On 20/08/2021 22:31, Alyssa Rosenzweig wrote: > When locking a region, we currently clamp to a PAGE_SIZE as the minimum > lock region. While this is valid for Midgard, it is invalid for Bifrost, While the spec does seem to state it's invalid for Bifrost - kbase didn't bother with a lower clamp for a long time. I actually think this is in many ways more of a spec bug: i.e. implementation details of the round-up that the hardware does. But it's much safer following the spec ;) And it seems like kbase eventually caught up too. > where the minimum locking size is 8x larger than the 4k page size. Add a > hardware definition for the minimum lock region size (corresponding to > KBASE_LOCK_REGION_MIN_SIZE_LOG2 in kbase) and respect it. > > Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@xxxxxxxxxxxxx> > Tested-by: Chris Morgan <macromorgan@xxxxxxxxxxx> > Cc: <stable@xxxxxxxxxxxxxxx> Reviewed-by: Steven Price <steven.price@xxxxxxx> > --- > drivers/gpu/drm/panfrost/panfrost_mmu.c | 2 +- > drivers/gpu/drm/panfrost/panfrost_regs.h | 2 ++ > 2 files changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c b/drivers/gpu/drm/panfrost/panfrost_mmu.c > index 3a795273e505..dfe5f1d29763 100644 > --- a/drivers/gpu/drm/panfrost/panfrost_mmu.c > +++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c > @@ -66,7 +66,7 @@ static void lock_region(struct panfrost_device *pfdev, u32 as_nr, > /* The size is encoded as ceil(log2) minus(1), which may be calculated > * with fls. The size must be clamped to hardware bounds. > */ > - size = max_t(u64, size, PAGE_SIZE); > + size = max_t(u64, size, AS_LOCK_REGION_MIN_SIZE); > region_width = fls64(size - 1) - 1; > region |= region_width; > > diff --git a/drivers/gpu/drm/panfrost/panfrost_regs.h b/drivers/gpu/drm/panfrost/panfrost_regs.h > index 1940ff86e49a..6c5a11ef1ee8 100644 > --- a/drivers/gpu/drm/panfrost/panfrost_regs.h > +++ b/drivers/gpu/drm/panfrost/panfrost_regs.h > @@ -316,6 +316,8 @@ > #define AS_FAULTSTATUS_ACCESS_TYPE_READ (0x2 << 8) > #define AS_FAULTSTATUS_ACCESS_TYPE_WRITE (0x3 << 8) > > +#define AS_LOCK_REGION_MIN_SIZE (1ULL << 15) > + > #define gpu_write(dev, reg, data) writel(data, dev->iomem + reg) > #define gpu_read(dev, reg) readl(dev->iomem + reg) > >
