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Date: Thu, 3 Feb 2011 16:30:56 -0800 From: Linus Torvalds <torvalds@...ux-foundation.org> To: Dave Airlie <airlied@...il.com> Cc: Carlos Mafra <crmafra2@...il.com>, Keith Packard <keithp@...thp.com>, Dave Airlie <airlied@...hat.com>, "Rafael J. Wysocki" <rjw@...k.pl>, Takashi Iwai <tiwai@...e.de>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Maciej Rutecki <maciej.rutecki@...il.com>, Florian Mickler <florian@...kler.org>, Andrew Morton <akpm@...ux-foundation.org>, Kernel Testers List <kernel-testers@...r.kernel.org>, Network Development <netdev@...r.kernel.org>, Linux ACPI <linux-acpi@...r.kernel.org>, Linux PM List <linux-pm@...ts.linux-foundation.org>, Linux SCSI List <linux-scsi@...r.kernel.org>, Linux Wireless List <linux-wireless@...r.kernel.org>, DRI <dri-devel@...ts.freedesktop.org> Subject: Re: 2.6.38-rc3-git1: Reported regressions 2.6.36 -> 2.6.37 On Thu, Feb 3, 2011 at 4:06 PM, Dave Airlie <airlied@...il.com> wrote: > > If we are setting a mode on a connector it automatically will end up > in a DPMS on state, > so this seemed correct from what I can see. The more I look at that function, the more I disagree with you and with that patch. The code is just crazy. First off, it isn't even necessarily setting a mode to begin with, because as far as I can tell. If the mode doesn't change, neither mode_changed nor fb_changed will be true, afaik. There seems to be a fair amount of code there explicitly to avoid changing modes if not necessary. But even _if_ we are setting a mode, if I read the code correctly, the mode may be set to NULL - which seems to mean "turn it off". In which case it looks to me that drm_helper_disable_unused_functions() will actually do a (*crtc_funcs->dpms)(crtc, DRM_MODE_DPMS_OFF); call on the crtc in question. So then blindly just saying "it's mode DRM_MODE_DPMS_ON" afterwards looks rather bogus to me. _Maybe_ it would work if it was done before that whole "disable_unused" logic. Or maybe it should just be done in drm_crtc_helper_set_mode(), which is what actually sets the mode (but there's the 'fb_changed' case too) > A future mode set shouldn't ever not turn the connector on, since > modesetting is an implicit > DPMS, > > It sounds like something more subtle than that, though I'm happy to > revert this for now, and let Keith > think about it a bit more. So I haven't heard anything from Keith. Keith? Just revert it? Or do you have a patch for people to try? Linus -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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