Panfrost impossible to probe without opp table

[Tomeu Vizoso]

On Mon, 3 Jun 2019 at 19:24, Clément Péron <peron.clem at gmail.com> wrote:
>
> Hi,
>
>
> On Fri, 31 May 2019 at 14:13, Neil Armstrong <narmstrong at baylibre.com> wrote:
> >
> > On 31/05/2019 14:09, Tomeu Vizoso wrote:
> > > On Fri, 31 May 2019 at 14:03, Neil Armstrong <narmstrong at baylibre.com> wrote:
> > >>
> > >> Hi Tomeu,
> > >>
> > >> On 31/05/2019 13:59, Tomeu Vizoso wrote:
> > >>> On Wed, 29 May 2019 at 23:29, Clément Péron <peron.clem at gmail.com> wrote:
> > >>>>
> > >>>> Hi,
> > >>>>
> > >>>> I have rebase my kernel on latest 5.2-rc2, and my panfrost driver is
> > >>>> no more probing.
> > >>>>
> > >>>> The issue is coming from f3617b449d0bcf3b5d80a97f51498dcf7463cf7e
> > >>>>     drm/panfrost: Select devfreq
> > >>>>
> > >>>>     Currently, there is some logic for the driver to work without devfreq.
> > >>>>     However, the driver actually fails to probe if !CONFIG_PM_DEVFREQ.
> > >>>>
> > >>>>     Fix this by selecting devfreq, and drop the additional checks
> > >>>>     for devfreq.
> > >>>>
> > >>>> It seems that with this commit the OPP table is now mandatory.
> > >>>> is it intentional?
> > >>>
> > >>> Hi Clément,
> > >>>
> > >>> devfreq support is intentionally required. I got a H64 board which I'm
> > >>> using to add T720 support to Panfrost.
> > >>
> > >> operating-points-v2 and clocks are optional, devfreq should be optional,
> > >> this was the default behaviour of the first applied version.
> > >
> > > I'm concerned by the safety of running these GPUs all the time at
> > > their maximum frequencies. Maybe not on Chromebooks and other consumer
> > > devices, but the SBCs I have here have all very crappy heat
> > > dissipation.
> >
> > Sure, it's logical to have devfreq running on these devices.
> >
> > >
> > >> Amlogic dt does not have operating-points-v2, and devfreq won't be supported
> > >> soon.
> > >
> > > What's the problem with coming up with the operating points?
> >
> > Because the bindings are optional :
> > Optional properties:
> >
> > - clocks : Phandle to clock for the Mali Midgard device.
> >
> > - mali-supply : Phandle to regulator for the Mali device. Refer to
> >   Documentation/devicetree/bindings/regulator/regulator.txt for details.
> >
> > - operating-points-v2 : Refer to Documentation/devicetree/bindings/opp/opp.txt
> >   for details.
> >
> > Unless you change the bindings, it's mandated to be optional by the bindings.
>
> I can propose a patch to fix this but what is the best solution?
>
> Leave DEVFREQ config mandatory but allow to probe without opp_table?
> Revert the commit?
> Fix the documentation to have opp table mandatory?

Hi Clément,

Neil has a patch on its way to keep DEVFREQ compulsory at build time,
but have it disabled at runtime if we don't have a OPP table.

Cheers,

Tomeu

> Thanks,
> Clément
>
> >
> > Neil
> >
> >
> > >
> > > Thanks,
> > >
> > > Tomeu
> > >
> > >> Neil
> > >>
> > >>>
> > >>> Once I'm able to test the GPU properly along with frequency scaling, I
> > >>> will ping you so you can retest and resubmit.
> > >>>
> > >>> Thanks,
> > >>>
> > >>> Tomeu
> > >>>
> > >>>> Actually
> > >>>> [    3.046237] panfrost 1800000.gpu: clock rate = 432000000
> > >>>> [    3.051593] panfrost 1800000.gpu: bus_clock rate = 100000000
> > >>>> [    3.096012] panfrost 1800000.gpu: mali-t720 id 0x720 major 0x1
> > >>>> minor 0x1 status 0x0
> > >>>> [    3.103682] panfrost 1800000.gpu: features: 00000000,10309e40,
> > >>>> issues: 00000000,21054400
> > >>>> [    3.111789] panfrost 1800000.gpu: Features: L2:0x07110206
> > >>>> Shader:0x00000000 Tiler:0x00000809 Mem:0x1 MMU:0x00002821 AS:0xf
> > >>>> JS:0x7
> > >>>> [    3.123435] panfrost 1800000.gpu: shader_present=0x3 l2_present=0x1
> > >>>> [    3.130405] panfrost 1800000.gpu: Fatal error during devfreq init
> > >>>>
> > >>>> With commit reverted
> > >>>> [    3.038236] panfrost 1800000.gpu: clock rate = 432000000
> > >>>> [    3.043593] panfrost 1800000.gpu: bus_clock rate = 100000000
> > >>>> [    3.087994] panfrost 1800000.gpu: mali-t720 id 0x720 major 0x1
> > >>>> minor 0x1 status 0x0
> > >>>> [    3.095658] panfrost 1800000.gpu: features: 00000000,10309e40,
> > >>>> issues: 00000000,21054400
> > >>>> [    3.103763] panfrost 1800000.gpu: Features: L2:0x07110206
> > >>>> Shader:0x00000000 Tiler:0x00000809 Mem:0x1 MMU:0x00002821 AS:0xf
> > >>>> JS:0x7
> > >>>> [    3.115410] panfrost 1800000.gpu: shader_present=0x3 l2_present=0x1
> > >>>> [    3.122798] [drm] Initialized panfrost 1.0.0 20180908 for
> > >>>> 1800000.gpu on minor 0
> > >>>>
> > >>>>
> > >>>> Thanks,
> > >>>> Clément
> > >>>>
> > >>>> _______________________________________________
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> > >>>
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