Hi, + Wolfram On 07/29/2016 01:03 AM, Lucas De Marchi wrote:
From: José Roberto de Souza <jose.souza@xxxxxxxxx> If we aren't going to continue using the controller we can just disable it instead of waiting for it to complete. The biggest improvement here is when a I2C transaction is completed and it doesn't block until the adapter is disabled. When a new transfer is needed we will disable and wait for its completion. This way the adapter will continue changing its state in parallel to the execution of the thread that requested the I2C transaction saving most of the time 25~250 usec per I2C transaction. A simple program doing a register read (1 byte write, 1 byte read) alternating on 2 different slaves repeated 25k times for each and measurements taken 4 times we get: perf stat -r4 chrt -f 10 ./i2c-test /dev/i2c-1 25000 0x40 0x6 0x1e 0x00 Before: 30.879317977 seconds time elapsed ( +- 14.83% ) After: 8.638705161 seconds time elapsed ( +- 5.90% ) Signed-off-by: José Roberto de Souza <jose.souza@xxxxxxxxx> Signed-off-by: Lucas De Marchi <lucas.demarchi@xxxxxxxxx> --- drivers/i2c/busses/i2c-designware-core.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)
Acked-by: Jarkko Nikula <jarkko.nikula@xxxxxxxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
