linux-kernel - Re: [PATCH 2/2] drm/panfrost: add devfreq regulator support

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Message-ID: <729d73c5-2d2d-a2b6-7715-7293744f8f95@arm.com>
Date:   Tue, 14 Apr 2020 14:09:02 +0100
From:   Robin Murphy <robin.murphy@....com>
To:     Clément Péron <peron.clem@...il.com>,
        Steven Price <steven.price@....com>
Cc:     Nishanth Menon <nm@...com>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Viresh Kumar <vireshk@...nel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        Alyssa Rosenzweig <alyssa.rosenzweig@...labora.com>
Subject: Re: [PATCH 2/2] drm/panfrost: add devfreq regulator support

On 2020-04-13 3:18 pm, Clément Péron wrote:
> Hi Steven,
> 
> On Mon, 13 Apr 2020 at 15:18, Steven Price <steven.price@....com> wrote:
>>
>> On 11/04/2020 21:06, Clément Péron wrote:
>>> OPP table can defined both frequency and voltage.
>>>
>>> Register the mali regulator if it exist.
>>>
>>> Signed-off-by: Clément Péron <peron.clem@...il.com>
>>> ---
>>>    drivers/gpu/drm/panfrost/panfrost_devfreq.c | 34 ++++++++++++++++++---
>>>    drivers/gpu/drm/panfrost/panfrost_device.h  |  1 +
>>>    2 files changed, 31 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/panfrost/panfrost_devfreq.c b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
>>> index 62541f4edd81..2dc8e2355358 100644
>>> --- a/drivers/gpu/drm/panfrost/panfrost_devfreq.c
>>> +++ b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
>>> @@ -78,12 +78,26 @@ int panfrost_devfreq_init(struct panfrost_device *pfdev)
>>>        struct device *dev = &pfdev->pdev->dev;
>>>        struct devfreq *devfreq;
>>>        struct thermal_cooling_device *cooling;
>>> +     const char *mali = "mali";
>>> +     struct opp_table *opp_table = NULL;
>>> +
>>> +     /* Regulator is optional */
>>> +     opp_table = dev_pm_opp_set_regulators(dev, &mali, 1);
>>
>> This looks like it applies before 3e1399bccf51 ("drm/panfrost: Add
>> support for multiple regulators") which is currently in drm-misc-next
>> (and linux-next). You want something more like:
> 
> Thanks for you review, indeed I didn't see that multiple regulators
> support has been added.
> Will update in v2.

Although note that we probably also want a version that can be 
backported to stable without that dependency, since this behaviour is 
arguably a regression since 221bc77914cb ("drm/panfrost: Use generic 
code for devfreq"), and does appear to have been causing subtle problems 
for users.

Robin.