[v3,6/8] drm/panfrost: Add cache/TLB flush before switching address space
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Message ID 20190826223317.28509-7-robh@kernel.org
State New
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Series
  • panfrost: Locking and runtime PM fixes
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Commit Message

Rob Herring Aug. 26, 2019, 10:33 p.m. UTC
It's not entirely clear if this is required, but add a flush of GPU caches
and TLBs before we change an address space to new page tables.

Fixes: 7282f7645d06 ("drm/panfrost: Implement per FD address spaces")
Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Cc: Steven Price <steven.price@arm.com>
Cc: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Rob Herring <robh@kernel.org>
---
 drivers/gpu/drm/panfrost/panfrost_mmu.c | 2 ++
 1 file changed, 2 insertions(+)
v3:
 - New patch

--
2.20.1

Comments

Robin Murphy Aug. 27, 2019, 11:30 a.m. UTC | #1
On 26/08/2019 23:33, Rob Herring wrote:
> It's not entirely clear if this is required, but add a flush of GPU caches
> and TLBs before we change an address space to new page tables.

This might work out to be partially redundant with some of the revamped 
flushing in #7, but unless it proves to be a performance bottleneck, 
having both does make things seem more robust and easier to reason about.

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

> Fixes: 7282f7645d06 ("drm/panfrost: Implement per FD address spaces")
> Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
> Cc: Steven Price <steven.price@arm.com>
> Cc: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
> Cc: David Airlie <airlied@linux.ie>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Signed-off-by: Rob Herring <robh@kernel.org>
> ---
>   drivers/gpu/drm/panfrost/panfrost_mmu.c | 2 ++
>   1 file changed, 2 insertions(+)
> v3:
>   - New patch
> 
> diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c b/drivers/gpu/drm/panfrost/panfrost_mmu.c
> index 3407b00d0a3a..d1ebde3327fe 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_mmu.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c
> @@ -115,6 +115,8 @@ 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_write(pfdev, AS_TRANSTAB_LO(as_nr), transtab & 0xffffffffUL);
>   	mmu_write(pfdev, AS_TRANSTAB_HI(as_nr), transtab >> 32);
> 
> --
> 2.20.1
>
Steven Price Aug. 28, 2019, 1:17 p.m. UTC | #2
On 26/08/2019 23:33, Rob Herring wrote:
> It's not entirely clear if this is required, but add a flush of GPU caches
> and TLBs before we change an address space to new page tables.
> 
> Fixes: 7282f7645d06 ("drm/panfrost: Implement per FD address spaces")
> Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
> Cc: Steven Price <steven.price@arm.com>
> Cc: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
> Cc: David Airlie <airlied@linux.ie>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Signed-off-by: Rob Herring <robh@kernel.org>

Equally I'm not sure this is required, but it looks like there might be
a path where a AS is reclaimed and then immediately freed (client closes
fd) which would need a flush (with wait) to ensure that translations had
definitely finished. And it won't do any harm, so:

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

Steve

> ---
>  drivers/gpu/drm/panfrost/panfrost_mmu.c | 2 ++
>  1 file changed, 2 insertions(+)
> v3:
>  - New patch
> 
> diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c b/drivers/gpu/drm/panfrost/panfrost_mmu.c
> index 3407b00d0a3a..d1ebde3327fe 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_mmu.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c
> @@ -115,6 +115,8 @@ 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_write(pfdev, AS_TRANSTAB_LO(as_nr), transtab & 0xffffffffUL);
>  	mmu_write(pfdev, AS_TRANSTAB_HI(as_nr), transtab >> 32);
> 
> --
> 2.20.1
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
>

Patch
diff mbox series

diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c b/drivers/gpu/drm/panfrost/panfrost_mmu.c
index 3407b00d0a3a..d1ebde3327fe 100644
--- a/drivers/gpu/drm/panfrost/panfrost_mmu.c
+++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c
@@ -115,6 +115,8 @@  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_write(pfdev, AS_TRANSTAB_LO(as_nr), transtab & 0xffffffffUL);
 	mmu_write(pfdev, AS_TRANSTAB_HI(as_nr), transtab >> 32);