Hi I got pwm subsystem git tree info as below from v3.19-rc6 MAINTAINER And I clone it, found the version is v3.12 Is the tree current maintain tree ? or there is a new one, thanks.
git git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm.git Best wishes Qipeng -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Shawn Guo Sent: Monday, March 02, 2015 8:32 PM To: Gaetan Hug Cc: [email protected]; [email protected]; [email protected]; [email protected] Subject: Re: [PATCH] pwm: mxs: fix period divider computation On Wed, Feb 18, 2015 at 02:06:34PM +0100, Gaetan Hug wrote: > The driver computes which clock divider it sould be using from the > requested period. This computation assumes that the link between the > register value and the actual divider value is raising 2 to the power > of the registry value. > > div = 1 << regvalue > > This is true only for the first 5 values out of 8. Next values are 64, > 256 and, 1024 - instead of 32, 64, 128. Just checked i.MX28 Reference Manual, and yes, this is the case. > This affects only the users requesting a period > 0.04369s. > > Replace the computation with a look-up table. Your SoB is missing here. Otherwise, Acked-by: Shawn Guo <[email protected]> > --- > drivers/pwm/pwm-mxs.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/drivers/pwm/pwm-mxs.c b/drivers/pwm/pwm-mxs.c index > f75ecb0..c65e183 100644 > --- a/drivers/pwm/pwm-mxs.c > +++ b/drivers/pwm/pwm-mxs.c > @@ -35,6 +35,8 @@ > #define PERIOD_CDIV(div) (((div) & 0x7) << 20) > #define PERIOD_CDIV_MAX 8 > > +static unsigned const int cdiv[PERIOD_CDIV_MAX] = {1, 2, 4, 8, 16, > +64, 256, 1024}; > + > struct mxs_pwm_chip { > struct pwm_chip chip; > struct clk *clk; > @@ -54,13 +56,13 @@ static int mxs_pwm_config(struct pwm_chip *chip, > struct pwm_device *pwm, > > rate = clk_get_rate(mxs->clk); > while (1) { > - c = rate / (1 << div); > + c = rate / cdiv[div]; > c = c * period_ns; > do_div(c, 1000000000); > if (c < PERIOD_PERIOD_MAX) > break; > div++; > - if (div > PERIOD_CDIV_MAX) > + if (div >= PERIOD_CDIV_MAX) > return -EINVAL; > } > > -- > 1.7.10.4 > -- 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 -- 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
