On 02/09/2024 14:02, Adrián Larumbe wrote:
> In the off-chance that waiting for the firmware to signal its booted status
> timed out in the fast reset path, one must flush the cache lines for the
> entire FW VM address space before reloading the regions, otherwise stale
> values eventually lead to a scheduler job timeout.
>
> Fixes: 647810ec2476 ("drm/panthor: Add the MMU/VM logical block")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Adrián Larumbe <adrian.larumbe@xxxxxxxxxxxxx>
> Acked-by: Liviu Dudau <liviu.dudau@xxxxxxx>
Reviewed-by: Steven Price <steven.price@xxxxxxx>
> ---
> drivers/gpu/drm/panthor/panthor_fw.c | 8 +++++++-
> drivers/gpu/drm/panthor/panthor_mmu.c | 21 ++++++++++++++++++---
> drivers/gpu/drm/panthor/panthor_mmu.h | 1 +
> 3 files changed, 26 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/panthor/panthor_fw.c b/drivers/gpu/drm/panthor/panthor_fw.c
> index 857f3f11258a..ef232c0c2049 100644
> --- a/drivers/gpu/drm/panthor/panthor_fw.c
> +++ b/drivers/gpu/drm/panthor/panthor_fw.c
> @@ -1089,6 +1089,12 @@ int panthor_fw_post_reset(struct panthor_device *ptdev)
> panthor_fw_stop(ptdev);
> ptdev->fw->fast_reset = false;
> drm_err(&ptdev->base, "FW fast reset failed, trying a slow reset");
> +
> + ret = panthor_vm_flush_all(ptdev->fw->vm);
> + if (ret) {
> + drm_err(&ptdev->base, "FW slow reset failed (couldn't flush FW's AS l2cache)");
> + return ret;
> + }
> }
>
> /* Reload all sections, including RO ones. We're not supposed
> @@ -1099,7 +1105,7 @@ int panthor_fw_post_reset(struct panthor_device *ptdev)
>
> ret = panthor_fw_start(ptdev);
> if (ret) {
> - drm_err(&ptdev->base, "FW slow reset failed");
> + drm_err(&ptdev->base, "FW slow reset failed (couldn't start the FW )");
> return ret;
> }
>
> diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c
> index d47972806d50..bbc12728437f 100644
> --- a/drivers/gpu/drm/panthor/panthor_mmu.c
> +++ b/drivers/gpu/drm/panthor/panthor_mmu.c
> @@ -576,6 +576,12 @@ static int mmu_hw_do_operation_locked(struct panthor_device *ptdev, int as_nr,
> if (as_nr < 0)
> return 0;
>
> + /*
> + * If the AS number is greater than zero, then we can be sure
> + * the device is up and running, so we don't need to explicitly
> + * power it up
> + */
> +
> if (op != AS_COMMAND_UNLOCK)
> lock_region(ptdev, as_nr, iova, size);
>
> @@ -874,14 +880,23 @@ static int panthor_vm_flush_range(struct panthor_vm *vm, u64 iova, u64 size)
> if (!drm_dev_enter(&ptdev->base, &cookie))
> return 0;
>
> - /* Flush the PTs only if we're already awake */
> - if (pm_runtime_active(ptdev->base.dev))
> - ret = mmu_hw_do_operation(vm, iova, size, AS_COMMAND_FLUSH_PT);
> + ret = mmu_hw_do_operation(vm, iova, size, AS_COMMAND_FLUSH_PT);
>
> drm_dev_exit(cookie);
> return ret;
> }
>
> +/**
> + * panthor_vm_flush_all() - Flush L2 caches for the entirety of a VM's AS
> + * @vm: VM whose cache to flush
> + *
> + * Return: 0 on success, a negative error code if flush failed.
> + */
> +int panthor_vm_flush_all(struct panthor_vm *vm)
> +{
> + return panthor_vm_flush_range(vm, vm->base.mm_start, vm->base.mm_range);
> +}
> +
> static int panthor_vm_unmap_pages(struct panthor_vm *vm, u64 iova, u64 size)
> {
> struct panthor_device *ptdev = vm->ptdev;
> diff --git a/drivers/gpu/drm/panthor/panthor_mmu.h b/drivers/gpu/drm/panthor/panthor_mmu.h
> index f3c1ed19f973..6788771071e3 100644
> --- a/drivers/gpu/drm/panthor/panthor_mmu.h
> +++ b/drivers/gpu/drm/panthor/panthor_mmu.h
> @@ -31,6 +31,7 @@ panthor_vm_get_bo_for_va(struct panthor_vm *vm, u64 va, u64 *bo_offset);
> int panthor_vm_active(struct panthor_vm *vm);
> void panthor_vm_idle(struct panthor_vm *vm);
> int panthor_vm_as(struct panthor_vm *vm);
> +int panthor_vm_flush_all(struct panthor_vm *vm);
>
> struct panthor_heap_pool *
> panthor_vm_get_heap_pool(struct panthor_vm *vm, bool create);
