Hi Jacopo, On Fri, Jun 12, 2020 at 05:00:32PM +0200, Jacopo Mondi wrote: > On Tue, Jun 09, 2020 at 04:29:59PM +0200, Eugeniu Rosca wrote: > > On Sun, Jun 07, 2020 at 05:41:58AM +0300, Laurent Pinchart wrote: > > > Note that the CMM driver is controlled by the DU driver. As the DU > > > driver will reenable the display during resume, it will call > > > rcar_du_cmm_setup() at resume time, which will reprogram the CMM. There > > > should thus be no need for manual suspend/resume handling in the CMM as > > > far as I can tell, but we need to ensure that the CMM is suspended > > > before and resumed after the DU. I believe this could be implemented > > > using device links. > > > > Based on below quote [*] from Jacopo's commit [**], isn't the device > > link relationship already in place? > > Yes, it's in place already. > > I added pm_ops to cmm just to be able to printout when suspend/resume > happens and the sequence is what comment [*] reports > > [ 222.909002] rcar_du_pm_suspend:505 > [ 223.145497] rcar_cmm_pm_suspend:193 > > [ 223.208053] rcar_cmm_pm_resume:200 > [ 223.460094] rcar_du_pm_resume:513 > > However, Laurent mentioned that in his comment here that he expects > the opposite sequence to happen (CMM to suspend before and resume after > DU). > > I still think what is implemented is correct: > - CMM is suspended after DU: when CMM is suspended, DU is not feeding > it with data > - CMM is resumed before: once DU restart operations CMM is ready to > receive data. > > Laurent, what do you think ? I think I shouldn't have written the previous e-mail in the middle of the night :-) Suspending CMM after DU is obviously correct. > > [*] Quote from commit [**] > > Enforce the probe and suspend/resume ordering of DU and CMM by > > creating a stateless device link between the two. > > > > [**] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8de707aeb45241 > > ("drm: rcar-du: kms: Initialize CMM instances") -- Regards, Laurent Pinchart _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
