Messages in this thread | | | Subject | Re: [PATCH v3 1/3] i2c: designware: wait for disable/enable only if necessary | From | Jarkko Nikula <> | Date | Tue, 16 Aug 2016 16:59:55 +0300 |
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Hi, + Wolfram
On 07/29/2016 01:03 AM, Lucas De Marchi wrote: > From: José Roberto de Souza <jose.souza@intel.com> > > 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@intel.com> > Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com> > --- > drivers/i2c/busses/i2c-designware-core.c | 13 +++++++++---- > 1 file changed, 9 insertions(+), 4 deletions(-) > Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
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