Re: [PATCH 2/3] spi: s3c64xx: fix runtime PM handling

[Heiner Kallweit <hkallweit1-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

Am 19.08.2015 um 02:35 schrieb Krzysztof Kozlowski:
> On 19.08.2015 06:06, Heiner Kallweit wrote:
>> The patch fixes / extends the runtime PM handling.
>> - Currently the driver instructs the SPI core to use auto-suspend
>>   but doesn't configure it. Add the necessary calls and let it
>>   autosuspend after probe.
> 
> After quick look at the driver I think it does not use autosuspend
> fully. It just sets master->auto_runtime_pm (so the core code will use
> autosuspend) but its own calls to pm_runtime_put() are regular ones.
> Shouldn't this be enhanced as well?
Right, the pm_runtime_put calls in s3c64xx_spi_setup should be
replaced as well. Will provide an updated patch.
> 
>> - In case the driver registration fails runtime PM needs to be
>>   properly disabled.
>>
>> Signed-off-by: Heiner Kallweit <hkallweit1-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>> ---
>>  drivers/spi/spi-s3c64xx.c | 11 ++++++++++-
>>  1 file changed, 10 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
>> index c4d3b06..15a6de1 100644
>> --- a/drivers/spi/spi-s3c64xx.c
>> +++ b/drivers/spi/spi-s3c64xx.c
>> @@ -32,6 +32,7 @@
>>  #define MAX_SPI_PORTS		6
>>  #define S3C64XX_SPI_QUIRK_POLL		(1 << 0)
>>  #define S3C64XX_SPI_QUIRK_CS_AUTO	(1 << 1)
>> +#define AUTOSUSPEND_TIMEOUT     2000
>>  
>>  /* Registers and bit-fields */
>>  
>> @@ -1180,13 +1181,15 @@ static int s3c64xx_spi_probe(struct platform_device *pdev)
>>  	       S3C64XX_SPI_INT_TX_OVERRUN_EN | S3C64XX_SPI_INT_TX_UNDERRUN_EN,
>>  	       sdd->regs + S3C64XX_SPI_INT_EN);
>>  
>> +	pm_runtime_set_autosuspend_delay(dev, AUTOSUSPEND_TIMEOUT);
>> +	pm_runtime_use_autosuspend(dev);
>>  	pm_runtime_set_active(dev);
>>  	pm_runtime_enable(dev);
>>  
>>  	ret = devm_spi_register_master(dev, master);
>>  	if (ret != 0) {
>>  		dev_err(dev, "cannot register SPI master: %d\n", ret);
>> -		goto err3;
>> +		goto err4;
>>  	}
>>  
>>  	dev_dbg(dev, "Samsung SoC SPI Driver loaded for Bus SPI-%d with %d Slaves attached\n",
>> @@ -1195,8 +1198,14 @@ static int s3c64xx_spi_probe(struct platform_device *pdev)
>>  					mem_res, (FIFO_LVL_MASK(sdd) >> 1) + 1,
>>  					sdd->rx_dma.dmach, sdd->tx_dma.dmach);
>>  
>> +	pm_runtime_mark_last_busy(dev);
>> +	pm_runtime_autosuspend(dev);
> 
> There is a high chance that device will be suspended already at this
> point because pm_runtime_put() in setup. In most cases (when SPI is
> started) this won't do anything so we are back at first of my questions
> - shouldn't you update pm_runtime_put() calls?
Yes, these calls should be updated.
> 
> Additionally (which is not related to your patch) shouldn't we
> pm_runtime_get() at some point in probe() to be sure that it won't be
> suspended to early?
Not 100% sure at this moment, I will check.
> 
>> +
>>  	return 0;
>>  
>> +err4:
>> +	pm_runtime_disable(dev);
>> +	pm_runtime_set_suspended(dev);
> 
> Please separate fixes from enhancements into different patches.
OK, will do so.
> 
> Best regards,
> Krzysztof
> 
>>  err3:
>>  	clk_disable_unprepare(sdd->src_clk);
>>  err2:
>>
> 
> 

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