linux-kernel - Re: [PATCH 8/8] ARM / shmobile: Support for I/O PM domains for SH7372 (v5)

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Date:	Sun, 10 Jul 2011 13:45:35 +0200
From:	Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:	Magnus Damm <magnus.damm@...il.com>
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>,
	Linux PM mailing list <linux-pm@...ts.linux-foundation.org>,
	"Greg Kroah-Hartman" <gregkh@...e.de>,
	Paul Walmsley <paul@...an.com>, Kevin Hilman <khilman@...com>,
	Alan Stern <stern@...land.harvard.edu>,
	LKML <linux-kernel@...r.kernel.org>, linux-sh@...r.kernel.org
Subject: Re: [PATCH 8/8] ARM / shmobile: Support for I/O PM domains for SH7372 (v5)

Hi Magnus,

On Wednesday 15 June 2011 16:17:15 Magnus Damm wrote:
> On Wed, Jun 15, 2011 at 6:16 AM, Rafael J. Wysocki <rjw@...k.pl> wrote:
> > On Tuesday, June 14, 2011, Magnus Damm wrote:
> >> On Sun, Jun 12, 2011 at 5:40 AM, Rafael J. Wysocki <rjw@...k.pl> wrote:
> >> > From: Rafael J. Wysocki <rjw@...k.pl>
> >> > 
> >> > Use the generic power domains support introduced by the previous
> >> > patch to implement support for power domains on SH7372.
> >> > 
> >> > Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
> >> > ---
> >> 
> >> Thanks for your work on this. I just tried this on my Mackerel board,
> >> but I can't seem to get the pd_power_up() and pd_power_down()
> >> callbacks to be executed. It is probably a misconfiguration from my
> >> side.
> > 
> > They trigger for me e.g. after doing
> > 
> > # echo 3 > /sys/devices/platform/sh_mobile_lcdc_fb.0/graphics/fb0/blank
> > 
> > Attached is the .config I've been using.
> 
> Thanks, I can trigger using sysfs and your kernel configuration.
> 
> However, I assumed it also would work when the sceen saver kicked in.
> I recall it being fbcon that controls the screen save, perhaps
> something else. So just wait a bit and see if you also can reproduce
> it. The console gets black but the power is still on...

That's because, by default, the VT layer will use FB_BLANK_NORMAL mode when 
blanking the console. Switching that to FB_BLANK_VSYNC_SUSPEND, 
FB_BLANK_HSYNC_SUSPEND or FB_BLANK_POWERDOWN with TIOCLINUX(TIOC_SETVESABLANK) 
results in the device being runtime-suspended when the console is blanked.

> Also forcing to go back to powered-on state (see below) doesn't work that
> well: # echo 0 >
> /sys/devices/platform/sh_mobile_lcdc_fb.0/graphics/fb0/blank
> 
> It looks like we loose the panning information somehow. Most likely a LCDC
> driver bug. Unless the driver callbacks are not being invoked as expected.
>
> Also, there is garbage in on the screen if FB_SH_MOBILE_MERAM is
> enabled. The MERAM hardware is a 1.5 MiB memory block that can be used
> as a LCD cache. It sits in the same hardware power domain as the
> LCDCs. I don't think the MERAM software supports power down
> unfortunately. Disabling MERAM support removes the garbage on the
> screen.

-- 
Regards,

Laurent Pinchart
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