linux-kernel - Re: [PATCH] i2c-designware: fixup of wait_for_completion

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Message-ID: <20150210075904.GC32478@opentech.at>
Date:	Tue, 10 Feb 2015 08:59:04 +0100
From:	Nicholas Mc Guire <der.herr@...r.at>
To:	Jarkko Nikula <jarkko.nikula@...ux.intel.com>
Cc:	Nicholas Mc Guire <hofrat@...dl.org>,
	Wolfram Sang <wsa@...-dreams.de>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Jisheng Zhang <jszhang@...vell.com>,
	Du Wenkai <wenkai.du@...el.com>,
	Shinya Kuribayashi <skuribay@...ox.com>,
	Romain Baeriswyl <Romain.Baeriswyl@...lis.com>,
	Andrew Jackson <Andrew.Jackson@....com>,
	David Box <david.e.box@...ux.intel.com>,
	linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] i2c-designware: fixup of wait_for_completion_timeout
	return handling

On Tue, 10 Feb 2015, Jarkko Nikula wrote:

> Hi
>
> On 02/09/2015 06:35 PM, Nicholas Mc Guire wrote:
>> return type of wait_for_completion_timeout is unsigned long not int.
>> An appropriate return variable is introduced and assignment fixed up.
>>
>> Signed-off-by: Nicholas Mc Guire <hofrat@...dl.org>
>> ---
>>
>> Patch was compile tested with x86_64_defconfig +
>> CONFIG_X86_AMD_PLATFORM_DEVICE=y, CONFIG_I2C_DESIGNWARE_PLATFORM=m
>> (implies CONFIG_I2C_DESIGNWARE_CORE=y)
>>
>> Patch is against 3.19.0-rc7 (localversion-next is -next-20150209)
>>
>>   drivers/i2c/busses/i2c-designware-core.c |    5 +++--
>>   1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
>> index 6e25c01..05934e0 100644
>> --- a/drivers/i2c/busses/i2c-designware-core.c
>> +++ b/drivers/i2c/busses/i2c-designware-core.c
>> @@ -623,6 +623,7 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
>>   {
>>   	struct dw_i2c_dev *dev = i2c_get_adapdata(adap);
>>   	int ret;
>> +	unsigned int timeout;
>>
> Not unsigned long.

oops thats braindead - yes of course unsigned long
sorry - thats a careless mistake.

>
>> @@ -656,8 +657,8 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
>>   	i2c_dw_xfer_init(dev);
>>
>>   	/* wait for tx to complete */
>> -	ret = wait_for_completion_timeout(&dev->cmd_complete, HZ);
>> -	if (ret == 0) {
>> +	timeout = wait_for_completion_timeout(&dev->cmd_complete, HZ);
>> +	if (timeout == 0) {
>>   		dev_err(dev->dev, "controller timed out\n");
>>   		/* i2c_dw_init implicitly disables the adapter */
>>   		i2c_dw_init(dev);
>>
> I'd say better to test directly with "if  
> (!wait_for_completion_timeout())" since remaining jiffies or potential  
> error code from wait_for_completion_timeout() is not used here.
>

Yup - that would eliminate the need for an additional variable
but some maintainers did not like that solution.

Thanks for your comments - Will fix it up and repost.

thx!
hofrat
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