linux-kernel - Re: [PATCH 1/5] usb: dwc3: exynos: Add support for SCLK present on Exynos7

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Message-ID: <CAFp+6iHLSaUjHqaKXXX0QLiRd3h+O67DRSQdExag-KUH0dnpag@mail.gmail.com>
Date:	Tue, 2 Sep 2014 16:09:08 +0530
From:	Vivek Gautam <gautam.vivek@...sung.com>
To:	Mark Rutland <mark.rutland@....com>
Cc:	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-samsung-soc@...r.kernel.org" 
	<linux-samsung-soc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"balbi@...com" <balbi@...com>, "kishon@...com" <kishon@...com>,
	"kgene.kim@...sung.com" <kgene.kim@...sung.com>
Subject: Re: [PATCH 1/5] usb: dwc3: exynos: Add support for SCLK present on Exynos7

Hi,


On Fri, Aug 29, 2014 at 12:18 AM, Mark Rutland <mark.rutland@....com> wrote:
> On Thu, Aug 28, 2014 at 09:01:56AM +0100, Vivek Gautam wrote:
>> Exynos7 also has a separate special gate clock going to the IP
>> apart from the usual AHB clock. So add support for the same.
>>
>> Signed-off-by: Vivek Gautam <gautam.vivek@...sung.com>
>> ---
>>  drivers/usb/dwc3/dwc3-exynos.c |   16 ++++++++++++++++
>>  1 file changed, 16 insertions(+)
>>
>> diff --git a/drivers/usb/dwc3/dwc3-exynos.c b/drivers/usb/dwc3/dwc3-exynos.c
>> index f9fb8ad..bab6395 100644
>> --- a/drivers/usb/dwc3/dwc3-exynos.c
>> +++ b/drivers/usb/dwc3/dwc3-exynos.c
>> @@ -35,6 +35,7 @@ struct dwc3_exynos {
>>       struct device           *dev;
>>
>>       struct clk              *clk;
>> +     struct clk              *sclk;
>>       struct regulator        *vdd33;
>>       struct regulator        *vdd10;
>>  };
>> @@ -141,10 +142,17 @@ static int dwc3_exynos_probe(struct platform_device *pdev)
>>               return -EINVAL;
>>       }
>>
>> +     /* Exynos7 has a special gate clock going to this IP */
>> +     exynos->sclk = devm_clk_get(dev, "usbdrd30_sclk");
>> +     if (IS_ERR(exynos->sclk))
>> +             dev_warn(dev, "couldn't get sclk\n");
>
> Doesn't this introduce a pointless warning for Exynos SoCs other than
> Exynos7?

True, it will introduce an unnecessary warning for non-Exynos7 systems.
I initially thought of introducing a compatible check for Exynos7-dwc3, but that
way we may end up adding such checks for future SoCs which have similar
controller but have some clock difference or some other small change, no ?

>
>> +
>>       exynos->dev     = dev;
>>       exynos->clk     = clk;
>>
>>       clk_prepare_enable(exynos->clk);
>> +     if (!IS_ERR(exynos->sclk))
>> +             clk_prepare_enable(exynos->sclk);
>
> If you replaced the returned err value with NULL you could avoid these
> IS_ERR cases.

Right, point taken.

[snip]



-- 
Best Regards
Vivek Gautam
Samsung R&D Institute, Bangalore
India
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