linux-kernel - Re: [PATCH 7/9] fsl: add EPU FSM configuration for deep sleep

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Message-ID: <1395184882.12479.253.camel@snotra.buserror.net>
Date:	Tue, 18 Mar 2014 18:21:22 -0500
From:	Scott Wood <scottwood@...escale.com>
To:	Chenhui Zhao <chenhui.zhao@...escale.com>
CC:	<linuxppc-dev@...ts.ozlabs.org>, <linux-kernel@...r.kernel.org>,
	<leoli@...escale.com>, <Jason.Jin@...escale.com>
Subject: Re: [PATCH 7/9] fsl: add EPU FSM configuration for deep sleep

On Mon, 2014-03-17 at 18:27 +0800, Chenhui Zhao wrote:
> On Fri, Mar 14, 2014 at 05:51:09PM -0500, Scott Wood wrote:
> > On Wed, 2014-03-12 at 16:34 +0800, Chenhui Zhao wrote:
> > > On Tue, Mar 11, 2014 at 07:08:43PM -0500, Scott Wood wrote:
> > > > On Fri, 2014-03-07 at 12:58 +0800, Chenhui Zhao wrote:
> > > > > +	/* Configure the EPU Counters */
> > > > > +	epu_write(EPCCR15, 0x92840000);
> > > > > +	epu_write(EPCCR14, 0x92840000);
> > > > > +	epu_write(EPCCR12, 0x92840000);
> > > > > +	epu_write(EPCCR11, 0x92840000);
> > > > > +	epu_write(EPCCR10, 0x92840000);
> > > > > +	epu_write(EPCCR9, 0x92840000);
> > > > > +	epu_write(EPCCR8, 0x92840000);
> > > > > +	epu_write(EPCCR5, 0x92840000);
> > > > > +	epu_write(EPCCR4, 0x92840000);
> > > > > +	epu_write(EPCCR2, 0x92840000);
> > > > > +
> > > > > +	/* Configure the SCUs Inputs */
> > > > > +	epu_write(EPSMCR15, 0x76000000);
> > > > > +	epu_write(EPSMCR14, 0x00000031);
> > > > > +	epu_write(EPSMCR13, 0x00003100);
> > > > > +	epu_write(EPSMCR12, 0x7F000000);
> > > > > +	epu_write(EPSMCR11, 0x31740000);
> > > > > +	epu_write(EPSMCR10, 0x65000030);
> > > > > +	epu_write(EPSMCR9, 0x00003000);
> > > > > +	epu_write(EPSMCR8, 0x64300000);
> > > > > +	epu_write(EPSMCR7, 0x30000000);
> > > > > +	epu_write(EPSMCR6, 0x7C000000);
> > > > > +	epu_write(EPSMCR5, 0x00002E00);
> > > > > +	epu_write(EPSMCR4, 0x002F0000);
> > > > > +	epu_write(EPSMCR3, 0x2F000000);
> > > > > +	epu_write(EPSMCR2, 0x6C700000);
> > > > 
> > > > Where do these magic numbers come from?  Which chips are they valid for?
> > > 
> > > They are for T1040. Can be found in the RCPM chapter of T1040RM.
> > 
> > Then put in a comment to that effect, including what part of the RCPM
> > chapter.
> > 
> > How do you plan to handle the addition of another SoC with different
> > values?
> > 
> > -Scott
> 
> Had thought that using an array to put these values (pairs of offset and value)
> and passing the array to the function.

Arrays are better than a long sequence of function calls in any case.

> However, luckily T104x and LS1 have same values for these registers
> according to the current Reference Manuals.

If it's likely that the values will remain the same on all chips for the
near future, then a fancy mechanism to select the array to use can wait
-- but you should still use an array, and have a comment acknowledging
the possibility of needing to accommodate different values in the
future.

-Scott


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