Attachment 41960 Details for Bug 31803 – Fix backlight combination mode

[patch] Fix backlight combination mode

0001-drm-i915-panel-Fix-application-of-legacy-backlight-v.patch (text/plain), 1.68 KB, created by Chris Wilson on 2011-01-13 05:25:33 UTC

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Creator: Chris Wilson

Created: 2011-01-13 05:25:33 UTC

Size: 1.68 KB

patch

obsolete

>From 036c69e361ca3744b6c26129e2d4b5dbec3b205a Mon Sep 17 00:00:00 2001
>From: Chris Wilson <chris@chris-wilson.co.uk>
>Date: Thu, 13 Jan 2011 12:30:19 +0000
>Subject: [PATCH] drm/i915/panel: Fix application of legacy backlight value
>
>Remove the spurious division by two in getting the current value, and if
>the legacy value is 0xff it is unused. And whilst setting the value, fix
>the rounding.
>
>Reported-by: Nick Bowler <nbowler@draconx.ca>
>Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=31803
>Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
>---
> drivers/gpu/drm/i915/intel_panel.c |   12 ++++++++----
> 1 files changed, 8 insertions(+), 4 deletions(-)
>
>diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
>index c65992d..71ba046 100644
>--- a/drivers/gpu/drm/i915/intel_panel.c
>+++ b/drivers/gpu/drm/i915/intel_panel.c
>@@ -205,10 +205,11 @@ u32 intel_panel_get_backlight(struct drm_device *dev)
> 		if (is_backlight_combination_mode(dev)){
> 			u8 lbpc;
> 
>-			val &= ~1;
> 			pci_read_config_byte(dev->pdev, PCI_LBPC, &lbpc);
>+			/* Report the value in [0:max] i.e. always multiplied
>+			 * by lbpc even if the hardware does not (0xff).
>+			 */
> 			val *= lbpc;
>-			val >>= 1;
> 		}
> 	}
> 
>@@ -237,9 +238,12 @@ void intel_panel_set_backlight(struct drm_device *dev, u32 level)
> 		u32 max = intel_panel_get_max_backlight(dev);
> 		u8 lpbc;
> 
>-		lpbc = level * 0xfe / max + 1;
>-		level /= lpbc;
>+		lpbc = (level * 0xfe + max-1) / max + 1;
> 		pci_write_config_byte(dev->pdev, PCI_LBPC, lpbc);
>+
>+		/* The hardware is tricksy and treats lpbc == 0xff specially */
>+		max = lpbc == 0xff ? 0xff : 0xff * lpbc;
>+		level = (level + max-1) / max;
> 	}
> 
> 	tmp = I915_READ(BLC_PWM_CTL);
>-- 
>1.7.2.3
>

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