linux-kernel - Re: [PATCH v5 11/44] clk: davinci: Add platform information for TI DA830 PSC

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Date:   Thu, 18 Jan 2018 13:23:08 +0530
From:   Sekhar Nori <nsekhar@...com>
To:     David Lechner <david@...hnology.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 11/44] clk: davinci: Add platform information for TI
 DA830 PSC

On Wednesday 17 January 2018 11:02 PM, David Lechner wrote:
>>>>> +    clk_register_clkdev(clk_data->clks[3], "gpio", NULL);
>>>>
>>>> This is pretty bad (and no fault of yours) - having a con_id but no
>>>> device name. Can you please make a pre-series which passes NULL con_id
>>>> in gpio-davinci.c?
>>>
>>> I'll give it a try. This is complicated by the fact that the con_id has
>>> made it's way into the device tree bindings. However, I think we can
>>> safely deprecate clock-names = "gpio" in the device tree bindings since
>>> we can make the driver ignore that property to preserve backwards
>>> compatibility.
> 
> Agreed.
> 
>> I don't think this breaks DT-backward compatibility. Passing a NULL
>> con_id in driver should find the clock for that device even if DT entry
>> has clock-names present. As far as I can read clk_find().
>>
>> The less intrusive alternate is to add the GPIO device name in the table
>> here, while keeping the con_id and keeping the driver untouched. The
>> advantage of that is lesser number of dependent patches for this series
>> to go in.
>>
>> Later once CCF conversion has been there in the kernel for one full
>> release and no regressions, these other clean-ups can be done.
> 
> I like this approach.

One downside is that we will have to have clock-names = "gpio" in da850
device-tree too. Since its already present in keystone already, I don't
think adding one more is such a big issue.

Thanks,
Sekhar