linux-kernel - [PATCH 7/8] drm/panthor: Improve IOMMU map/unmap debugging logs

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Message-ID: <20250929200316.18417-8-loic.molinari@collabora.com>
Date: Mon, 29 Sep 2025 22:03:15 +0200
From: Loïc Molinari <loic.molinari@...labora.com>
To: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	Jani Nikula <jani.nikula@...ux.intel.com>,
	Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
	Rodrigo Vivi <rodrigo.vivi@...el.com>,
	Tvrtko Ursulin <tursulin@...ulin.net>,
	Boris Brezillon <boris.brezillon@...labora.com>,
	Rob Herring <robh@...nel.org>,
	Steven Price <steven.price@....com>,
	Liviu Dudau <liviu.dudau@....com>,
	Melissa Wen <mwen@...lia.com>,
	Maíra Canal <mcanal@...lia.com>,
	Hugh Dickins <hughd@...gle.com>,
	Baolin Wang <baolin.wang@...ux.alibaba.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Loïc Molinari <loic.molinari@...labora.com>,
	Al Viro <viro@...iv.linux.org.uk>,
	Mikołaj Wasiak <mikolaj.wasiak@...el.com>,
	Christian Brauner <brauner@...nel.org>,
	Nitin Gote <nitin.r.gote@...el.com>,
	Andi Shyti <andi.shyti@...ux.intel.com>
Cc: linux-kernel@...r.kernel.org,
	dri-devel@...ts.freedesktop.org,
	intel-gfx@...ts.freedesktop.org,
	linux-mm@...ck.org,
	kernel@...labora.com
Subject: [PATCH 7/8] drm/panthor: Improve IOMMU map/unmap debugging logs

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@...labora.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