Commit f352262f authored by Robin Murphy's avatar Robin Murphy Committed by Steven Price
Browse files

drm/panfrost: Split io-pgtable requests properly 



Although we don't use 1GB block mappings, we still need to split
map/unmap requests at 1GB boundaries to match what io-pgtable expects.
Fix that, and add some explanation to make sense of it all.

Fixes: 3740b081 ("drm/panfrost: Update io-pgtable API")
Reported-by: default avatarDmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: default avatarRobin Murphy <robin.murphy@arm.com>
Tested-by: default avatarDmitry Osipenko <dmitry.osipenko@collabora.com>
Reviewed-by: default avatarSteven Price <steven.price@arm.com>
Signed-off-by: default avatarSteven Price <steven.price@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/49e54bb4019cd06e01549b106d7ac37c3d182cd3.1667927179.git.robin.murphy@arm.com
parent e0b26b94

drivers/gpu/drm/panfrost/panfrost_mmu.c

+10 −1
Original line number Diff line number Diff line
@@ -250,13 +250,22 @@ void panfrost_mmu_reset(struct panfrost_device *pfdev) 


static size_t get_pgsize(u64 addr, size_t size, size_t *count)

{

	/*

	 * io-pgtable only operates on multiple pages within a single table

	 * entry, so we need to split at boundaries of the table size, i.e.

	 * the next block size up. The distance from address A to the next

	 * boundary of block size B is logically B - A % B, but in unsigned

	 * two's complement where B is a power of two we get the equivalence

	 * B - A % B == (B - A) % B == (n * B - A) % B, and choose n = 0 :)

	 */

	size_t blk_offset = -addr % SZ_2M;



	if (blk_offset || size < SZ_2M) {

		*count = min_not_zero(blk_offset, size) / SZ_4K;

		return SZ_4K;

	}

	*count = size / SZ_2M;

	blk_offset = -addr % SZ_1G ?: SZ_1G;

	*count = min(blk_offset, size) / SZ_2M;

	return SZ_2M;

}