Re: [PATCH v2] drm/amdgpu: register a dirty framebuffer callback for fbcon

From: Hamza Mahfooz
Date: Wed Aug 16 2023 - 09:43:14 EST



On 8/16/23 01:55, Christian König wrote:


Am 15.08.23 um 19:26 schrieb Hamza Mahfooz:
fbcon requires that we implement &drm_framebuffer_funcs.dirty.
Otherwise, the framebuffer might take a while to flush (which would
manifest as noticeable lag). However, we can't enable this callback for
non-fbcon cases since it might cause too many atomic commits to be made
at once. So, implement amdgpu_dirtyfb() and only enable it for fbcon
framebuffers on devices that support atomic KMS.

Cc: Aurabindo Pillai <aurabindo.pillai@xxxxxxx>
Cc: Mario Limonciello <mario.limonciello@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # 6.1+
Link: https://gitlab.freedesktop.org/drm/amd/-/issues/2519
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@xxxxxxx>
---
v2: update variable names
---
  drivers/gpu/drm/amd/amdgpu/amdgpu_display.c | 26 ++++++++++++++++++++-
  1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
index d20dd3f852fc..d3b59f99cb7c 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
@@ -38,6 +38,8 @@
  #include <linux/pci.h>
  #include <linux/pm_runtime.h>
  #include <drm/drm_crtc_helper.h>
+#include <drm/drm_damage_helper.h>
+#include <drm/drm_drv.h>
  #include <drm/drm_edid.h>
  #include <drm/drm_fb_helper.h>
  #include <drm/drm_gem_framebuffer_helper.h>
@@ -532,11 +534,29 @@ bool amdgpu_display_ddc_probe(struct amdgpu_connector *amdgpu_connector,
      return true;
  }
+static int amdgpu_dirtyfb(struct drm_framebuffer *fb, struct drm_file *file,
+              unsigned int flags, unsigned int color,
+              struct drm_clip_rect *clips, unsigned int num_clips)
+{
+
+    if (strcmp(fb->comm, "[fbcon]"))
+        return -ENOSYS;

Once more to the v2 of this patch: Tests like those are a pretty big NO-GO for upstreaming.

On closer inspection it is actually sufficient to check if `file` is
NULL here (since it means that the request isn't from userspace). So, do
you think that would be palatable for upstream?


Regards,
Christian.

+
+    return drm_atomic_helper_dirtyfb(fb, file, flags, color, clips,
+                     num_clips);
+}
+
  static const struct drm_framebuffer_funcs amdgpu_fb_funcs = {
      .destroy = drm_gem_fb_destroy,
      .create_handle = drm_gem_fb_create_handle,
  };
+static const struct drm_framebuffer_funcs amdgpu_fb_funcs_atomic = {
+    .destroy = drm_gem_fb_destroy,
+    .create_handle = drm_gem_fb_create_handle,
+    .dirty = amdgpu_dirtyfb
+};
+
  uint32_t amdgpu_display_supported_domains(struct amdgpu_device *adev,
                        uint64_t bo_flags)
  {
@@ -1139,7 +1159,11 @@ static int amdgpu_display_gem_fb_verify_and_init(struct drm_device *dev,
      if (ret)
          goto err;
-    ret = drm_framebuffer_init(dev, &rfb->base, &amdgpu_fb_funcs);
+    if (drm_drv_uses_atomic_modeset(dev))
+        ret = drm_framebuffer_init(dev, &rfb->base,
+                       &amdgpu_fb_funcs_atomic);
+    else
+        ret = drm_framebuffer_init(dev, &rfb->base, &amdgpu_fb_funcs);
      if (ret)
          goto err;

--
Hamza