linux-kernel - Re: [PATCH v2] misc: atmel-ssc: Handle return value of clk_prepare_enable and clk_prepare

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Message-ID: <aa38479b-0597-17ca-ab2b-1092ece77d11@gmail.com>
Date:   Mon, 5 Jun 2017 14:53:30 +0530
From:   Arvind Yadav <arvind.yadav.cs@...il.com>
To:     Alexandre Belloni <alexandre.belloni@...e-electrons.com>
Cc:     gregkh@...uxfoundation.org, nicolas.ferre@...rochip.com,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2] misc: atmel-ssc: Handle return value of
 clk_prepare_enable and clk_prepare

Hi,

Yes, Patch v1 was wrong that's why i have push v2.
clk_prepare and clk_prepare_enable can fail. There
is not harm to check it's return value. It'll not impact present
functionality.

-arvind

On Sunday 04 June 2017 03:47 AM, Alexandre Belloni wrote:
> Hi,
>
> It is getting tiring to get patches that are nor even compile tested
> resulting from whatever static analysis tool you used.
>
> This patch has almost no value and v1 was clearly wrong.
>
> Do you realize clk_prepare and clk_prepare_enable will never fail for
> the SSC?
>
> On 02/06/2017 at 11:09:02 +0530, Arvind Yadav wrote:
>> clk_prepare_enable() and clk_prepare() can fail here and
>> we must check its return value.
>>
>> Signed-off-by: Arvind Yadav <arvind.yadav.cs@...il.com>
>> ---
>>   drivers/misc/atmel-ssc.c | 12 ++++++++++--
>>   1 file changed, 10 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/misc/atmel-ssc.c b/drivers/misc/atmel-ssc.c
>> index b2a0340..df34b81 100644
>> --- a/drivers/misc/atmel-ssc.c
>> +++ b/drivers/misc/atmel-ssc.c
>> @@ -30,6 +30,7 @@ struct ssc_device *ssc_request(unsigned int ssc_num)
>>   {
>>   	int ssc_valid = 0;
>>   	struct ssc_device *ssc;
>> +	int ret;
>>   
>>   	spin_lock(&user_lock);
>>   	list_for_each_entry(ssc, &ssc_list, list) {
>> @@ -60,7 +61,11 @@ struct ssc_device *ssc_request(unsigned int ssc_num)
>>   	ssc->user++;
>>   	spin_unlock(&user_lock);
>>   
>> -	clk_prepare(ssc->clk);
>> +	ret = clk_prepare(ssc->clk);
>> +	if (ret) {
>> +		pr_err("Failed to prepare clock\n");
>> +		return ERR_PTR(ret);
>> +	}
>>   
>>   	return ssc;
>>   }
>> @@ -195,6 +200,7 @@ static int ssc_probe(struct platform_device *pdev)
>>   	struct resource *regs;
>>   	struct ssc_device *ssc;
>>   	const struct atmel_ssc_platform_data *plat_dat;
>> +	int ret;
>>   
>>   	ssc = devm_kzalloc(&pdev->dev, sizeof(struct ssc_device), GFP_KERNEL);
>>   	if (!ssc) {
>> @@ -229,7 +235,9 @@ static int ssc_probe(struct platform_device *pdev)
>>   	}
>>   
>>   	/* disable all interrupts */
>> -	clk_prepare_enable(ssc->clk);
>> +	ret = clk_prepare_enable(ssc->clk);
>> +	if (ret)
>> +		return ret;
>>   	ssc_writel(ssc->regs, IDR, -1);
>>   	ssc_readl(ssc->regs, SR);
>>   	clk_disable_unprepare(ssc->clk);
>> -- 
>> 1.9.1
>>
>>
>> _______________________________________________
>> linux-arm-kernel mailing list
>> linux-arm-kernel@...ts.infradead.org
>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

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