On 29/02/2024 12:17, Daniel Vetter wrote:
On Tue, Feb 27, 2024 at 11:04:16AM +0100, Jocelyn Falempe wrote:
Add support for the drm_panic module, which displays a user-friendly
message to the screen when a kernel panic occurs.
v8:
* Replace get_scanout_buffer() with drm_panic_set_buffer()
(Thomas Zimmermann)
Signed-off-by: Jocelyn Falempe <jfalempe@xxxxxxxxxx>
---
drivers/gpu/drm/tiny/simpledrm.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/drivers/gpu/drm/tiny/simpledrm.c b/drivers/gpu/drm/tiny/simpledrm.c
index 7ce1c4617675..a2190995354a 100644
--- a/drivers/gpu/drm/tiny/simpledrm.c
+++ b/drivers/gpu/drm/tiny/simpledrm.c
@@ -25,6 +25,7 @@
#include <drm/drm_gem_shmem_helper.h>
#include <drm/drm_managed.h>
#include <drm/drm_modeset_helper_vtables.h>
+#include <drm/drm_panic.h>
#include <drm/drm_probe_helper.h>
#define DRIVER_NAME "simpledrm"
@@ -735,6 +736,20 @@ static const struct drm_connector_funcs simpledrm_connector_funcs = {
.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
};
+static void simpledrm_init_panic_buffer(struct drm_plane *plane)
+{
+ struct simpledrm_device *sdev = simpledrm_device_of_dev(plane->dev);
+ struct drm_framebuffer fb;
+
+ /* Fake framebuffer struct for drm_panic_set_buffer */
+ fb.width = sdev->mode.hdisplay;
+ fb.height = sdev->mode.vdisplay;
+ fb.format = sdev->format;
+ fb.pitches[0] = sdev->pitch;
+
+ drm_panic_set_buffer(plane->panic_scanout, &fb, &sdev->screen_base);
+}
+
static const struct drm_mode_config_funcs simpledrm_mode_config_funcs = {
.fb_create = drm_gem_fb_create_with_dirty,
.atomic_check = drm_atomic_helper_check,
@@ -945,6 +960,8 @@ static struct simpledrm_device *simpledrm_device_create(struct drm_driver *drv,
return ERR_PTR(ret);
drm_plane_helper_add(primary_plane, &simpledrm_primary_plane_helper_funcs);
drm_plane_enable_fb_damage_clips(primary_plane);
+ drm_panic_register(primary_plane);
Just a quick comment on this:
This does not work, the driver is not ready to handle panic calls at this
stage. Instead we need to automatically register all planes that support
panic handling in drm_dev_register(), and we need to remove them all again
in drm_dev_unregister(). Outside of these functions it is not safe to call
into driver code.
If you register the primary plane and didn't call drm_panic_set_buffer()
yet, the panic handler will not do anything, so it should be safe.
But if we revert to using the get_scanout_buffer(), this makes sense.
At that point it might be simpler to only register one panic notifier per
drm_device, and push the loop into the panic handler again.
Cheers, Sima
+ simpledrm_init_panic_buffer(primary_plane);
/* CRTC */
--
2.43.0
