| Message ID | 20201110085041.16303-1-o.rempel@pengutronix.de |
|---|---|
| Headers | show |
| Series | Input: ads7846: reduce SPI related CPU load | expand |
On Tue, Nov 10, 2020 at 09:50:41AM +0100, Oleksij Rempel wrote: > Convert multiple full duplex transfers in to a single transfer to reduce > CPU load. > > Current driver version support following filtering modes: > - ads7846_no_filter() - not filtered > - ads7846_debounce_filter() - driver specific debounce filter > - pdata->filter - platform specific debounce filter (do any platform > provides such filter?) > > Without filter this HW is not really usable, since the physic of > resistive touchscreen can provide some bounce effects. With driver internal > filter, we have constant amount of retries + debounce retries if some anomaly > was detected. > > High amount of tiny SPI transfers is the primer reason of high CPU load > and interrupt frequency. > > This patch create one SPI transfer with all fields and not optional retires. If > bounce anomaly was detected, we will make more transfer if needed. > > Without this patch, we will get about 10% CPU load on iMX6S on pen-down event. > For example by holding stylus on the screen. > > With this patch, depending in the amount of retries, the CPU load will > be 1% with "ti,debounce-rep = <3>". > > One buffer transfer allows us to use PIO FIFO or DMA engine, depending > on the platform. > > Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de> Applied, thank you.
Hi Dmitry, On Tue, Nov 17, 2020 at 04:31:38PM -0800, Dmitry Torokhov wrote: > On Tue, Nov 10, 2020 at 09:50:41AM +0100, Oleksij Rempel wrote: > > Convert multiple full duplex transfers in to a single transfer to reduce > > CPU load. > > > > Current driver version support following filtering modes: > > - ads7846_no_filter() - not filtered > > - ads7846_debounce_filter() - driver specific debounce filter > > - pdata->filter - platform specific debounce filter (do any platform > > provides such filter?) > > > > Without filter this HW is not really usable, since the physic of > > resistive touchscreen can provide some bounce effects. With driver internal > > filter, we have constant amount of retries + debounce retries if some anomaly > > was detected. > > > > High amount of tiny SPI transfers is the primer reason of high CPU load > > and interrupt frequency. > > > > This patch create one SPI transfer with all fields and not optional retires. If > > bounce anomaly was detected, we will make more transfer if needed. > > > > Without this patch, we will get about 10% CPU load on iMX6S on pen-down event. > > For example by holding stylus on the screen. > > > > With this patch, depending in the amount of retries, the CPU load will > > be 1% with "ti,debounce-rep = <3>". > > > > One buffer transfer allows us to use PIO FIFO or DMA engine, depending > > on the platform. > > > > Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de> > > Applied, thank you. I can't find this patch in your git repository. Should I rebase it against latest git and resend it? Regards, Oleksij -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
On Wed, Jan 20, 2021 at 08:40:32AM +0100, Oleksij Rempel wrote: > > Hi Dmitry, > > On Tue, Nov 17, 2020 at 04:31:38PM -0800, Dmitry Torokhov wrote: > > On Tue, Nov 10, 2020 at 09:50:41AM +0100, Oleksij Rempel wrote: > > > Convert multiple full duplex transfers in to a single transfer to reduce > > > CPU load. > > > > > > Current driver version support following filtering modes: > > > - ads7846_no_filter() - not filtered > > > - ads7846_debounce_filter() - driver specific debounce filter > > > - pdata->filter - platform specific debounce filter (do any platform > > > provides such filter?) > > > > > > Without filter this HW is not really usable, since the physic of > > > resistive touchscreen can provide some bounce effects. With driver internal > > > filter, we have constant amount of retries + debounce retries if some anomaly > > > was detected. > > > > > > High amount of tiny SPI transfers is the primer reason of high CPU load > > > and interrupt frequency. > > > > > > This patch create one SPI transfer with all fields and not optional retires. If > > > bounce anomaly was detected, we will make more transfer if needed. > > > > > > Without this patch, we will get about 10% CPU load on iMX6S on pen-down event. > > > For example by holding stylus on the screen. > > > > > > With this patch, depending in the amount of retries, the CPU load will > > > be 1% with "ti,debounce-rep = <3>". > > > > > > One buffer transfer allows us to use PIO FIFO or DMA engine, depending > > > on the platform. > > > > > > Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de> > > > > Applied, thank you. > > I can't find this patch in your git repository. Should I rebase it > against latest git and resend it? Ugh, sorry, now applied for realz. Thanks.