linux-kernel - [PATCH v2] (drm/rockchip) Reject AFBC for resolutions >2560x1600

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Message-ID: <20250414095332.9674-1-mail@etehtsea.me>
Date: Mon, 14 Apr 2025 09:53:31 +0000
From: Konstantin Shabanov <mail@...htsea.me>
To: Sandy Huang <hjc@...k-chips.com>,
	Heiko Stübner <heiko@...ech.de>,
	Andy Yan <andy.yan@...k-chips.com>,
	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>
Cc: Konstantin Shabanov <mail@...htsea.me>,
	Daniel Stone <daniel@...ishbar.org>,
	Dan Callaghan <djc@....id.au>,
	dri-devel@...ts.freedesktop.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-rockchip@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2] (drm/rockchip) Reject AFBC for resolutions >2560x1600

As it isn't supported by hardware. At least, RK3399 doesn't support
it. From the datasheet[1]
("1.2.10 Video IN/OUT", "Display Interface", p. 17):

  Support AFBC function co-operation with GPU
    * support 2560x1600 UI

Manually tested on RockPro64 (rk3399):
- ARM_AFBC modifier is used for 1920x1080
- DRM_FORMAT_MOD_LINEAR modifier us used for 3840x2160
- No noise on the screen when sway is running in 4k
- Dynamic resolution switching works correctly in sway

Signed-off-by: Konstantin Shabanov <mail@...htsea.me>
Cc: Daniel Stone <daniel@...ishbar.org>
Reported-by: Dan Callaghan <djc@....id.au>
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/7968

[1]: https://opensource.rock-chips.com/images/d/d7/Rockchip_RK3399_Datasheet_V2.1-20200323.pdf
---
 drivers/gpu/drm/rockchip/rockchip_drm_fb.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_fb.c b/drivers/gpu/drm/rockchip/rockchip_drm_fb.c
index dcc1f07632c3..1379bc3cd937 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_fb.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_fb.c
@@ -18,6 +18,8 @@
 #include "rockchip_drm_fb.h"
 #include "rockchip_drm_gem.h"

+#define ROCKCHIP_AFBC_MAX_WIDTH		2560
+
 static const struct drm_framebuffer_funcs rockchip_drm_fb_funcs = {
 	.destroy       = drm_gem_fb_destroy,
 	.create_handle = drm_gem_fb_create_handle,
@@ -52,6 +54,13 @@ rockchip_fb_create(struct drm_device *dev, struct drm_file *file,
 	}

 	if (drm_is_afbc(mode_cmd->modifier[0])) {
+		if (mode_cmd->width > ROCKCHIP_AFBC_MAX_WIDTH) {
+			DRM_DEBUG_KMS("AFBC is not supported for the width %d (max %d)\n",
+				      mode_cmd->width,
+				      ROCKCHIP_AFBC_MAX_WIDTH);
+			return ERR_PTR(-EINVAL);
+		};
+
 		int ret, i;

 		ret = drm_gem_fb_afbc_init(dev, mode_cmd, afbc_fb);

base-commit: e7bb7d44c3b97aea1f0e354c6499900154ac67f2
--
2.48.1