linux-kernel - Re: [PATCH v5 12/44] clk: davinci: Add platform information for TI DA850 PSC

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Message-ID: <b85f7b4a-7b4c-11d8-6ea5-db4717e11658@lechnology.com>
Date:   Wed, 17 Jan 2018 11:33:09 -0600
From:   David Lechner <david@...hnology.com>
To:     Sekhar Nori <nsekhar@...com>, linux-clk@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Cc:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...eaurora.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Kevin Hilman <khilman@...nel.org>,
        Adam Ford <aford173@...il.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 12/44] clk: davinci: Add platform information for TI
 DA850 PSC

On 01/17/2018 05:57 AM, Sekhar Nori wrote:
> On Tuesday 16 January 2018 10:51 PM, David Lechner wrote:
>> On 01/16/2018 08:00 AM, Sekhar Nori wrote:
>>> On Monday 08 January 2018 07:47 AM, David Lechner wrote:
>>>> +void __init da850_psc_clk_init(void __iomem *psc0, void __iomem *psc1)
>>>> +{
>>>> +    struct clk_onecell_data *clk_data;
>>>> +
>>>> +    clk_data = davinci_psc_register_clocks(psc0, da850_psc0_info, 16);
>>>> +    if (!clk_data)
>>>> +        return;
>>>> +
>>>> +    clk_register_clkdev(clk_data->clks[3], NULL, "ti-aemif");
>>>> +    clk_register_clkdev(clk_data->clks[3], "aemif", "davinci-nand.0");
>>>> +    clk_register_clkdev(clk_data->clks[4], NULL, "spi_davinci.0");
>>>> +    clk_register_clkdev(clk_data->clks[5], NULL, "da830-mmc.0");
>>>> +    clk_register_clkdev(clk_data->clks[9], NULL, "serial8250.0");
>>>> +    clk_register_clkdev(clk_data->clks[14], "arm", NULL);
>>>> +    clk_register_clkdev(clk_data->clks[15], NULL, "davinci-rproc.0");
>>>> +
>>>> +    clk_free_onecell_data(clk_data);
>>>> +
>>>> +    clk_data = davinci_psc_register_clocks(psc1, da850_psc1_info, 32);
>>>> +    if (!clk_data)
>>>> +        return;
>>>> +
>>>> +    clk_register_clkdev(clk_data->clks[1], "usb20_psc_clk", NULL);
>>>
>>> Is this con_id really needed now? Searching for "usb20_psc_clk" in your
>>> tree results in only this one hit.
>>
>> Yes, this is left over from previous attempts.
>>
>>>
>>>> +    clk_register_clkdev(clk_data->clks[1], NULL, "musb-da8xx");
>>>> +    clk_register_clkdev(clk_data->clks[1], NULL, "cppi41-dmaengine");
>>>
>>> I guess multiple dev_id matches like these are another hurdle in moving
>>> them to davinci_psc_clk_info[] table? If its too cumbersome to keep
>>> multiple entries in the table, they can be handled as an exception at
>>> the end of processing the table? Still they are not the norm so I hope
>>> the normal case will still benefit.
>>
>> Right, as I mentioned in the reply to the previous patch, instead of
>> assigning a con_id and dev_id to each clock, we would need to assign
>> an array with a list of clocks. I think that would work better than
>> trying to handle the extras as an exception since there, on average,
>> about 5 per SoC.
> 
> Okay, are you going to try this to see how it looks? It looks like
> samsung (clk-s3c2410.c) and tegra (clk-tegra20.c) use such tables
> (although both use separate tables mapping just the gate number to
> con_id/dev_id).
> 
> Others like u8540_clk.c and clk-mmp2.c have multiple calls in code to
> clk_register_clkdev() like you have, but they keep them right after the
> gate clock registration which makes it easy to see the mapping.
> 
> clk-imx35.c has multiple clk_register_clkdev() calls, but uses an enum
> for the gates so its easy to see the mapping. This approach looks fine
> to me as well.
> 
> So looks like there is a whole gamut of ways people have approached
> this. But I do think we need to change the scheme you have currently
> since it is difficult to review and audit (believe me on this one :))
> 

OK, I'll figure out something here.