Panfrost impossible to probe without opp table

[Neil Armstrong]

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.

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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