Hi Jacopo, On Fri, Jun 05, 2020 at 03:29:00PM +0200, Jacopo Mondi wrote: > On Wed, May 27, 2020 at 09:15:55AM +0200, Eugeniu Rosca wrote: > > Could you kindly share the cross compilation steps for your kmsxx fork? > > I usually build it on the target :) Interesting approach. With ARM getting more and more potent, why not? :) > > > Just out of curiosity, have you ever tried to pull the display's HDMI > > cable while reading from CM2_LUT_TBL? > > Ahem, not really :) Did I get you right, you mean disconnecting the > HDMI cable from the board ? Right. > > > > 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 [**]? > > As Geert (thanks) explained what I've tested with is suspend-to-idle, > which retains the state of the LUT tables (and I assume other > not-yet-implemented CMM features, like CLU). I recall the out-of-tree > driver has suspend/resume routines but I never really tested that. I see. JFYI, there is a flaw in the suspend handling in the out-of-tree CMM patch [*], which renders the SoC unresponsive on HDMI hotplug. The fix is currently under review. Hopefully it will make its way to [*] in the nearest future. Just to keep in mind for the moment when CMM s2ram will become a mainline feature. > > > > [*] https://github.com/renesas-rcar/du_cmm > > [**] https://github.com/renesas-rcar/du_cmm/blob/c393ed49834bdbc/meta-rcar-gen3/recipes-kernel/linux/linux-renesas/0001-drm-rcar-du-Add-DU-CMM-support.patch#L1912 -- Best regards, Eugeniu Rosca
