Re: Panfrost impossible to probe without opp table

[Tomeu Vizoso <tomeu.vizoso@collabora.com>]

On Fri, 31 May 2019 at 14:03, Neil Armstrong <narmstrong@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@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.

> 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?

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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