Hi Adrián,
On Sat, Aug 17, 2024 at 11:10:17AM +0200, Boris Brezillon wrote:
> On Fri, 16 Aug 2024 19:52:49 +0100
> Adrián Larumbe <adrian.larumbe@xxxxxxxxxxxxx> 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.
> >
> > Signed-off-by: Adrián Larumbe <adrian.larumbe@xxxxxxxxxxxxx>
>
> We probably want Fixes/Cc-stable tags here.
>
> > ---
> > drivers/gpu/drm/panthor/panthor_fw.c | 8 +++++++-
> > drivers/gpu/drm/panthor/panthor_mmu.c | 19 ++++++++++++++++---
> > drivers/gpu/drm/panthor/panthor_mmu.h | 1 +
> > 3 files changed, 24 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..a77ee5ce691d 100644
> > --- a/drivers/gpu/drm/panthor/panthor_mmu.c
> > +++ b/drivers/gpu/drm/panthor/panthor_mmu.c
> > @@ -874,14 +874,27 @@ 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);
> > + /*
> > + * If we made it this far, that means the device is awake, because
> > + * upon device suspension, all active VMs are given an AS id of -1
> > + */
> > + ret = mmu_hw_do_operation(vm, iova, size, AS_COMMAND_FLUSH_PT);
>
> I would normally prefer this change to be in its own commit, but given
> this is needed to be able to flush caches in the resume path, I'm fine
> keeping it in the same patch. The comment is a bit odd now that you
> dropped the pm_runtime_active() call though. I would rather have a
> comment in mmu_hw_do_operation_locked(), after the AS ID check
> explaining that as.id >= 0 guarantees that the HW is up and running,
> and that we can proceed with the flush operation without calling
> pm_runtime_active().
Given Boris' comments, are you planning on sending a v2?
Best regards,
Liviu
>
> >
> > 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);
>
--
====================
| I would like to |
| fix the world, |
| but they're not |
| giving me the |
\ source code! /
---------------
¯\_(ツ)_/¯
