On Fri, Jun 14, 2019 at 01:59:51PM +0800, Jian-Hong Pan wrote: > Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> 於 2019年6月13日 週四 下午6:05寫道： > > > > On Thu, Jun 13, 2019 at 04:37:48PM +0800, Jian-Hong Pan wrote: > > > Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> 於 2019年6月13日 週四 下午3:52寫道： > > > > > > > > On Mon, Jun 10, 2019 at 02:01:39PM +0800, Jian-Hong Pan wrote: > > > > > Hi, > > > > > > > > > > After apply the commit "drm/i915: Force 2*96 MHz cdclk on glk/cnl when audio > > > > > power is enabled", it induces the screen to flicker when the CDCLK changes on > > > > > the laptop like ASUS E406MA. [1] > > > > > > > > > > So, we need these commits to prevent that: > > > > > commit 48d9f87ddd21 drm/i915: Save the old CDCLK atomic state > > > > > commit 2b21dfbeee72 drm/i915: Remove redundant store of logical CDCLK state > > > > > commit 59f9e9cab3a1 drm/i915: Skip modeset for cdclk changes if possible > > > > > > > > > > [1]: https://bugzilla.kernel.org/show_bug.cgi?id=203623#c12 > > > > > > > > > > Jian-Hong Pan > > > > > > > > > > Imre Deak (2): > > > > > drm/i915: Save the old CDCLK atomic state > > > > > drm/i915: Remove redundant store of logical CDCLK state > > > > > > > > > > Ville Syrjälä (1): > > > > > drm/i915: Skip modeset for cdclk changes if possible > > > > > > > > > > drivers/gpu/drm/i915/i915_drv.h | 3 +- > > > > > drivers/gpu/drm/i915/intel_cdclk.c | 155 ++++++++++++++++++++++----- > > > > > drivers/gpu/drm/i915/intel_display.c | 48 +++++++-- > > > > > drivers/gpu/drm/i915/intel_drv.h | 18 +++- > > > > > 4 files changed, 186 insertions(+), 38 deletions(-) > > > > > > > > These are all big patches, I would like to get an ack from the i915 > > > > developer(s) that these are acceptable for the stable tree before > > > > applying them... > > > > > > > > thanks, > > > > > > > > greg k-h > > > > > > Hi Intel friends, > > > > > > We have laptops like ASUS E406MA, which hits the issue: The audio > > > playback does not work anymore after suspend & resume [1] > > > Thanks for your contribution. We found the commit "drm/i915: Force > > > 2*96 MHz cdclk on glk/cnl when audio power is enabled" can fix it. > > > But, it induces the screen to flicker when the CDCLK changes on. So, > > > we need these commits to be back ported to Linux stable 5.1.x tree to > > > prevent flickering: > > > > Pardon the delay. > > > > Now that I refreshed my memory a bit I can't really see how > > this could fix anything, except by luck. Before these patches > > we always forced cdclk to be >=2*96 MHz so audio should never > > have hit this particular problem. > > > > The reason for adding this extra complexity was to claw back > > a few milliwatts of power by allowing cdclk to drop below that > > magic limit when audio isn't needed. > > > > I *think* these patches should probably work in 5.1, but for > > now I don't see this as anything more than bandaid for an > > unknown issue somewhere else. So I'd rather like a new bug > > filed at https://bugs.freedesktop.org/enter_bug.cgi?product=DRI&component=DRM/Intel > > with a full dmesg with drm.debug=0xe (+ some audio debug > > knob(s) which show when it's trying to poke the hw during > > suspend/resume) attached. > > Thanks for your attention! > I have filed the bug on freedesktop's bugzilla. > https://bugs.freedesktop.org/show_bug.cgi?id=110916 > > I can upload more log information with guidance. OK, I think I see what's going on. We would just need to change a few lines of code to fix that (basically just s/0/2*96000/ in two places) but we don't want that upstream anymore due to these patches. So I guess we need to go ahead with the backport. I read through them and checked the 5.1 baseline and couldn't spot any problems. So for the backport to 5.1: Acked-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> -- Ville Syrjälä Intel
