linux-kernel - Re: [PATCH v2 2/3] fbcon: use the cursor blink interval provided by vt

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Message-ID: <20150520123615.GA24016@ulmo.nvidia.com>
Date:	Wed, 20 May 2015 14:36:17 +0200
From:	Thierry Reding <thierry.reding@...il.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	Kevin Hilman <khilman@...nel.org>,
	Scot Doyle <lkml14@...tdoyle.com>,
	Tomi Valkeinen <tomi.valkeinen@...com>,
	Michael Kerrisk <mtk.manpages@...il.com>,
	Jiri Slaby <jslaby@...e.cz>,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	Pavel Machek <pavel@....cz>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	lkml <linux-kernel@...r.kernel.org>, linux-fbdev@...r.kernel.org,
	linux-man@...r.kernel.org, linux-api@...r.kernel.org,
	Tyler Baker <tyler.baker@...aro.org>,
	Olof Johansson <olof@...om.net>,
	Daniel Stone <daniel@...ishbar.org>,
	Arnd Bergmann <arnd@...db.de>
Subject: Re: [PATCH v2 2/3] fbcon: use the cursor blink interval provided by
 vt

On Tue, May 19, 2015 at 04:41:12PM -0700, Greg Kroah-Hartman wrote:
> On Tue, May 19, 2015 at 11:52:29PM +0200, Thierry Reding wrote:
> > On Tue, May 19, 2015 at 02:45:19PM -0700, Kevin Hilman wrote:
> > > On Tue, May 19, 2015 at 2:40 PM, Thierry Reding
> > > <thierry.reding@...il.com> wrote:
> > > > On Tue, May 19, 2015 at 02:15:41PM -0700, Kevin Hilman wrote:
> > > >> On Thu, Mar 26, 2015 at 6:56 AM, Scot Doyle <lkml14@...tdoyle.com> wrote:
> > > >> > vt now provides a cursor blink interval via vc_data. Use this
> > > >> > interval instead of the currently hardcoded 200 msecs. Store it in
> > > >> > fbcon_ops to avoid locking the console in cursor_timer_handler().
> > > >> >
> > > >> > Signed-off-by: Scot Doyle <lkml14@...tdoyle.com>
> > > >> > Acked-by: Pavel Machek <pavel@....cz>
> > > >>
> > > >> This patch hit next-20150519 in the form of commit 27a4c827c34a
> > > >> (fbcon: use the cursor blink interval provided by vt) and has caused
> > > >> boot failure on a handful of ARM platforms when booting a MMC root
> > > >> filesystem.  This error was spotted by the kernelci.org bot on
> > > >> exynos5800-peach-pi[1] and Thierry and Daniel (Cc'd) have seen it on
> > > >> some tegra platforms too.
> > > >>
> > > >> Thierry spotted this commit as a potential cause, and both Daniel and
> > > >> I have reverted and boot tested on exynos5 and tegra respectively and
> > > >> the boot panics disappear.
> > > >
> > > > FWIW, if I apply the below on top of next-20150519 things seem to be
> > > > back to normal as well:
> > > >
> > > > diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c
> > > > index 05b1d1a71ef9..658c34bb9076 100644
> > > > --- a/drivers/video/console/fbcon.c
> > > > +++ b/drivers/video/console/fbcon.c
> > > > @@ -1310,8 +1310,9 @@ static void fbcon_cursor(struct vc_data *vc, int mode)
> > > >                 return;
> > > >
> > > >         ops->cur_blink_jiffies = msecs_to_jiffies(vc->vc_cur_blink_ms);
> > > > -       fbcon_del_cursor_timer(info);
> > > > -       if (!(vc->vc_cursor_type & 0x10))
> > > > +       if (vc->vc_cursor_type & 0x10)
> > > > +               fbcon_del_cursor_timer(info);
> > > > +       else
> > > >                 fbcon_add_cursor_timer(info);
> > > >
> > > >         ops->cursor_flash = (mode == CM_ERASE) ? 0 : 1;
> > > 
> > > Applying this on next-20150519 makes my exynos board happily boot again as well.
> > > 
> > > Tested-by: Kevin Hilman <khilman@...aro.org>
> > 
> > Excellent. Greg, Scot, any opinions on whether or not this is the right
> > thing to do? It restores a bit that looks suspiciously like it snuck in
> > in the original (at least it isn't documented in the commit message).
> > 
> > Greg, feel free to squash this in if everybody agrees this is good to
> > go. If you prefer a patch on top let me know and I'll come up with a
> > proper commit message.
> 
> Please send a real patch and I'll apply it on top, as I can't rebase my
> public tree.

Attached.

Thierry

View attachment "0001-fbcon-Avoid-deleting-a-timer-in-IRQ-context.patch" of type "text/x-diff" (3213 bytes)

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