From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: bug in PL011 console
Date: Thu, 23 Dec 2010 15:08:41 +0000 [thread overview]
Message-ID: <20101223150841.GP3636@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <20101223150234.GW14221@pengutronix.de>
On Thu, Dec 23, 2010 at 04:02:34PM +0100, Uwe Kleine-K?nig wrote:
> Steven told me on irc that sleeping was not allowed in the console write
> callback. Maybe this didn't show up earlier because not all clk
> implementations sleep as mxs' does.
>
> I think the only possible fix is to do the clk_enable in the setup
> callback instead of per-write.
>
> Will send a patch as follow up.
We really need to sort out what's expected from the CLK API. The drivers
I write assume that it's absolutely fine to call clk_enable/clk_disable
from IRQ context, and for the platforms I implemented the CLK API for,
that's absolutely true.
I'd lobby for it because it allows for proper power saving management of
clocks for devices - PL011 only enables the clock when either the port is
open or it's actually sending data out the port. So it's doing absolutely
the best power management that can be done with UARTs.
next prev parent reply other threads:[~2010-12-23 15:08 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-23 15:02 bug in PL011 console Uwe Kleine-König
2010-12-23 15:08 ` Russell King - ARM Linux [this message]
2010-12-23 15:42 ` Uwe Kleine-König
2010-12-24 5:49 ` Richard Zhao
2010-12-24 6:35 ` Jassi Brar
2010-12-24 7:10 ` Richard Zhao
2010-12-27 1:00 ` Jassi Brar
2010-12-23 15:21 ` [PATCH] serial/amba-pl011: enable uart clk in setup for console Uwe Kleine-König
2010-12-27 11:57 ` bug in PL011 console Shawn Guo
2010-12-27 20:37 ` Uwe Kleine-König
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=20101223150841.GP3636@n2100.arm.linux.org.uk \
--to=linux@arm.linux.org.uk \
--cc=linux-arm-kernel@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;
as well as URLs for NNTP newsgroup(s).