On Fri, 29 Jan 2016 23:26:50 -0500 "David Rivshin (Allworx)" <drivshin.allworx@xxxxxxxxx> wrote: > From: David Rivshin <drivshin@xxxxxxxxxxx> > > When using a short PWM period (approaching the min of 2/clk_rate), > pwm-omap-dmtimer does not produce accurate results. In the worst case a > requested period of 2/clk_rate would result in a real period of 4/clk_rate > instead. This is a series includes a fix for that problem, as well as > other related improvements, and is based on the current linux-pwm/for-next > tip. > > I have tested on a Sitara AM335x platform, using a scope to verify the > output with a variety of periods and duty cycles. This includes a PWM > rate up clk_rate/2 with 50% duty cycle (e.g. generating fclk/2) with > both 32768Hz and 24MHz fclks. I do not have an OMAP4 board to test with, > although appropriate sections in the the reference manuals appear > substantially the same, so I believe the changes are equally correct > there. > > Note that the OMAP4 TRMs do effectively state that the maximum PWM > rate is clk_rate/4, so at very fast PWM rates the behavior may not be > as reliable as I observed with Sitara. Although I suspect that it's > the same module and will also work, at least under some circumstances. > If anyone with OMAP4 hardware and a scope is so inclined, I would be > curious to know the results. > > David Rivshin (4): > pwm: omap-dmtimer: fix inaccurate period/duty_cycle calculation > pwm: omap-dmtimer: add sanity checking for load and match values > pwm: omap-dmtimer: round load and match values rather than truncate > pwm: omap-dmtimer: add dev_dbg() message for effective period and duty > cycle > > drivers/pwm/pwm-omap-dmtimer.c | 71 ++++++++++++++++++++++++++++++++---------- > 1 file changed, 55 insertions(+), 16 deletions(-) > Hi Thierry, Gentle ping. It does not look like you've taken this series, and I wanted to make sure you're not waiting on something from me. It would be nice to get at least the first patch into 4.5, if possible. Thanks! -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
