Re: [PATCH 00/12] drm/panic: Split into core and helpers

[Thomas Zimmermann <tzimmermann@suse.de>]

Hi Jocelyn

Am 20.08.26 um 19:49 schrieb Jocelyn Falempe:
> On 18/08/2026 14:27, Thomas Zimmermann wrote:
>> Split DRM's current panic handling into a core and a helper module.
>> The core is still part of DRM's core library. The panic helpers are
>> part of DRM's KMS helper module (for now).
>>
>> The motivation behind this series is to get panic handling's drawing
>> code out of the DRM core. At some point it should share a single
>> module with DRM's other drawing and format conversion.
>>
>> With the series applied, panic hanlding follows DRM's established
>> design pattern of having a DRM core interface with an dedicated
>> implementation in each driver. Drivers share common code in helper
>> modules. For panic handling, the DRM core still contains the panic
>> entry points, the parameters and the debugfs interface. All drawing
>> is now located in the panic helpers.
>>
>> Patches 1 to 4 improve several issues in the current panic code. It
>> makes sense to fix them before moving the core around.
>>
>> Patches 5 to 8 put handling of all panic state and locking into a
>> single place, drm_panic_display_panic_screen(). It is maintained by
>> panic handling's DRM core code. This also enables the test cases to
>> work more independently from the kernel's configuration.
>>
>> Patches 9 to 11 split the panic-handling code into the core and panic
>> helpers. The former maintain all state, locking and public interfaces.
>> The latter handles drawing and details of the involved framebuffers.
>>
>> DRM devices that offer panic handling provide a single callback, struct
>> drm_plane_funcs.display_panic_screen. A new initializer macro makes it
>> point to the existing panic-drawing implementation. Hence there's no
>> change in features or functionality. If panic handling is configured
>> off, it all clears out to NULL.
>>
>> Patch 12 reworks the test cases slighly, so that they can be build as
>> a separate module. Do 'modprobe drm_panic_helper_test' to run them.
>>
>> Tested under bochs with debugfs and test cases.
>
> Overall the series looks good to me, and I like the split between the 
> helper and the core.
> I would just drop the first two patches, as I don't see much 
> difference between static allocation or kmalloc() at init, and I think 
> that memset() the buffers to 0 is not useful in this case.

Ok. Geert also expressed a dislike for these changes.

I have a number of changes done from the Sashiko review and will post an 
update to the series early next week.

Thanks for reviewing.

Best regards
Thomas


>
> Best regards,
>

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, (HRB 36809, AG Nürnberg)