On Tue, Jun 09, 2015 at 03:29:01PM -0300, Lucas De Marchi wrote: > Hi Mika, > > On Tue, Jun 9, 2015 at 5:51 AM, Mika Westerberg > <mika.westerberg@xxxxxxxxxxxxxxx> wrote: > > On Mon, Jun 08, 2015 at 02:50:28PM -0300, lucas.de.marchi@xxxxxxxxx wrote: > >> From: Fabio Mello <fabio.mello@xxxxxxxxx> > >> > >> According to documentation and tests, initialization is not > >> necessary on module resume, since the controller keeps its state > >> between disable/enable. Change the target address is also allowed. > >> > >> So, this patch replaces the initialization on module resume with a > >> simple enable, and removes the (non required anymore) enables and > >> disables. > >> > >> Signed-off-by: Fabio Mello <fabio.mello@xxxxxxxxx> > >> Signed-off-by: Lucas De Marchi <lucas.demarchi@xxxxxxxxx> > >> --- > >> > >> These pictures explain a little more the consequence of letting the > >> enable+disable in the code: > >> > >> http://pub.politreco.com/paste/TEK0011-before.jpg > >> http://pub.politreco.com/paste/TEK0007-after.jpg > >> > >> The yellow line is a GPIO toggle in userspace to mark when we start and finish > >> the i2c transactions. The blue line is the SCL in that i2c bus. Take a look on > >> the huge pauses we have between any 2 transactions. These pauses are removed > >> with this patch and we are able to read our sensor's values in 950usec rather > >> than 5.24msec we had before. We are testing this using a Minnowboard Max that > >> has a designware i2c controller. > > > > Did you test this on any other platform than Intel Baytrail? > > No. The only soc we have here with this controller is the Baytrail. My concern is that this patch might break some non-Intel platform. It would be nice if someone (Christian?) could try this out. -- 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
