linux-kernel - Re: [PATCH v2 00/11] Move PMC clocks into Tegra PMC driver

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Message-ID: <ebcce0df-bb7a-2f24-cfbc-daaf3ac6bb4f@nvidia.com>
Date:   Wed, 27 Nov 2019 13:38:27 -0800
From:   Sowjanya Komatineni <skomatineni@...dia.com>
To:     Dmitry Osipenko <digetx@...il.com>, <thierry.reding@...il.com>,
        <jonathanh@...dia.com>, <mperttunen@...dia.com>, <sboyd@...nel.org>
CC:     <gregkh@...uxfoundation.org>, <tglx@...utronix.de>,
        <robh+dt@...nel.org>, <mark.rutland@....com>,
        <allison@...utok.net>, <pdeschrijver@...dia.com>,
        <pgaikwad@...dia.com>, <mturquette@...libre.com>,
        <horms+renesas@...ge.net.au>, <Jisheng.Zhang@...aptics.com>,
        <krzk@...nel.org>, <arnd@...db.de>, <spujar@...dia.com>,
        <josephl@...dia.com>, <vidyas@...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 v2 00/11] Move PMC clocks into Tegra PMC driver


On 11/27/19 9:02 AM, Sowjanya Komatineni wrote:
>
> On 11/27/19 6:31 AM, Dmitry Osipenko wrote:
>> 27.11.2019 07:59, Sowjanya Komatineni пишет:
>>> 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 removed them from Tegra clock
>>> driver. This also adds PMC specific clock id's to use in device tree 
>>> and
>>> removed clock ids of PMC clock from Tegra clock driver.
>>>
>>> This series also includes patch to update clock provider from tegra_car
>>> to pmc in the device tree tegra210-smaug.dts that uses clk_out_2 
>>> from PMC.
>>>
>>> [v2]:    Changes between v1 and v2 are
>>>     - v2 includes patches for adding clk_out_1, clk_out_2, clk_out_3,
>>>       blink controls to Tegra PMC driver and removing clk-tegra-pmc.
>>>     - feedback related to pmc clocks in Tegra PMC driver from v1
>>>     - Removed patches for WB0 PLLM overrides and PLLE IDDQ PMC 
>>> programming
>>>       by the clock driver using helper functions from Tegra PMC.
>>>
>>>         Note:
>>>       To use helper functions from PMC driver, PMC early init need to
>>>       happen prior to using helper functions and these helper 
>>> functions are
>>>       for PLLM Override and PLLE IDDQ programming in PMC during 
>>> PLLM/PLLE
>>>       clock registration which happen in clock_init prior to Tegra PMC
>>>       probe.
>>>       Moving PLLM/PLLE clocks registration to happen after Tegra PMC
>>>       impacts other clocks EMC, MC and corresponding tegra_emc_init and
>>>       tegra_mc_init.
>>>       This implementation of configuring PMC registers thru helper
>>>       functions in clock driver needs proper changes across PMC, Clock,
>>>       EMC and MC inits to have it work across all Tegra platforms.
>>>
>>>       Currently PLLM Override is not enabled in the bootloader so 
>>> proper
>>>       patches for this fix will be taken care separately.
>> Hello Sowjanya,
>>
>> Could you please clarify what do you mean by "PLLM Override not enabled
>> in bootloader"?
>>
>> There is T124 Nyan Big Chromebook which is supported in upstream kernel,
>> it has PLLM Override set by bootloader. I also have T30 Nexus 7 tablet
>> which has the PLLM Override set by bootloader as well. It's not clear to
>> me whether this patch series is supposed to break these devices. If the
>> breakage is the case here, then I'm afraid you can't postpone supporting
>> the PLLM Override and a full-featured implementation is needed.
>
> Hi Dmitry,
>
> Secure boot currently is enabled only on Tegra210 and Tegra210 
> bootloader doesn't enable PLLM override.
>
> So PLLM override/PLLE IDDQ being in clock driver currently will not 
> break on any of existing Tegra platforms.
>
>>
>> I briefly tried to test this series on T30 and this time it doesn't hang
>> on boot, but somehow WiFi MMC card detection is broken. AFAIK, the WiFi
>> chip uses the Blink clock source and the clock should be enabled by the
>> MMC core because this is how DT part looks like:
>>
>> brcm_wifi_pwrseq: wifi-pwrseq {
>>     compatible = "mmc-pwrseq-simple";
>>     clocks = <&pmc TEGRA_PMC_CLK_BLINK>;
>>     clock-names = "ext_clock";
>>     reset-gpios =  <&gpio TEGRA_GPIO(D, 3) GPIO_ACTIVE_LOW>;
>>     post-power-on-delay-ms = <300>;
>>     power-off-delay-us = <300>;
>> };
>>
>> BTW, I  tried this series on a T20 device which also uses the Blink
>> clock for WiFi card and it works. So looks like this patchset has some
>> problem in regards to the T30 PMC clocks implementation.
>>
>> [snip]
>
> Blink init state is set to true for both Tegra20 and Tegra30 and all 
> go through the same blink programming sequence.
>
> Will try to add more debug messages to dump registers and will test 
> blink through device tree on T30 and will get back...
>
>
define value for BLINK uses BIT macro instead of just position. Will fix 
this in v3.