Re: [PATCH v3 1/1] OMAP2: Spi: Force CS to be in inactive state after off-mode transition

[Gregory CLEMENT <gregory.clement@free-electrons.com>]

On 11/12/2010 09:37 PM, Kevin Hilman wrote:
> Gregory CLEMENT<gregory.clement@free-electrons.com>  writes:
>
>> When SPI wake up from OFF mode, CS is in the wrong state: force it to
>> the inactive state.
>>
>> During the system life, I monitored the CS behavior using a
>> oscilloscope. I also activated debug in omap2_mcspi, so I saw when
>> driver disable the clocks and
>> Each time the CS was in the correct state.
>> It was only when system was put suspend to ram with off-mode activated
>> that on resume the CS was in wrong state( ie activated).
>>
>> Signed-off-by: Gregory CLEMENT<gregory.clement@free-electrons.com>
>
> Lots of whitespace issues in this patch, please run through checkpatch.
>

Right, I forgot to use it this time.

>> ---
>>   drivers/spi/omap2_mcspi.c |   29 +++++++++++++++++++++++++++++
>>   1 files changed, 29 insertions(+), 0 deletions(-)
>>
>> diff --git a/drivers/spi/omap2_mcspi.c b/drivers/spi/omap2_mcspi.c
>> index 2a651e6..708990e 100644
>> --- a/drivers/spi/omap2_mcspi.c
>> +++ b/drivers/spi/omap2_mcspi.c
>> @@ -1305,11 +1305,40 @@ static int __exit omap2_mcspi_remove(struct
>> platform_device *pdev)
>>   /* work with hotplug and coldplug */
>>   MODULE_ALIAS("platform:omap2_mcspi");
>>   +#ifdef	CONFIG_PM
>> +/* When SPI wake up, CS is in wrong state: force it to unactive state*/
>
> This comment should be more specific that only this condition happens
> only on off-mode wakeups

OK it will be added in the next version.

>> +static int omap2_mcspi_resume(struct platform_device *pdev)
>> +{
>> +	struct spi_master	*master;
>> +	struct omap2_mcspi	*mcspi;
>> +	struct omap2_mcspi_cs *cs;
>> +
>> +	master = dev_get_drvdata(&pdev->dev);
>> +	mcspi = spi_master_get_devdata(master);
>> +	omap2_mcspi_enable_clocks(master);
>
> insert blank line here
>
>> +	/* We need to togle CS state for OMAP take this chang in account*/
>> +
>
> remove blank line here
>
>> +	list_for_each_entry(cs,&omap2_mcspi_ctx[master->bus_num - 1].cs,
>> +			    node)
>> +    {
>
> this '{' belongs on like above
>
>> +        MOD_REG_BIT(cs->chconf0, OMAP2_MCSPI_CHCONF_FORCE, 1);
>> +		__raw_writel(cs->chconf0, cs->base + OMAP2_MCSPI_CHCONF0);
>> +        MOD_REG_BIT(cs->chconf0, OMAP2_MCSPI_CHCONF_FORCE, 0);
>> +		__raw_writel(cs->chconf0, cs->base + OMAP2_MCSPI_CHCONF0);
>> +    }
>
> Rather than force the state to a hard-coded value, it seems better if
> the driver instead restore the previous state, which could be saved
> during suspend.

Well it would be surprising that driver was suspended in middle of a 
transaction (CS in active state). But it is pretty easy to get this 
information, so I will do this. It will be indeed cleaner.

>> +	omap2_mcspi_disable_clocks(master);
>> +    return 0;
>> +}
>> +#else
>> +#define	omap2_mcspi_resume	NULL
>> +#endif
>> +
>>   static struct platform_driver omap2_mcspi_driver = {
>>   	.driver = {
>>   		.name =		"omap2_mcspi",
>>   		.owner =	THIS_MODULE,
>>   	},
>> +	.resume =	omap2_mcspi_resume,
>>   	.remove =	__exit_p(omap2_mcspi_remove),
>>   };
>>   -- 1.7.0.4
>
> Kevin


-- 
Gregory Clement, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com