[PATCH 3/9] drm: Add simplekms driver

[Maxime Ripard]

Hi Thomas,

On Fri, Sep 25, 2020 at 05:01:23PM +0200, Thomas Zimmermann wrote:
> >> +					   ARRAY_SIZE(simplekms_formats),
> >> +					   simplekms_format_modifiers,
> >> +					   connector);
> >> +	if (ret)
> >> +		return ret;
> >> +
> >> +	drm_mode_config_reset(dev);
> > 
> > This breaks fastboot. I think ideally we'd have the state represent
> > everything is on, and allocate an fb + buffer with the current contents of
> > the framebuffer. Since we can allocate an fb that matches this shouldn't
> > be a problem, just a raw memcpy_fromio should do the job.
> 
> I'm trying to wrap my head around how the fastboot setup is implemented.
> 
> Apparently, i915's fbdev code goes through the existing pipeline state
> and fills the fb_info structure with compatible settings.
> 
> Where is the initial pipeline state created? If I write reset handlers
> that initialize the pipeline to the simple-framebuffer's fixed state,
> whould that be sufficient? A later stage could then do the equivalent of
> intel_fbdev_init_bios().
> 
> The simple-kms helpers don't seem to support custom reset handlers or
> atomic-state callbacks. I guess that would require and update as well?

You probably want to read the following :)

https://lore.kernel.org/dri-devel/CAKMK7uHtqHy_oz4W7F+hmp9iqp7W5Ra8CxPvJ=9BwmvfU-O0gg@mail.gmail.com/

It's been on my todo-list since, but I never got to work on it :/

Maxime
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