Re: [RFC] Pre-Memory Sign-of-Life using Intel uGOP

+ Subrata

On Tue, 22 Aug 2023 at 15:35, Nico Huber <[email protected]> wrote:

> Hi Jeremy,
>
> On 14.08.23 22:52, Compostella, Jeremy wrote:
> > We propose to take advantage of a proprietary driver Intel already
> supports, validates and includes in FSP silicon: the Intel Graphics PEIM
> (Pre-EFI Initialization Module) driver also known as the GOP (Graphical
> Output Protocol) driver.
>
> just to make sure nobody makes wrong assumptions: Will the uGOP be
> open-source or proprietary as well? I first thought the latter. But
> your proposed code-flow looks like some sort of dynamic linking with
> coreboot.
>
> > We intend to keep providing such a binary base solution on the long run
> as it addresses our software convergence goals and is compatible with early
> platform development stage constraints. [libgfxinit] supports can always be
> added later by the open-source community once the Graphics Programmer
> Reference Manuals are published.
>
> Sad to hear about this decision. It seems Intel is forgetting about
> non-consumer products (e.g. embedded market) where the code isn't
> needed years ahead of a platform launch.
>
> > We also noticed that microGOP is faster to bring-up graphics than
> libgfxinit. Indeed, according to previously captured numbers on Raptor Lake
> compared to some number of microGOP on Meteor Lake, microGOP is three times
> faster to bring up graphics than libgfxinit on an eDP panel (119 ms vs 373
> ms).
>
> Configuring the hardware and bringing up the eDP link should take
> about 20~30ms mostly depending on how long it takes to read the
> EDID. The longer delays are likely about panel power sequencing.
> IIRC, libgfxinit falls back to hardcoded default values if the
> sequencer is unconfigured, while the GOP just leaves it like that.
> Chromebooks often skip the configuration[1] in firmware and leave
> it to the OS driver. Using wrong delays probably doesn't hurt on
> a rare interactive boot. However, I guess doing this on regular
> boots might not be the best idea.
>
> Nico
>
> [1] https://doc.coreboot.org/gfx/display-panel.html
>
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