From mboxrd@z Thu Jan 1 00:00:00 1970 From: thierry.reding@avionic-design.de (Thierry Reding) Date: Sun, 23 Sep 2012 19:22:32 +0200 Subject: PXA PWM possible regression after 3.5: backlight remains off after resume In-Reply-To: <505F28B8.1030701@yahoo.com> References: <505F28B8.1030701@yahoo.com> Message-ID: <20120923172232.GA1293@avionic-0098.mockup.avionic-design.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Sun, Sep 23, 2012 at 04:20:24PM +0100, Paul Parsons wrote: > There is a possible PXA PWM regression between 3.5 and 3.6-rc6: if I > suspend and then resume an iPAQ hx4700, the backlight remains off. > > In 3.5 the backlight would turn on after the resume. > > I presumed this is a PWM issue because the PXA PWM driver was reworked > and moved trees between 3.5 and 3.6-rc6. And there was mention of > broken PWM drivers about a month ago, for example: > http://lists.infradead.org/pipermail/linux-arm-kernel/2012-August/115717.html > > Does my backlight breakage sound familiar to anybody? Is there > anything obvious I can try before debugging it further? Looking at the code from before the move to the PWM subsystem I have a hard time understanding how this could have worked for supend/resume in the first place. The driver has never supported the supend and resume callbacks. Maybe it is also a problem related to some other change. Clocking would be a likely candidate. But again I wonder how this ever worked properly without the suspend and resume callbacks. Can you pinpoint more exactly when this failed to break. PXA PWM was already included in 3.6-rc1 so if it is related then it should have happened at that time already. Thierry -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 836 bytes Desc: not available URL: