Re: [PATCH v5 0/8] drm: rcar-du: Add Color Management Module (CMM)

From: Eugeniu Rosca
Date: Wed May 27 2020 - 03:16:12 EST

Hi Jacopo,

On Tue, Oct 15, 2019 at 12:46:13PM +0200, Jacopo Mondi wrote:

> * Testing
> I have tested by injecting a color inversion LUT table and enabling/disabling it
> every 50 displayed frames:

Could you kindly share the cross compilation steps for your kmsxx fork?

Just out of curiosity, have you ever tried to pull the display's HDMI
cable while reading from CM2_LUT_TBL?

At least with the out-of-tree CMM implementation [*], this sends the
R-Car3 reference targets into an unrecoverable freeze, with no lockup
reported by the kernel (i.e. looks like an serious HW issue).

> CMM functionalities are retained between suspend/resume cycles (tested with
> suspend-to-idle) without requiring a re-programming of the LUT tables.

Hmm. Is this backed up by any statement in the HW User's manual?
This comes in contrast with the original Renesas CMM implementation [**]
which does make use of suspend (where the freeze actually happens).

Can we infer, based on your statement, that we could also get rid of
the suspend callback in [**]?


Best regards,
Eugeniu Rosca