Hi Thierry, On 04/13/2014 03:46 PM, Shawn Guo wrote: > On Thu, Apr 10, 2014 at 05:23:49PM +0800, Liu Ying wrote: >> The i.MX pwm version2 is embedded in several i.MX SoCs, such >> as i.MX27, i.MX51 and i.MX6SL. There are four 16bit sample >> fifos in this IP, each of which determines the duty period >> of a PWM waveform in one full cycle. The IP spec mentions >> that we should not write a fourth sample because the fifo >> will become full and trigger a fifo write error(FWE) which >> will prevent the PWM from starting once it is enabled. In >> order to avoid any sample fifo overflow issue, this patch >> does software reset to clear all the sample fifos in the >> very beginning of the pwm configuration function. >> >> The fifo overflow issue can be reproduced by the following >> commands on the i.MX6SL evk platform, assuming we use pwm2 >> for the debug LED which is driven by the pin HSIC_STROBE >> and the maximal brightness is 255. >> echo 0 > /sys/class/leds/user/brightness >> echo 0 > /sys/class/leds/user/brightness >> echo 0 > /sys/class/leds/user/brightness >> echo 0 > /sys/class/leds/user/brightness >> echo 255 > /sys/class/leds/user/brightness >> Here, FWE happens(PWMSR register reads 0x58) and the LED >> can not be lighten. >> >> Cc: Sascha Hauer <[email protected]> >> Cc: Shawn Guo <[email protected]> > > Acked-by: Shawn Guo <[email protected]> > >> Cc: Lothar Waßmann <[email protected]> >> Cc: [email protected] >> Cc: [email protected] >> Signed-off-by: Liu Ying <[email protected]> >
I've got Shawn's ack on this patch. If no objections, could you take it into your PWM tree? Thanks. -- Liu Ying -- To unsubscribe from this list: send the line "unsubscribe linux-pwm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
