Hi Eugeniu, On Tue, Jun 09, 2020 at 04:29:59PM +0200, Eugeniu Rosca wrote: > Hi Laurent, > > 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 ? Thanks j > > [*] 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") > > -- > Best regards, > Eugeniu Rosca _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
