Re: [PATCH v2 00/28] drm: Implement state readout support

[Maxime Ripard]

Hi,

On Thu, Apr 23, 2026 at 12:06:38PM +0200, Maxime Ripard wrote:
> Here's a series that implement what i915 calls "fastboot", ie,
> initializing the initial KMS state from the hardware state at boot, to
> skip the first modeset if the firmware already set up the display.
> 
> This series creates the infrastructure in KMS to create that state by
> relying on driver specific hooks. It also implements some infrastructure
> to check during non-blocking commits that the readout helpers work
> properly by reading out the state that was just committed and comparing
> it to what was supposed to be commited.
> 
> This relies on another set of driver hooks to compare the entities
> states, with helpers providing the default implementation.
> 
> It then implements the readout support in the TIDSS driver, and was
> tested with the SK-AM62 board. This board in particular is pretty
> interesting, since it relies on an DPI to HDMI bridge, and uses the
> drm_bridge_connector infrastructure.
> 
> So the readout works with the current state of the art on embedded-ish
> 
> It's now in a much better state than the v1 was, but there's still some
> notable things broken: 
> 
>   - Bridges do not read their input and output bus formats and flags
> 
>   - The tidss_crtc_state fields are not read properly at the moment
>     either.
> 
>   - It looks like, when left unattended, we get some atomic_flush
>     WARN eventually, maybe because of something broken around
>     hotplugging and the monitor shutting itself down?
> 
>   - If readout is disabled for any reason, the hardware isn't reset
>     anymore.
> 
> The main thing works though: the state is picked up properly, doesn't
> trigger a modeset if what was programmed is the one the first modeset
> tries to pick as well, will switch properly if it isn't, etc.

Sorry, my smtp server spuriously failed halfway through sending the
series. I just resent it.

Maxime

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