Hi, Sorry for not taking a look at this sooner.
On Tue, Dec 05, 2023 at 10:48:22AM +0100, Jocelyn Falempe wrote: > drm/panic: Add a drm panic handler > > This introduces a new drm panic handler, which displays a message when a > panic occurs. > So when fbcon is disabled, you can still see a kernel panic. > > This is one of the missing feature, when disabling VT/fbcon in the kernel: > https://www.reddit.com/r/linux/comments/10eccv9/config_vtn_in_2023/ > Fbcon can be replaced by a userspace kms console, but the panic screen must > be done in the kernel. > > This is a proof of concept, and works with simpledrm and mgag200, using a new > get_scanout_buffer() api > > To test it, make sure you're using the simpledrm driver, and trigger a panic: > echo c > /proc/sysrq-trigger > > v2: > * Use get_scanout_buffer() instead of the drm client API. (Thomas Zimmermann) > * Add the panic reason to the panic message (Nerdopolis) > * Add an exclamation mark (Nerdopolis) > > v3: > * Rework the drawing functions, to write the pixels line by line and > to use the drm conversion helper to support other formats. > (Thomas Zimmermann) > > v4: > * Fully support all simpledrm formats using drm conversion helpers > * Rename dpanic_* to drm_panic_*, and have more coherent function name. > (Thomas Zimmermann) > * Use drm_fb_r1_to_32bit for fonts (Thomas Zimmermann) > * Remove the default y to DRM_PANIC config option (Thomas Zimmermann) > * Add foreground/background color config option > * Fix the bottom lines not painted if the framebuffer height > is not a multiple of the font height. > * Automatically register the driver to drm_panic, if the function > get_scanout_buffer() exists. (Thomas Zimmermann) > * Add mgag200 support. > > v5: > * Change the drawing API, use drm_fb_blit_from_r1() to draw the font. > (Thomas Zimmermann) > * Also add drm_fb_fill() to fill area with background color. > * Add draw_pixel_xy() API for drivers that can't provide a linear buffer. > * Add a flush() callback for drivers that needs to synchronize the buffer. > * Add a void *private field, so drivers can pass private data to > draw_pixel_xy() and flush(). > * Add ast support. > * Add experimental imx/ipuv3 support, to test on an ARM hw. (Maxime Ripard) > > v6: > * Fix sparse and __le32 warnings > * Drop the IMX/IPUV3 experiment, it was just to show that it works also on > ARM devices. > > With mgag200 support, I was able to test that the xrgb8888 to rgb565 > conversion is working. > > IMX/IPUV3 support is not complete, I wasn't able to have etnaviv working on > my board. I'm not sure what you mean here, etnaviv shouldn't be involved in the panic handling at all, so it's not super important that you couldn't get it to work. > But it shows that it can still work on ARM with DMA buffer in this > case. It simplifies the situation a bit, and looking at the v5 I think there's a couple of things that we need to handle / document, so it would still be very valuable. I'll review that v5 patch Maxime
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