linux-kernel - [PATCH v2] drm/nouveau/kms/nve4-nv108: Don't advertise 256x256 cursor support yet

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Message-Id: <20210305222135.1269175-1-lyude@redhat.com>
Date:   Fri,  5 Mar 2021 17:21:33 -0500
From:   Lyude Paul <lyude@...hat.com>
To:     nouveau@...ts.freedesktop.org
Cc:     stable@...r.kernel.org, Ben Skeggs <bskeggs@...hat.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Dave Airlie <airlied@...hat.com>,
        Pankaj Bharadiya <pankaj.laxminarayan.bharadiya@...el.com>,
        James Jones <jajones@...dia.com>,
        dri-devel@...ts.freedesktop.org (open list:DRM DRIVER FOR NVIDIA
        GEFORCE/QUADRO GPUS), linux-kernel@...r.kernel.org (open list)
Subject: [PATCH v2] drm/nouveau/kms/nve4-nv108: Don't advertise 256x256 cursor support yet

While Kepler does technically support 256x256 cursors, it turns out that
in order for us to use these correctly we need to make sure that the cursor
plane uses a ctxdma that is set to use small (4K)/large (128K) pages -
whichever is applicable to the given cursor surface.

Right now however, we share the main kmsVramCtxDma that is used for all but
the ovly plane which defaults to small pages - resulting in artifacts when
we use 256x256 cursor surfaces. So until we teach nouveau to use a separate
ctxdma for the cursor, let's just stop advertising 256x256 cursors by
default - which should fix the issues that users were seeing.

Coincidentally - this is also why small ovlys don't work on Kepler: the
ctxdma we use for ovlys is set to large pages.

Changes since v2:
* Fix comments and patch description

Signed-off-by: Lyude Paul <lyude@...hat.com>
Fixes: d3b2f0f7921c ("drm/nouveau/kms/nv50-: Report max cursor size to userspace")
Cc: <stable@...r.kernel.org> # v5.11+
---
 drivers/gpu/drm/nouveau/dispnv50/disp.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c
index 196612addfd6..d92cf9e17ac3 100644
--- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
@@ -2693,9 +2693,19 @@ nv50_display_create(struct drm_device *dev)
 	else
 		nouveau_display(dev)->format_modifiers = disp50xx_modifiers;
 
-	if (disp->disp->object.oclass >= GK104_DISP) {
+	/* FIXME: 256x256 cursors are supported on Kepler, however unlike Maxwell and later
+	 * generations Kepler requires that we specify the page type, small (4K) or large (128K),
+	 * correctly for the ctxdma being used on curs/ovly. We currently share a ctxdma across all
+	 * display planes (except ovly) that defaults to small pages, which results in artifacting
+	 * on 256x256 cursors. Until we teach nouveau to create an appropriate ctxdma for the cursor
+	 * fb in use, simply avoid advertising support for 256x256 cursors.
+	 */
+	if (disp->disp->object.oclass >= GM107_DISP) {
 		dev->mode_config.cursor_width = 256;
 		dev->mode_config.cursor_height = 256;
+	} else if (disp->disp->object.oclass >= GK104_DISP) {
+		dev->mode_config.cursor_width = 128;
+		dev->mode_config.cursor_height = 128;
 	} else {
 		dev->mode_config.cursor_width = 64;
 		dev->mode_config.cursor_height = 64;
-- 
2.29.2