On 8/15/2023 12:26, Hamza Mahfooz wrote:
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.pil...@amd.com>
Cc: Mario Limonciello <mario.limoncie...@amd.com>
Cc: sta...@vger.kernel.org # 6.1+

This is safe specifically because other things like FB_DAMAGE_CLIPS have come back to 6.1.y as well via f1edb2f58adb ("drm/amd/display: add FB_DAMAGE_CLIPS support") and fixups to that.

Link: https://gitlab.freedesktop.org/drm/amd/-/issues/2519
Signed-off-by: Hamza Mahfooz <hamza.mahf...@amd.com>

Reviewed-by: Mario Limonciello <mario.limoncie...@amd.com>

---
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;
+
+       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;

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