From: Sascha Hauer <s.hauer@pengutronix.de>
To: Teresa Gamez <T.Gamez@phytec.de>
Cc: barebox@lists.infradead.org
Subject: Re: [PATCHv2 1/2] ARM pcm043: Use PDR0 to change cpu freq
Date: Tue, 23 Aug 2011 12:43:36 +0200 [thread overview]
Message-ID: <20110823104336.GI31404@pengutronix.de> (raw)
In-Reply-To: <1314091862.3389.63.camel@lws-gamez>
On Tue, Aug 23, 2011 at 11:31:02AM +0200, Teresa Gamez wrote:
> Am Montag, den 22.08.2011, 19:27 +0200 schrieb Sascha Hauer:
> > Hi Teresa,
> >
> > On Mon, Aug 22, 2011 at 03:51:04PM +0200, Teresa Gámez wrote:
> > > Instead of changing the MPCTL to set an other cpu frequency,
> > > use the post divider.
> > >
> > > This prevents freezing when changing the clock from 399MHz to 532MHz.
> >
> > Originally this command was meant for debugging purposes. The pcm043
> > comes up with 532MHz and there should be no need to change the
> > frequency. I remember that some boards are able to run barebox with
> > 532MHz but don't manage to start the kernel with this frequency. Also I
> > have one board which does not run with 532MHz at all, but I think it's
> > an early development sample.
> > Is there a need to run boards with a lower frequency than they are able
> > to do? Otherwise, if some boards are not stable at the default 532MHz
> > I suggest we should also lower the default to 399MHz.
>
> Yes, there where different problems with older i.MX35 modules so that the
> frequency was lowered to 399MHz.
> For the revision 1315.4 we made some PCB optimizations to run the pcm043
> safe with 532MHz. Additionally we switched the silicon revision to TO 2.1.
> So it is ensured that all pcm043 with >= TO 2.1 run with 532MHz.
> For that case we made a patch (for u-boot-v2) that checks the silicon revision
> and sets up the frequency post divider accordingly.
> I'll update the patch and send it.
Thanks. This looks like a sane solution.
Sascha
>
> Teresa
>
> >
> > Sascha
> >
> > >
> > > Signed-off-by: Teresa Gámez <t.gamez@phytec.de>
> > > ---
> > > arch/arm/boards/pcm043/pcm043.c | 8 ++++----
> > > 1 files changed, 4 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/arch/arm/boards/pcm043/pcm043.c b/arch/arm/boards/pcm043/pcm043.c
> > > index 966899a..5cd6432 100644
> > > --- a/arch/arm/boards/pcm043/pcm043.c
> > > +++ b/arch/arm/boards/pcm043/pcm043.c
> > > @@ -301,8 +301,8 @@ static int pcm043_core_setup(void)
> > >
> > > core_initcall(pcm043_core_setup);
> > >
> > > -#define MPCTL_PARAM_399 (IMX_PLL_PD(0) | IMX_PLL_MFD(15) | IMX_PLL_MFI(8) | IMX_PLL_MFN(5))
> > > -#define MPCTL_PARAM_532 ((1 << 31) | IMX_PLL_PD(0) | IMX_PLL_MFD(11) | IMX_PLL_MFI(11) | IMX_PLL_MFN(1))
> > > +#define CCM_PDR0_PARAM_399 ((1 << 12) | (1 << 16))
> > > +#define CCM_PDR0_PARAM_532 (1 << 12)
> > >
> > > static int do_cpufreq(struct command *cmdtp, int argc, char *argv[])
> > > {
> > > @@ -315,10 +315,10 @@ static int do_cpufreq(struct command *cmdtp, int argc, char *argv[])
> > >
> > > switch (freq) {
> > > case 399:
> > > - writel(MPCTL_PARAM_399, IMX_CCM_BASE + CCM_MPCTL);
> > > + writel(CCM_PDR0_PARAM_399, IMX_CCM_BASE + CCM_PDR0);
> > > break;
> > > case 532:
> > > - writel(MPCTL_PARAM_532, IMX_CCM_BASE + CCM_MPCTL);
> > > + writel(CCM_PDR0_PARAM_532, IMX_CCM_BASE + CCM_PDR0);
> > > break;
> > > default:
> > > return COMMAND_ERROR_USAGE;
> > > --
> > > 1.7.0.4
> > >
> > >
> > > _______________________________________________
> > > barebox mailing list
> > > barebox@lists.infradead.org
> > > http://lists.infradead.org/mailman/listinfo/barebox
> >
>
>
>
--
Pengutronix e.K. | |
Industrial Linux Solutions | http://www.pengutronix.de/ |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
_______________________________________________
barebox mailing list
barebox@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/barebox
prev parent reply other threads:[~2011-08-23 10:43 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-22 13:51 Teresa Gámez
2011-08-22 13:51 ` [PATCHv2 2/2] ARM pcm043: change RAM timings Teresa Gámez
2011-08-22 17:27 ` [PATCHv2 1/2] ARM pcm043: Use PDR0 to change cpu freq Sascha Hauer
2011-08-23 9:31 ` Teresa Gamez
2011-08-23 10:43 ` Sascha Hauer [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20110823104336.GI31404@pengutronix.de \
--to=s.hauer@pengutronix.de \
--cc=T.Gamez@phytec.de \
--cc=barebox@lists.infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox