Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752433Ab1CJIZZ (ORCPT ); Thu, 10 Mar 2011 03:25:25 -0500 Received: from cantor2.suse.de ([195.135.220.15]:38928 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752123Ab1CJIZW (ORCPT ); Thu, 10 Mar 2011 03:25:22 -0500 Date: Thu, 10 Mar 2011 09:25:21 +0100 Message-ID: From: Takashi Iwai To: "Indan Zupancic" Cc: "Linus Torvalds" , "Alex Riesen" , "Jesse Barnes" , "DRI mailing list" , "Chris Wilson" , "Linux Kernel Mailing List" , "Tino Keitel" , stable@kernel.org Subject: Re: [PATCH] fix backlight brightness on intel LVDS panel after reopening lid In-Reply-To: References: <20110216192658.GA7225@blimp.localdomain> <20110217221329.GA3332@x61.home> <3f792aaf90cf0b3d49be21baa2682d5d.squirrel@webmail.greenhost.nl> <20110222130440.21a27714@jbarnes-desktop> <20110222223120.GA3567@x61.home> <3e6f092bd0aa54fd6b9eb524f6c87ecf.squirrel@webmail.greenhost.nl> <1a06e2711df021a802d609ad1a75db17.squirrel@webmail.greenhost.nl> User-Agent: Wanderlust/2.15.6 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.7 Emacs/23.2 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5446 Lines: 162 At Thu, 10 Mar 2011 08:49:37 +0100, Takashi Iwai wrote: > > At Thu, 10 Mar 2011 06:50:09 +0100 (CET), > Indan Zupancic wrote: > > > > Hello, > > > > On Fri, March 4, 2011 19:47, Linus Torvalds wrote: > > > Alex, can you confirm that the revert of 951f3512dba5 plus the > > > one-liner patch from Takashi that Indan quoted also works for you? > > > > > > Linus > > > > > > On Thu, Mar 3, 2011 at 10:53 PM, Indan Zupancic wrote: > > >> > > >> So please revert my patch and apply Takashi Iwai's, which fixes the > > >> most immediate bug without changing anything else. This should go > > >> in stable too. > > > > > > > I found another backlight bug: > > > > When suspending intel_panel_disable_backlight() is never called, > > but intel_panel_enable_backlight() is called at resume. With the > > effect that if the brightness was ever changed after screen > > blanking, the wrong brightness gets restored. > > > > This explains the weird behaviour I've seen. I didn't see it with > > combination mode, because then the brightness is always the same > > (zero or the maximum, the BIOS only uses LBPC on my system.) I'll > > send a patch in a moment. > > > > Alternative for reverting the combination mode removal (I can also > > redo the patch against the revert and Takashi's patch, if that's > > preferred): > > > > -- > > > > drm/i915: Do handle backlight combination mode specially > > > > Add back the combination mode check, but with slightly cleaner code > > and the weirdness removed: No val >>= 1, but also no val &= ~1. The > > old code probably confused bit 0 with BLM_LEGACY_MODE, which is bit 16. > > The other change is clearer calculations: Just check for zero level > > explicitly instead of avoiding the divide-by-zero. > > > > Signed-off-by: Indan Zupancic > > > > --- > > > > diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c > > index d860abe..b05631a 100644 > > --- a/drivers/gpu/drm/i915/intel_panel.c > > +++ b/drivers/gpu/drm/i915/intel_panel.c > > @@ -30,6 +30,10 @@ > > > > #include "intel_drv.h" > > > > +#define PCI_LBPC 0xf4 /* legacy/combination backlight modes */ > > +#define BLM_COMBINATION_MODE (1 << 30) > > +#define BLM_LEGACY_MODE (1 << 16) > > + > > void > > intel_fixed_panel_mode(struct drm_display_mode *fixed_mode, > > struct drm_display_mode *adjusted_mode) > > @@ -110,6 +114,22 @@ done: > > dev_priv->pch_pf_size = (width << 16) | height; > > } > > > > +/* > > + * What about gen 3? If there are no gen 3 systems with ASLE, > > + * then it doesn't matter, as we don't need to change the > > + * brightness. But then the gen 2 check can be removed too. > > + */ > > +static int is_backlight_combination_mode(struct drm_device *dev) > > +{ > > + struct drm_i915_private *dev_priv = dev->dev_private; > > + > > + if (INTEL_INFO(dev)->gen >= 4) > > + return I915_READ(BLC_PWM_CTL2) & BLM_COMBINATION_MODE; > > + if (IS_GEN2(dev)) > > + return I915_READ(BLC_PWM_CTL) & BLM_LEGACY_MODE; > > + return 0; > > +} > > + > > static u32 i915_read_blc_pwm_ctl(struct drm_i915_private *dev_priv) > > { > > u32 val; > > @@ -163,9 +183,12 @@ u32 intel_panel_get_max_backlight(struct drm_device *dev) > > max >>= 17; > > } else { > > max >>= 16; > > + /* Ignore BLM_LEGACY_MODE bit */ > > if (INTEL_INFO(dev)->gen < 4) > > max &= ~1; > > } > > + if (is_backlight_combination_mode(dev)) > > + max *= 0xff; > > } > > > > DRM_DEBUG_DRIVER("max backlight PWM = %d\n", max); > > @@ -183,6 +206,12 @@ u32 intel_panel_get_backlight(struct drm_device *dev) > > val = I915_READ(BLC_PWM_CTL) & BACKLIGHT_DUTY_CYCLE_MASK; > > if (IS_PINEVIEW(dev)) > > val >>= 1; > > + if (is_backlight_combination_mode(dev)){ > > + u8 lbpc; > > + > > + pci_read_config_byte(dev->pdev, PCI_LBPC, &lbpc); > > + val *= lbpc; > > + } > > } > > > > DRM_DEBUG_DRIVER("get backlight PWM = %d\n", val); > > @@ -205,6 +234,15 @@ void intel_panel_set_backlight(struct drm_device *dev, u32 level) > > > > if (HAS_PCH_SPLIT(dev)) > > return intel_pch_panel_set_backlight(dev, level); > > + > > + if (level && is_backlight_combination_mode(dev)){ > > + u32 max = intel_panel_get_max_backlight(dev); > > + u8 lpbc; > > + > > + lpbc = level * 0xff / max; > > + level /= lpbc; > > Hmm, I don't think this calculation is correct. This would result > in level of opregion over its limit. For example, assume the level > max = 100, so total max = 25500. Passing level=150 here will be: > > lbpc = 150 * 0xff / 25500 = 1.5 = 1 > level = 150 / 1 = 150, which is over limit. > > More worse, lbpc can be zero when level is below 100 in the case > above... That is, Chris' original code in that portion was correct: if (is_backlight_combination_mode(dev)){ u32 max = intel_panel_get_max_backlight(dev); u8 lpbc; lpbc = level * 0xfe / max + 1; level /= lpbc; pci_write_config_byte(dev->pdev, PCI_LBPC, lpbc); } This will fit within the right range. Though, changing like below will give a bit better calculation, closer to the real level. lpbc = level * 0xfe / max + 1; level = (level + lpbc / 2) / lpbc; Takashi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/