This patch series enables ADC to be clocked at 24MHz as the TI AM335x ADC driver has already adopted to use DMA to transfer ADC samples. Now ADC can generated upto 800K Samples per second with the patch [1] on AM335x BBB and AM437x GP EVM. when ADC ref clock is set at 24MHz, I am seeing some issue with touch screen pointer as the pointer jumps to random locations with free draw application. The issue is due to increase in ADC clock and charge delay for the touchscreen ADC line duration reduced. So the notation of ti,charge-delay in terms of ADC clock is wrong, it has to be represented in time and driver has to convert the charge delay time to ADC clocks based on what ADC clock frequency is set. Measured the performance with the iio_generic_buffer with the patch [2] applied Verified the touch screen on AM335x GP EVM and AM335x BBB LCD7 cape with [3] dts for display and touch screen to work. Changes from initial version: * Removed modification to STEPCONFIG_OPENDLY defined as it doesn't affect/improve touchscreen performance. * Changed ti,charge-delay to ti,charge-delay-ns [1] - http://pastebin.ubuntu.com/23357935/ [2] - http://pastebin.ubuntu.com/23357939/ [3] - http://pastebin.ubuntu.com/23456616/ Mugunthan V N (3): dt/binding: ti-tsc-adc: deprecate ti,charge-delay and add binding doc for ti,charge-delay-ns Input: ti_am335x_tsc: Add support for ti,charge-delay-ns drivers: mfd: ti_am335x_tscadc: increase ADC ref clock to 24MHz .../bindings/input/touchscreen/ti-tsc-adc.txt | 32 ++++++++++++++-------- drivers/input/touchscreen/ti_am335x_tsc.c | 31 +++++++++++++++------ include/linux/mfd/ti_am335x_tscadc.h | 2 +- 3 files changed, 45 insertions(+), 20 deletions(-) -- 2.11.0.rc0.7.gbe5a750 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
