Re: git tree

[Thierry Reding <thierry.reding@gmail.com>]

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On Thu, Mar 05, 2015 at 07:53:16AM +0000, Zha, Qipeng wrote:
> 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

You're probably looking at the master branch, but I don't update that.
Use the for-next branch, which is what gets merged into linux-next.

Thierry

> -----Original Message-----
> From: linux-pwm-owner@vger.kernel.org [mailto:linux-pwm-owner@vger.kernel.org] On Behalf Of Shawn Guo
> Sent: Monday, March 02, 2015 8:32 PM
> To: Gaetan Hug
> Cc: thierry.reding@gmail.com; linux-pwm@vger.kernel.org; linux-kernel@vger.kernel.org; fabio.estevam@freescale.com
> 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 <shawn.guo@linaro.org>
> 
> > ---
> >  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
> > 
> --
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