> -----Original Message----- > From: Jarkko Nikula [mailto:jarkko.nik...@linux.intel.com] > Sent: Friday, November 06, 2015 5:00 PM > To: Yu, Xiangliang; Mika Westerberg > Cc: andriy.shevche...@linux.intel.com; w...@the-dreams.de; linux- > i...@vger.kernel.org; linux-kernel@vger.kernel.org; Xue, Ken; Wan, Vincent; > Huang, Ray; Wang, Annie; Li, Tony > Subject: Re: [PATCH 1/1] I2C: designware: fix IO timeout issue for AMD > controller > > On 06.11.2015 06:34, Yu, Xiangliang wrote: > >> -----Original Message----- > >> From: Mika Westerberg [mailto:mika.westerb...@linux.intel.com] > >>> --- a/drivers/i2c/busses/i2c-designware-core.c > >>> +++ b/drivers/i2c/busses/i2c-designware-core.c > >>> @@ -783,6 +783,9 @@ irqreturn_t i2c_dw_isr(int this_irq, void > >>> *dev_id) > >>> > >>> stat = i2c_dw_read_clear_intrbits(dev); > >> > >> What if the status changes right here, before you go and mask the > interrupt? > > Have no effect, because i2c controller can't trigger next interrupt. > > > Does it mean possible lost interrupt too? I guess it can be debugged by > placing a few ms long mdelay() between clearing and masking. >
The interrupt will not be lost if status bits change before masking interrupt. > How frequent is this timeout? I guess lost interrupt is somehow nearly > related to clearing, masking and unmasking if that cycle helps. One thing that > comes to my mind is masking needed and could plain unmasking be also a > working workaround? Quite frequently. > > Have you tried to print DW_IC_INTR_STAT, DW_IC_INTR_MASK and > DW_IC_RAW_INTR_STAT when timeout occurs? E.g. just after printing the > timeout out error in i2c_dw_xfer(). Probably good in i2c_dw_isr() too if if > doesn't produce too much data and make debugging impossible. > Yes, I have tried to print these status. I have confirmed the issue with hardware engineer. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
