| Message ID | 1398201501-13470-1-git-send-email-broonie@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Apr 22, 2014 at 10:18:21PM +0100, Mark Brown wrote: > From: Mark Brown <broonie@linaro.org> > > While searching for users of spi_async() I found a reference in the ad7877 > driver to using it to initiate data transfer from the interrupt handler. > However there is no code for this, instead the interrupt handler is a > threaded handler and uses spi_sync() instead. > > Remove the bitrotted comment, though in actual fact the use case mentioned > is a great use for spi_async() since it would cut down on latency handling > the interrupt by saving us a context switch before we start SPI. > > This was previously implemented, it was removed in commit b534422b2d11 > (Input: ad7877 - switch to using threaded IRQ) for code complexity reasons. > It may be better to revert that commit instead. Hmm, maybe.. although I think original would cause device 'stuck' if call to spi_async() fails, so probably not a straight revert... > > Signed-off-by: Mark Brown <broonie@linaro.org> > --- > drivers/input/touchscreen/ad7877.c | 5 ----- > 1 file changed, 5 deletions(-) > > diff --git a/drivers/input/touchscreen/ad7877.c b/drivers/input/touchscreen/ad7877.c > index 6793c85903ae..523865daa1d3 100644 > --- a/drivers/input/touchscreen/ad7877.c > +++ b/drivers/input/touchscreen/ad7877.c > @@ -210,11 +210,6 @@ static bool gpio3; > module_param(gpio3, bool, 0); > MODULE_PARM_DESC(gpio3, "If gpio3 is set to 1 AUX3 acts as GPIO3"); > > -/* > - * ad7877_read/write are only used for initial setup and for sysfs controls. > - * The main traffic is done using spi_async() in the interrupt handler. > - */ > - > static int ad7877_read(struct spi_device *spi, u16 reg) > { > struct ser_req *req; > -- > 1.9.2 > >
On Tue, Apr 22, 2014 at 05:39:28PM -0700, Dmitry Torokhov wrote: > On Tue, Apr 22, 2014 at 10:18:21PM +0100, Mark Brown wrote: > > Remove the bitrotted comment, though in actual fact the use case mentioned > > is a great use for spi_async() since it would cut down on latency handling > > the interrupt by saving us a context switch before we start SPI. > > This was previously implemented, it was removed in commit b534422b2d11 > > (Input: ad7877 - switch to using threaded IRQ) for code complexity reasons. > > It may be better to revert that commit instead. > Hmm, maybe.. although I think original would cause device 'stuck' if > call to spi_async() fails, so probably not a straight revert... Probably best just to apply this, then - someone can always reimplement if they need to.
On Wed, Apr 23, 2014 at 11:16:23AM +0100, Mark Brown wrote: > On Tue, Apr 22, 2014 at 05:39:28PM -0700, Dmitry Torokhov wrote: > > On Tue, Apr 22, 2014 at 10:18:21PM +0100, Mark Brown wrote: > > > > Remove the bitrotted comment, though in actual fact the use case mentioned > > > is a great use for spi_async() since it would cut down on latency handling > > > the interrupt by saving us a context switch before we start SPI. > > > > This was previously implemented, it was removed in commit b534422b2d11 > > > (Input: ad7877 - switch to using threaded IRQ) for code complexity reasons. > > > It may be better to revert that commit instead. > > > Hmm, maybe.. although I think original would cause device 'stuck' if > > call to spi_async() fails, so probably not a straight revert... > > Probably best just to apply this, then - someone can always reimplement > if they need to. OK, applied. Thanks.
diff --git a/drivers/input/touchscreen/ad7877.c b/drivers/input/touchscreen/ad7877.c index 6793c85903ae..523865daa1d3 100644 --- a/drivers/input/touchscreen/ad7877.c +++ b/drivers/input/touchscreen/ad7877.c @@ -210,11 +210,6 @@ static bool gpio3; module_param(gpio3, bool, 0); MODULE_PARM_DESC(gpio3, "If gpio3 is set to 1 AUX3 acts as GPIO3"); -/* - * ad7877_read/write are only used for initial setup and for sysfs controls. - * The main traffic is done using spi_async() in the interrupt handler. - */ - static int ad7877_read(struct spi_device *spi, u16 reg) { struct ser_req *req;