From: Alexandre Belloni <alexandre.belloni@bootlin.com>
To: Vladimir Zapolskiy <vz@mleia.com>
Cc: Gregory CLEMENT <gregory.clement@bootlin.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: LPC3250 periph clock at 13MHz instead of 10.4MHz
Date: Wed, 10 Apr 2019 16:18:05 +0200 [thread overview]
Message-ID: <20190410141805.GE3578@piout.net> (raw)
In-Reply-To: <20190410134443.GD3578@piout.net>
On 10/04/2019 15:44:43+0200, Alexandre Belloni wrote:
> Hi Vladimir,
>
> On 13/02/2019 19:21:44+0200, Vladimir Zapolskiy wrote:
> > > Am I missing something?
> > >
> >
> > I think I encountered quite a similar issue previously, but under another
> > circumstances, when I begin to modify HCLK PLL clock rate, can you check
> > my comment at https://lore.kernel.org/linux-clk/56D685F6.5060400@mleia.com/
> > and verify if it's about the same problem?
> >
> > Since the problem hits you also, I plan to spend some time on this weekend
> > to capture more details, fortunately there is a known workaround to pin
> > UART input clock rate to 13MHz, it might be desired to carve it in the code.
> >
>
> I'm pretty sure this is the same issue and that it doesn't only affect
> the UARTs but also timers.
>
> The 2.6.27.8 kernel code would indicated that the timers are only driven
> by sysclk, that is either 13MHz from the oscillator or 13.008896 from
> PLL397. I'm wondering how many other peripherals are affected.
>
You'll note that this is also true for the watchdog, the driver has:
// NOTE - the driver only uses this value if it can't get the clock rate from the clk_ drivers
#define WDOG_COUNTER_RATE 13000000 /*the counter clock is 13 MHz fixed */
--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-04-10 14:18 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-12 16:52 LPC3250 periph clock at 13MHz instead of 10.4MHz Alexandre Belloni
2019-02-13 17:21 ` Vladimir Zapolskiy
2019-04-10 13:44 ` Alexandre Belloni
2019-04-10 14:18 ` Alexandre Belloni [this message]
2019-04-11 9:15 ` Alexandre Belloni
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=20190410141805.GE3578@piout.net \
--to=alexandre.belloni@bootlin.com \
--cc=gregory.clement@bootlin.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=vz@mleia.com \
/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;
as well as URLs for NNTP newsgroup(s).