32 as_nr)
>  	write_cmd(ptdev, as_nr, AS_COMMAND_UNLOCK);
>  }
>  
> -static int mmu_hw_do_operation_locked(struct panthor_device *ptdev, int as_nr,
> -				      u64 iova, u64 size, u32 op)
> +/**
> + * mmu_hw_cmd_flush_caches() - Flush and invalidate L2/MMU/LSC caches
> + * @ptdev: Device.
> + * @as_nr: AS to issue command to.
> + * @iova: Start of the region.
> + * @size: Size of the region.
> + * @op: AS_COMMAND_FLUSH_*
> + *
> + * Issue LOCK/GPU_FLUSH_CACHES/UNLOCK commands in order to flush and
> + * invalidate L2/MMU/LSC caches for a region.
> + *
> + * Return: 0 on success, a negative error code otherwise.
> + */
> +static int mmu_hw_flush_caches(struct panthor_device *ptdev, int as_nr, u64 iova, u64 size, u32 op)
>  {
>  	const u32 l2_flush_op = CACHE_CLEAN | CACHE_INV;
>  	u32 lsc_flush_op;
> @@ -680,7 +692,7 @@ static int mmu_hw_do_operation(struct panthor_vm *vm,
>  	int ret;
>  
>  	mutex_lock(&ptdev->mmu->as.slots_lock);
> -	ret = mmu_hw_do_operation_locked(ptdev, vm->as.id, iova, size, op);
> +	ret = mmu_hw_flush_caches(ptdev, vm->as.id, iova, size, op);
>  	mutex_unlock(&ptdev->mmu->as.slots_lock);
>  
>  	return ret;
> @@ -691,7 +703,7 @@ static int panthor_mmu_as_enable(struct panthor_device *ptdev, u32 as_nr,
>  {
>  	int ret;
>  
> -	ret = mmu_hw_do_operation_locked(ptdev, as_nr, 0, ~0ULL, AS_COMMAND_FLUSH_MEM);
> +	ret = mmu_hw_flush_caches(ptdev, as_nr, 0, ~0ULL, AS_COMMAND_FLUSH_MEM);
>  	if (ret)
>  		return ret;
>  
> @@ -702,7 +714,7 @@ static int panthor_mmu_as_disable(struct panthor_device *ptdev, u32 as_nr)
>  {
>  	int ret;
>  
> -	ret = mmu_hw_do_operation_locked(ptdev, as_nr, 0, ~0ULL, AS_COMMAND_FLUSH_MEM);
> +	ret = mmu_hw_flush_caches(ptdev, as_nr, 0, ~0ULL, AS_COMMAND_FLUSH_MEM);
>  	if (ret)
>  		return ret;
>