Brian Norris
d89bd2ecd3
commit2bdba9d4a3upstream. If we disable vblank when entering self-refresh, vblank APIs (like DRM_IOCTL_WAIT_VBLANK) no longer work. But user space is not aware when we enter self-refresh, so this appears to be an API violation -- that DRM_IOCTL_WAIT_VBLANK fails with EINVAL whenever the display is idle and enters self-refresh. The downstream driver used by many of these systems never used to disable vblank for PSR, and in fact, even upstream, we didn't do that until radically redesigning the state machine in commit6c836d965b("drm/rockchip: Use the helpers for PSR"). Thus, it seems like a reasonable API fix to simply restore that behavior, and leave vblank enabled. Note that this appears to potentially unbalance the drm_crtc_vblank_{off,on}() calls in some cases, but: (a) drm_crtc_vblank_on() documents this as OK and (b) if I do the naive balancing, I find state machine issues such that we're not in sync properly; so it's easier to take advantage of (a). This issue was exposed by IGT's kms_vblank tests, and reported by KernelCI. The bug has been around a while (longer than KernelCI noticed), but was only exposed once self-refresh was bugfixed more recently, and so KernelCI could properly test it. Some other notes in: https://lore.kernel.org/dri-devel/Y6OCg9BPnJvimQLT@google.com/ Re: renesas/master bisection: igt-kms-rockchip.kms_vblank.pipe-A-wait-forked on rk3399-gru-kevin == Backporting notes: == Marking as 'Fixes' commit6c836d965b("drm/rockchip: Use the helpers for PSR"), but it probably depends on commitbed030a49f("drm/rockchip: Don't fully disable vop on self refresh") as well. We also need the previous patch ("drm/atomic: Allow vblank-enabled + self-refresh "disable""), of course. v3: * no update v2: * skip unnecessary lock/unlock Fixes:6c836d965b("drm/rockchip: Use the helpers for PSR") Cc: <stable@vger.kernel.org> Reported-by: "kernelci.org bot" <bot@kernelci.org> Link: https://lore.kernel.org/dri-devel/Y5itf0+yNIQa6fU4@sirena.org.uk/ Signed-off-by: Brian Norris <briannorris@chromium.org> Signed-off-by: Sean Paul <seanpaul@chromium.org> Link: https://patchwork.freedesktop.org/patch/msgid/20230109171809.v3.2.Ic07cba4ab9a7bd3618a9e4258b8f92ea7d10ae5a@changeid Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
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