linux-kernel - Re: [PATCH v3 6/7] USB: ohci-at91: add usb_clk for transition to common clk framework

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Date:	Tue, 16 Jul 2013 21:06:10 +0200
From:	boris brezillon <b.brezillon@...rkiz.com>
To:	Alan Stern <stern@...land.harvard.edu>
CC:	Nicolas Ferre <nicolas.ferre@...el.com>,
	Ludovic Desroches <ludovic.desroches@...el.com>,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-usb@...r.kernel.org
Subject: Re: [PATCH v3 6/7] USB: ohci-at91: add usb_clk for transition to
 common clk framework

On 16/07/2013 20:47, Alan Stern wrote:
> On Tue, 16 Jul 2013, boris brezillon wrote:
>
>>>> +	uclk = clk_get(&pdev->dev, "usb_clk");
>>>> +	if (IS_ERR(uclk)) {
>>>> +		uclk = NULL;
>>>> +		dev_warn(&pdev->dev, "failed to get usb_clk\n");
>>>> +	}
>>> Is this really what you want for backward compatibility?
>> Here are some proposition to remove the warning message:
>>
>> 1) replace it with a dev_info and change the message:
>>       dev_info(&pdev->dev, "failed to get usb_clk (most likely using old
>> at91 clk implementation)\n");
>> 2) drop the log and silently ignore the missing clk (I'm not a big fan
>> of this solution
>>       as it may lead to some errors if we're using new clk implem and the
>> clock is really missing)
>> 3) rework the current clk_set_rate function to accept clk_set_rate on
>> usb clk and add clk_lookup entries
>>       for the usb clk (I'm not a big fan of this solution neither as this
>> modifications will only be used for a short time
>>       until the transition to common clk framework is completed).
> Another possibility is to combine this change with the clock
> implementation update, and do them in a single patch.  Then backward
> compatibility would not be an issue.
Yes, that was one of the question I asked in the cover-letter.

I think I'll move these patches in the "move to common clk" series.

Thanks
> Alan Stern
>

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