On 28/10/2025 12:51, Ryosuke Yasuoka wrote:
On Mon, Oct 27, 2025 at 02:56:21PM +0100, Jocelyn Falempe wrote:
On 23/10/2025 22:04, Ian Forbes wrote:
Sets up VRAM as the scanout buffer then switches to legacy mode.
Thank you and Ryosuke for working on drm_panic support on vmwgfx.
For the use of the drm_panic API, it looks good to me.
Acked-by: Jocelyn Falempe <[email protected]>
Suggested-by: Ryosuke Yasuoka <[email protected]>
Signed-off-by: Ian Forbes <[email protected]>
---
drivers/gpu/drm/vmwgfx/vmwgfx_kms.c | 33 ++++++++++++++++++++++++++++
drivers/gpu/drm/vmwgfx/vmwgfx_kms.h | 5 +++++
drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c | 2 ++
3 files changed, 40 insertions(+)
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
index 54ea1b513950..4ff4ae041236 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
@@ -20,6 +20,7 @@
#include <drm/drm_rect.h>
#include <drm/drm_sysfs.h>
#include <drm/drm_edid.h>
+#include <drm/drm_panic.h>
void vmw_du_init(struct vmw_display_unit *du)
{
@@ -2022,3 +2023,35 @@ bool vmw_user_object_is_null(struct vmw_user_object *uo)
{
return !uo->buffer && !uo->surface;
}
+
+int
+vmw_get_scanout_buffer(struct drm_plane *plane, struct drm_scanout_buffer *sb)
+{
+ void *vram;
+ struct vmw_private *vmw_priv = container_of(plane->dev, struct
vmw_private, drm);
+
+ // Only call on the primary display
+ if (container_of(plane, struct vmw_display_unit, primary)->unit != 0)
+ return -EINVAL;
+
+ vram = memremap(vmw_priv->vram_start, vmw_priv->vram_size,
+ MEMREMAP_WB | MEMREMAP_DEC);
+ if (!vram)
+ return -ENOMEM;
+
+ sb->map[0].vaddr = vram;
+ sb->format = drm_format_info(DRM_FORMAT_RGB565);
Let me confirm whether debugfs feature works correctly. As I mentioned
in my original patch [1], modifying this format will allow to display
the panic screen by debugfs only one time. In your environment, can you
trigger panic screen by debugfs multiple times?
The debugfs interface is broken by design, it's just here to help adding
new device support to drm_panic, so not a problem if there are garbage
after you trigger it. (it's the case on most driver anyway).
+ sb->width = vmw_priv->initial_width;
+ sb->height = vmw_priv->initial_height;
+ sb->pitch[0] = sb->width * 2;
+ return 0;
+}
+
+void vmw_panic_flush(struct drm_plane *plane)
+{
+ struct vmw_private *vmw_priv = container_of(plane->dev, struct
vmw_private, drm);
+
+ vmw_kms_write_svga(vmw_priv,
+ vmw_priv->initial_width, vmw_priv->initial_height,
+ vmw_priv->initial_width * 2, 16, 16);
vmw_kms_write_svga() calls vmw_write() which locks spin lock. Since
these functions are called in panic handler, we should avoid them. You
can find some idea in my original patch [1]!
Maybe another solution is to restrict the panic handler to
VMWGFX_PCI_ID_SVGA3, that doesn't need locks in vmw_write().
I don't know if there are still a lot of hosts with VMWGFX_PCI_ID_SVGA2
in the open, and if we want to add drm_panic support for them.
Best regards,
--
Jocelyn
[1] https://lore.kernel.org/all/[email protected]/
Thank you
Ryosuke
+}
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.h
b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.h
index 445471fe9be6..8e37561cd527 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.h
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.h
@@ -500,6 +500,11 @@ int vmw_kms_stdu_readback(struct vmw_private *dev_priv,
int vmw_du_helper_plane_update(struct vmw_du_update_plane *update);
+struct drm_scanout_buffer;
+
+int vmw_get_scanout_buffer(struct drm_plane *pl, struct drm_scanout_buffer
*sb);
+void vmw_panic_flush(struct drm_plane *plane);
+
/**
* vmw_du_translate_to_crtc - Translate a rect from framebuffer to crtc
* @state: Plane state.
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c
b/drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c
index 20aab725e53a..37cb742ba1d9 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c
@@ -1506,6 +1506,8 @@ drm_plane_helper_funcs
vmw_stdu_primary_plane_helper_funcs = {
.atomic_update = vmw_stdu_primary_plane_atomic_update,
.prepare_fb = vmw_stdu_primary_plane_prepare_fb,
.cleanup_fb = vmw_stdu_primary_plane_cleanup_fb,
+ .get_scanout_buffer = vmw_get_scanout_buffer,
+ .panic_flush = vmw_panic_flush,
};
static const struct drm_crtc_helper_funcs vmw_stdu_crtc_helper_funcs = {
