Panfrost impossible to probe without opp table

[Clément Péron]

Hi Tomeu,

On Tue, 4 Jun 2019 at 09:09, Tomeu Vizoso <tomeu.vizoso at collabora.com> wrote:
>
> 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.

Thanks,
Clément

>
> 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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