mainline kernel: cpufreq for bcm2835

[Stefan Wahren]

Hi Peter,

> Peter Robinson <pbrobinson at gmail.com> hat am 2. April 2018 um 18:21 geschrieben:
> 
> 
> On Mon, Apr 2, 2018 at 5:09 PM, Stefan Wahren <stefan.wahren at i2se.com> wrote:
> > Hi Sergey,
> >
> > [add linux-rpi-kernel]
> >
> >> Sergey Suloev <ssuloev at orpaltech.com> hat am 2. April 2018 um 17:45 geschrieben:
> >>
> >>
> >> Hi Stefan
> >>
> >> can any give any hint about the status of bcn2835 cpufreq in mainline
> >> kernel ?
> >
> > in short: currently no support yet
> >
> >>
> >> Are you (or anyone else) working on it ?
> >
> > No, this not on my TODO list [1].
> >
> > Current prio:
> > - Raspberry Pi 3+
> > - fixes and improvements for Raspberry Pi 3 DT
> > - VCHIQ data corruption
> >
> > Implementing/Porting the cpufreq driver is only half of the work. Also all drivers which depend on the VPU core clock should be able to handle a frequency change (sdhost, i2c, aux uart comes to my mind). But i will be happy if somebody takes care of it.
> >
> > Is this a critical feature for you?
> 
> It's probably one of the most complained about things I get on Fedora
> along side the touch screen and camera.

at least for the touch screen there is a panel driver and a DT snippet (Eric prefer an overlay).

Since the camera requires VCHIQ the corruption should be fixed before. 

> It's on my list to try and get
> working but I've not had huge luck. The downstream driver builds, but
> complains about being unable to find the firmware when I load it as a
> module.

one issue with the downstream driver is the lack of DT operating points [1],
but this is not related to your issue.

Stefan

[1] - https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/Documentation/devicetree/bindings/opp/opp.txt?h=next-20180329

> The firmware interface is built in (it has to be for things
> like usb power) so by the time userspace is running in level 3 I would
> have though the firmware interface would be available, I've not had
> time to debug it further than that. Can provide more details later in
> the week if it's helpful.
> 
> Peter