Am 20.08.2015 um 01:41 schrieb Krzysztof Kozlowski: > On 20.08.2015 04:36, Heiner Kallweit wrote: >> Am 19.08.2015 um 07:54 schrieb Heiner Kallweit: >>> 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 <[email protected]> >>>>> --- >>>>> 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. >> Kernel documentation says: >> "Note, if the device may execute pm_runtime calls during the probe (such as >> if it is registers with a subsystem that may call back in) then the >> pm_runtime_get_sync() call paired with a pm_runtime_put() call will be >> appropriate to ensure that the device is not put back to sleep during the >> probe. This can happen with systems such as the network device layer." >> >> I don't think this applies to SPI but I'm not expert enough to guarantee. >> At least no other SPI driver using runtime PM protects the probe function >> this way. >> Therefore I would dare to leave it as it is, especially as there don't seem >> to be any related known problems with SPI drivers. > > But you know that these runtime callbacks will be executed anyway during > probe because what I mentioned earlier - setup calls get and put. > Additionally pm_runtime_enable() is called in the middle of probe, not > at the end. This means that already it is assumed probe in certain time > can handle runtime callbacks. > > I think it is good opportunity to fix any remaining issues with runtime > PM in this driver. > > Best regards, > Krzysztof OK. Will include this and resend. Thanks for the review.
Regards, Heiner -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
