Messages in this thread | | | From | "Chew, Chiau Ee" <> | Subject | RE: [PATCH] pwm: add support for Intel Low Power Subsystem PWM | Date | Tue, 18 Feb 2014 12:05:35 +0000 |
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> -----Original Message----- > From: Mika Westerberg [mailto:mika.westerberg@linux.intel.com] > Sent: Wednesday, January 22, 2014 5:31 PM > To: Thierry Reding > Cc: One Thousand Gnomes; Chew, Chiau Ee; linux-pwm@vger.kernel.org; linux- > kernel@vger.kernel.org; Chew, Kean Ho; Chang, Rebecca Swee Fun > Subject: Re: [PATCH] pwm: add support for Intel Low Power Subsystem PWM > > On Tue, Jan 21, 2014 at 08:43:39PM +0100, Thierry Reding wrote: > > The idea behind this is that only a single user can have access to a > > given PWM device at a time. The PWM device's PWMF_REQUESTED flag is > > set (and cleared) under the pwm_lock and any subsequent users will not > > be able to use that specific device (pwm_request() return -EBUSY). > > > > There is obviously an assumption here that each user knows what they > > are doing and aren't calling any of the public pwm_*() functions > > concurrently. I haven't come across a situation where this is actually > > a problem because typically these functions are called either via > > sysfs or some other higher-level where synchronization is already > > properly handled. > > > > So the only thing that drivers should be taking care of is > > synchronizing access to registers common to multiple PWM devices. > > OK, and since LPSS PWM don't share registers we shouldn't need to do anything > here. > > > Does that clarify things? > > It does for me, thanks for the explanation.
Hi Thierry,
Would like to find out whether this pwm patch ready to get accepted into mainline kernel? Didn't mean to be pushy :). Btw, in order to have the Intel Baytrail PWM controller working, it has dependency on the acpi_lpss.c which I have sent the patch (https://lkml.org/lkml/2014/2/18/127) for upstream as well and cc you in the loop.
Thanks, Chiau Ee
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