On 10/04/16 18:35, Laxman Dewangan wrote: > > On Sunday 10 April 2016 07:35 PM, Jonathan Cameron wrote: >> On 06/04/16 15:58, Laxman Dewangan wrote: >>> Hi Daniel, >>> >>> >>> On Wednesday 06 April 2016 07:19 PM, Daniel Baluta wrote: >>>> On Wed, Apr 6, 2016 at 1:31 PM, Laxman Dewangan <ldewangan@xxxxxxxxxx> wrote: >>>>> Some of kernel driver uses the IIO framework to get the sensor >>>>> value via ADC or IIO HW driver. The client driver get iio channel >>>>> by iio_channel_get() and release it by calling iio_channel_release(). >>>>> >>>>> Add resource managed version (devm_*) of these APIs so that if client >>>>> calls the devm_iio_channel_get() then it need not to release it explicitly, >>>>> it can be done by managed device framework when driver get un-binded. >>>>> >>>>> This reduces the code in error path and also need of .remove callback in >>>>> some cases. >>>>> >>>> Please provide at least one example of code that uses this API. >>> Most of client for this APIs are in other subsystem. >>> When I was working on the patch >>> [PATCH 2/2] thermal: generic-adc: Add ADC based thermal sensor driver >>> >>> if I have devm_iio_channel_get() then I can get .remove callback at all. >>> >>> I did not use this new APIs in my patch because they are in different subsystem. >> It's actually worse than that having taken a quick look at the generic-adc thermal patch >> you reference above. >> (perhaps worth cc'ing linux-iio for next version of that). > Sure. I will CC. > >> >> Without this devm function set you have a race in remove in which I think you can >> get attempts to access the channels after they have been released... > Yaah, possibly race for very small time possible. > > The limitation of devm_ api usage is that, we can keep using this > till we have devm_ api continuous and if some resource are not there > for devm_ then we can not use further. Possibly, I need to wait for > the devm_iio_channel_get() to merge and available for all subsystem > to use (next release) and then only I can use > devm_thermal_zone_of_sensor_register(). > The alternative would be to merge this devm_ support as a prerequisite for your thermal patches and have it go through that tree. As it's self contained I have no particular problem with that if you'd prefer to do it that way. Otherwise, you will need to do as you say above (not use devm_thermal_zone_of_sensor_register) to make sure it isn't broken in the meantime. Jonathan -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
