[PATCH v5 10/12] drm/panthor: Improve IOMMU map/unmap debugging logs

Loïc Molinari
2025-10-21T11:31:07Z

Log the number of pages and their sizes actually mapped/unmapped by
the IOMMU page table driver. Since a map/unmap op is often split in
several ops depending on the underlying scatter/gather table, add the
start address and the total size to the debugging logs in order to
help understand which batch an op is part of.

Signed-off-by: Loïc Molinari <loic.molinari@collabora.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
---
drivers/gpu/drm/panthor/panthor_mmu.c | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c
index 6dec4354e378..aefbd83d1a75 100644
--- a/drivers/gpu/drm/panthor/panthor_mmu.c
+++ b/drivers/gpu/drm/panthor/panthor_mmu.c
@@ -917,10 +917,9 @@ static int panthor_vm_unmap_pages(struct panthor_vm *vm, u64 iova, u64 size)
{
struct panthor_device *ptdev = vm->ptdev;
struct io_pgtable_ops *ops = vm->pgtbl_ops;
+ u64 start_iova = iova;
u64 offset = 0;

- drm_dbg(&ptdev->base, "unmap: as=%d, iova=%llx, len=%llx", vm->as.id, iova, size);
-
while (offset < size) {
size_t unmapped_sz = 0, pgcount;
size_t pgsize = get_pgsize(iova + offset, size - offset, &pgcount);
@@ -935,6 +934,12 @@ static int panthor_vm_unmap_pages(struct panthor_vm *vm, u64 iova, u64 size)
panthor_vm_flush_range(vm, iova, offset + unmapped_sz);
return -EINVAL;
}
+
+ drm_dbg(&ptdev->base,
+ "unmap: as=%d, iova=0x%llx, sz=%llu, va=0x%llx, pgcnt=%zu, pgsz=%zu",
+ vm->as.id, start_iova, size, iova + offset,
+ unmapped_sz / pgsize, pgsize);
+
offset += unmapped_sz;
}

@@ -950,6 +955,7 @@ panthor_vm_map_pages(struct panthor_vm *vm, u64 iova, int prot,
struct scatterlist *sgl;
struct io_pgtable_ops *ops = vm->pgtbl_ops;
u64 start_iova = iova;
+ u64 start_size = size;
int ret;

if (!size)
@@ -969,15 +975,18 @@ panthor_vm_map_pages(struct panthor_vm *vm, u64 iova, int prot,
len = min_t(size_t, len, size);
size -= len;

- drm_dbg(&ptdev->base, "map: as=%d, iova=%llx, paddr=%pad, len=%zx",
- vm->as.id, iova, &paddr, len);
-
while (len) {
size_t pgcount, mapped = 0;
size_t pgsize = get_pgsize(iova | paddr, len, &pgcount);

ret = ops->map_pages(ops, iova, paddr, pgsize, pgcount, prot,
GFP_KERNEL, &mapped);
+
+ drm_dbg(&ptdev->base,
+ "map: as=%d, iova=0x%llx, sz=%llu, va=0x%llx, pa=%pad, pgcnt=%zu, pgsz=%zu",
+ vm->as.id, start_iova, start_size, iova, &paddr,
+ mapped / pgsize, pgsize);
+
iova += mapped;
paddr += mapped;
len -= mapped;
--
2.47.3