Markus Pargmann 4ce78a838c can: c_can: Speed up rx_poll function ... This patch speeds up the rx_poll function by reducing the number of register reads. Replace the 32bit register read by a 16bit register read. Currently the 32bit register read is implemented by using 2 16bit reads. This is inefficient as we only use the lower 16bit in rx_poll. The for loop reads the pending interrupts in every iteration. This leads up to 16 reads of pending interrupts. The patch introduces a new outer loop to read the pending interrupts as long as 'quota' is above 0. This reduces the total number of reads. The third change is to replace the for-loop by a ffs loop. Tested on AM335x. I removed all 'static' and 'inline' from c_can.c to see the timings for all functions. I used the function tracer with trace_stats. 125kbit: Function Hit Time Avg s^2 -------- --- ---- --- --- c_can_do_rx_poll 63960 10168178 us 158.977 us 1493056 us With patch: c_can_do_rx_poll 63941 3764057 us 58.867 us 776162.2 us 1Mbit: Function Hit Time Avg s^2 -------- --- ---- --- --- c_can_do_rx_poll 69489 30049498 us 432.435 us 9271851 us With patch: c_can_do_rx_poll 207109 24322185 us 117.436 us 171469047 us Signed-off-by: Markus Pargmann <mpa@pengutronix.de> Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>		2013-12-17 11:47:19 +01:00
..
c_can_pci.c	can: c_can: remove unnecessary pci_set_drvdata()	2013-09-21 15:43:15 +02:00
c_can_platform.c	net: can: c_can_platform: Remove redundant of_match_ptr	2013-10-01 12:30:25 -04:00
c_can.c	can: c_can: Speed up rx_poll function	2013-12-17 11:47:19 +01:00
c_can.h	can: c_can: Add d_can raminit support	2012-11-27 09:49:31 +01:00
Kconfig	can: Kconfig: convert 'depends on CAN_DEV' into 'if CAN_DEV...endif' block	2013-01-26 16:58:58 +01:00
Makefile	c_can_pci: generic module for C_CAN/D_CAN on PCI	2012-06-19 21:22:28 +02:00