linux-kernel - [PATCH 4/5] drm/nouveau/mmu/tu102: Add support for compressed kinds

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Message-ID: <20251006191329.277485-5-mohamedahmedegypt2001@gmail.com>
Date: Mon,  6 Oct 2025 22:13:27 +0300
From: Mohamed Ahmed <mohamedahmedegypt2001@...il.com>
To: linux-kernel@...r.kernel.org
Cc: dri-devel@...ts.freedesktop.org,
	Mary Guillemard <mary@...y.zone>,
	Faith Ekstrand <faith.ekstrand@...labora.com>,
	Ben Skeggs <bskeggs@...dia.com>,
	Lyude Paul <lyude@...hat.com>,
	Danilo Krummrich <dakr@...nel.org>,
	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>,
	nouveau@...ts.freedesktop.org
Subject: [PATCH 4/5] drm/nouveau/mmu/tu102: Add support for compressed kinds

From: Ben Skeggs <bskeggs@...dia.com>

Allow compressed PTE kinds to be written into PTEs when GSP-RM is
present, rather than reverting to their non-compressed versions.

Signed-off-by: Ben Skeggs <bskeggs@...dia.com>
---
 .../drm/nouveau/nvkm/subdev/mmu/vmmgp100.c    | 46 ++++++++++++++++++-
 1 file changed, 44 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmmgp100.c b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmmgp100.c
index ecff1096a1bb..ed15a4475181 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmmgp100.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmmgp100.c
@@ -109,12 +109,34 @@ gp100_vmm_pgt_pfn(struct nvkm_vmm *vmm, struct nvkm_mmu_pt *pt,
 	nvkm_done(pt->memory);
 }
 
+static inline u64
+gp100_vmm_comptag_nr(u64 size)
+{
+	return size >> 16; /* One comptag per 64KiB VRAM. */
+}
+
+static inline u64
+gp100_vmm_pte_comptagline_base(u64 addr)
+{
+	/* RM allocates enough comptags for all of VRAM, so use a 1:1 mapping. */
+	return (1 + gp100_vmm_comptag_nr(addr)) << 36; /* NV_MMU_VER2_PTE_COMPTAGLINE */
+}
+
+static inline u64
+gp100_vmm_pte_comptagline_incr(u32 page_size)
+{
+	return gp100_vmm_comptag_nr(page_size) << 36; /* NV_MMU_VER2_PTE_COMPTAGLINE */
+}
+
 static inline void
 gp100_vmm_pgt_pte(struct nvkm_vmm *vmm, struct nvkm_mmu_pt *pt,
 		  u32 ptei, u32 ptes, struct nvkm_vmm_map *map, u64 addr)
 {
 	u64 data = (addr >> 4) | map->type;
 
+	if (map->ctag)
+		data |= gp100_vmm_pte_comptagline_base(addr);
+
 	while (ptes--) {
 		VMM_WO064(pt, vmm, ptei++ * 8, data);
 		data += map->next;
@@ -195,6 +217,9 @@ gp100_vmm_pd0_pte(struct nvkm_vmm *vmm, struct nvkm_mmu_pt *pt,
 {
 	u64 data = (addr >> 4) | map->type;
 
+	if (map->ctag)
+		data |= gp100_vmm_pte_comptagline_base(addr);
+
 	while (ptes--) {
 		VMM_WO128(pt, vmm, ptei++ * 0x10, data, 0ULL);
 		data += map->next;
@@ -440,9 +465,26 @@ gp100_vmm_valid(struct nvkm_vmm *vmm, void *argv, u32 argc,
 		return -EINVAL;
 	}
 
+	/* Handle compression. */
 	if (kindm[kind] != kind) {
-		/* Revert to non-compressed kind. */
-		kind = kindm[kind];
+		struct nvkm_device *device = vmm->mmu->subdev.device;
+
+		/* Compression is only supported when using GSP-RM, as
+		 * PMU firmware is required in order to initialise the
+		 * compbit backing store.
+		 */
+		if (nvkm_gsp_rm(device->gsp)) {
+			/* Turing GPUs require PTE_COMPTAGLINE to be filled,
+			 * in addition to specifying a compressed kind.
+			 */
+			if (device->card_type < GA100) {
+				map->ctag  = gp100_vmm_pte_comptagline_incr(1 << map->page->shift);
+				map->next |= map->ctag;
+			}
+		} else {
+			/* Revert to non-compressed kind. */
+			kind = kindm[kind];
+		}
 	}
 
 	map->type |= BIT(0);
-- 
2.51.0