linux-kernel - Re: [PATCH] Add Intel ACPI IGD OpRegion support

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Date:	Wed, 6 Aug 2008 07:34:41 +0100
From:	Matthew Garrett <mjg59@...f.ucam.org>
To:	Henrique de Moraes Holschuh <hmh@....eng.br>
Cc:	Yves-Alexis Perez <corsac@...ian.org>, airlied@...ux.ie,
	linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org
Subject: Re: [PATCH] Add Intel ACPI IGD OpRegion support

On Tue, Aug 05, 2008 at 11:32:48PM -0300, Henrique de Moraes Holschuh wrote:
> On Wed, 06 Aug 2008, Matthew Garrett wrote:
> > The 750ms delay is from thinkpad-acpi. I sent a patch to Henrique which 
> > makes it go away, but I'm not entirely sure what the ACPI method 
> > concerned is supposed to be doing. The opregion code won't currently run 
> > until X is started because the drm layer requires X to be the foreground 
> > vt before handling IRQs.
> 
> Well, for what is it worth, thinkpad-acpi has a knob (brightness_mode) which
> can be used.  Set it to CMOS mode (see docs).  From what I recall, it should
> do what your patch does.

It doesn't seem to, no. I should have been clearer - the delay is in the 
DSDT (not thinkpad-acpi itself), but there's a Thinkpad-specific ACPI 
call that seems to be needed in order to delay it. Here's the patch 
again.

diff --git a/drivers/misc/thinkpad_acpi.c b/drivers/misc/thinkpad_acpi.c
index b596929..bbc45c8 100644
--- a/drivers/misc/thinkpad_acpi.c
+++ b/drivers/misc/thinkpad_acpi.c
@@ -899,6 +899,9 @@ static int __init tpacpi_check_std_acpi_brightness_support(void)
 
 	if (ACPI_SUCCESS(status) && bcl_levels > 2) {
 		tp_features.bright_acpimode = 1;
+		/* Set ACPI mode */
+		if (!acpi_evalf(hkey_handle, NULL, "PWMS", "vd", 0))
+			printk(TPACPI_INFO "Failed to claim backlight\n");
 		return (bcl_levels - 2);
 	}

-- 
Matthew Garrett | mjg59@...f.ucam.org
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