linux-kernel - Re: [PATCH v7 00/21] Move PMC clocks into Tegra PMC driver

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Message-ID: <dbb80785-59a8-6725-f43b-babe27ebbaeb@nvidia.com>
Date:   Thu, 9 Jan 2020 20:47:59 -0800
From:   Sowjanya Komatineni <skomatineni@...dia.com>
To:     Sameer Pujar <spujar@...dia.com>,
        Dmitry Osipenko <digetx@...il.com>, <thierry.reding@...il.com>,
        <jonathanh@...dia.com>, <broonie@...nel.org>,
        <lgirdwood@...il.com>, <perex@...ex.cz>, <tiwai@...e.com>,
        <mperttunen@...dia.com>, <gregkh@...uxfoundation.org>,
        <sboyd@...nel.org>, <robh+dt@...nel.org>, <mark.rutland@....com>
CC:     <pdeschrijver@...dia.com>, <pgaikwad@...dia.com>,
        <josephl@...dia.com>, <daniel.lezcano@...aro.org>,
        <mmaddireddy@...dia.com>, <markz@...dia.com>,
        <devicetree@...r.kernel.org>, <linux-clk@...r.kernel.org>,
        <linux-tegra@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v7 00/21] Move PMC clocks into Tegra PMC driver


On 1/9/20 8:43 PM, Sameer Pujar wrote:
> External email: Use caution opening links or attachments
>
>
> On 1/10/2020 10:06 AM, Sowjanya Komatineni wrote:
>>
>> On 1/9/20 7:32 PM, Sowjanya Komatineni wrote:
>>>
>>> On 1/9/20 7:24 PM, Sowjanya Komatineni wrote:
>>>>
>>>> On 1/9/20 5:39 PM, Sowjanya Komatineni wrote:
>>>>>
>>>>> On 1/9/20 11:44 AM, Dmitry Osipenko wrote:
>>>>>> External email: Use caution opening links or attachments
>>>>>>
>>>>>>
>>>>>> 08.01.2020 07:24, Sowjanya Komatineni пишет:
>>>>>>> This patch series moves Tegra PMC clocks from clock driver to pmc
>>>>>>> driver
>>>>>>> along with the device trees changes and audio driver which uses
>>>>>>> one of
>>>>>>> the pmc clock for audio mclk.
>>>>>>>
>>>>>>> Tegra PMC has clk_out_1, clk_out_2, clk_out_3 and blink controls
>>>>>>> which
>>>>>>> are currently registered by Tegra clock driver using
>>>>>>> clk_regiser_mux and
>>>>>>> clk_register_gate which performs direct Tegra PMC register access.
>>>>>>>
>>>>>>> When Tegra PMC is in secure mode, any access from non-secure
>>>>>>> world will
>>>>>>> not go through.
>>>>>>>
>>>>>>> This patch series adds these Tegra PMC clocks and blink controls
>>>>>>> to Tegra
>>>>>>> PMC driver with PMC as clock provider and removes them from Tegra
>>>>>>> clock
>>>>>>> driver.
>>>>>>>
>>>>>>> PMC clock clk_out_1 is dedicated for audio mclk from Tegra30 thru
>>>>>>> Tegra210
>>>>>>> and clock driver does inital parent configuration for it and
>>>>>>> enables them.
>>>>>>> But this clock should be taken care by audio driver as there is
>>>>>>> no need
>>>>>>> to have this clock pre enabled.
>>>>>>>
>>>>>>> So, this series also includes patch that updates ASoC driver to 
>>>>>>> take
>>>>>>> care of parent configuration for mclk if device tree don't specify
>>>>>>> initial parent configuration using assigned-clock-parents and
>>>>>>> controls
>>>>>>> audio mclk enable/disable during ASoC machine startup and shutdown.
>>>>>>>
>>>>>>> DTs are also updated to use clk_out_1 as audio mclk rather than
>>>>>>> extern1.
>>>>>>>
>>>>>>> This series also includes a patch for mclk fallback to extern1 when
>>>>>>> retrieving mclk fails to have this backward compatible of new DT
>>>>>>> with
>>>>>>> old kernels.
>>>>>> Suspend-resume doesn't work anymore, reverting this series helps. I
>>>>>> don't have any other information yet, please take a look.
>>>>> Thanks Dmitry. Will test suspend resume and check..
>>>>
>>>> I see if we leave audio mclk (cdev1) enabled during
>>>> tegra_asoc_utils_init, suspend resume works.
>>>>
>>>> Without audio mclk enabled during tegra_asoc_utils_init, somehow it
>>>> prevents entry to suspend on Tegra30 platform.
>>>>
>>>> Will look in detail..
>>>>
>>> audio mclk is only needed for audio and werid that having it not
>>> enabled all the time like in current clock driver prevents suspend
>>> entry on Tegra30
>>>
>>> Looks like this issue is masked earlier with having mclk enabled all
>>> the time by clock driver.
>>>
>> On linux-next without this patch series, I just disabled mclk to be
>> enabled all the time (removed set_rate from utils_init) and also
>> disabled default enable from clock driver.
>>
>> So somehow disabling mclk is preventing suspend entry.
>
> This is strange.
>
>>
>> Probably debugging suspend issue on Tegra30 when audio mclk is
>> disabled can be done separately and will keep audio mclk enabled in
>> asoc_utils_init with comment mentioning this issue and fix as TBD to
>> move on with PMC clock fixes.
>
> Sounds fine with me as the suspend/resume issue is not introduced in the
> current series. It can be addressed separately.
>
>>
Thanks Sameer. So, will keep mclk not enabled in clock driver but will 
do mclk enable in asoc_utils_init and will remove machine startup and 
shutdown.

mclk dependency with suspend/resume and I2S and audio clocks proper 
handling in audio driver can be taken care separately out of this series.

Dimitry, I hope you too agree with this.

>>
>>