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    SubjectRe: i915/kms/backlight-combo mode problem
    Add Cc. Michael Chang for he is our i915 expert.

    Hi Melchior,

    於 日,2011-05-08 於 16:05 +0200,Melchior FRANZ 提到:
    >
    > > Does it work to you direct control brightness by access
    > > by /sys/class/backlight/acer-wmi/brightness ?
    >
    > No. A number written to this virtual file is accepted and remembered,
    > but it doesn't actually change the brightness. It takes setpci to do
    > that.
    >

    I thought the video driver still is the KEY component for backlight
    issues, need fix the problem in video driver first.

    >
    >
    > > As I remember, use setpci to control brightness is not recommended
    > > because BIOS or ACPI will also touch brightness level. That will be
    > > better control brightness by the function that was provided by BIOS.
    > > e.g. ACPI or WMI interface, or direct control by EC.
    >
    > Well, sounds plausible. And I wouldn't do it if it weren't the only
    > way at the moment. :-)
    >
    >
    >
    > > That means that will be better fix your Fn key control brightness like
    > > before, you just need press Fn key to change brightness and don't need
    > > have any workaround.
    >
    > OK. I have added a lot of debug messages to intel_panel.c yesterday.
    > All it told me was that it seems to work correctly wiht acpi_osi=Linux.
    > Except that it doesn't actually change the brightness. Without acpi_osi
    > the functions aren't called at all and none of my messages showed up.
    >

    I traced _Q event in your DSDT, when acpi_osi=Linux, it run the Intel
    OpRegion logic for change brightness. And, finally, intel_opregion will
    access the function the were provided by intel_panel. So, the problem
    still back to intel_panel.

    After discuss with Michael chang, we thought there have problem in your
    brightness level after add combination mode:

    vi driver/gpu/drm/i915/intel_panel.c

    void intel_panel_set_backlight(struct drm_device *dev, u32 level)
    {
    struct drm_i915_private *dev_priv = dev->dev_private;
    u32 tmp;

    DRM_DEBUG_DRIVER("set backlight PWM = %d\n", level);

    if (HAS_PCH_SPLIT(dev))
    return intel_pch_panel_set_backlight(dev, level);

    if (is_backlight_combination_mode(dev)){
    u32 max = intel_panel_get_max_backlight(dev);
    u8 lbpc;

    lbpc = level * 0xfe / max + 1;
    level /= lbpc; /* maybe the level changed by lbpc */
    pci_write_config_byte(dev->pdev, PCI_LBPC, lbpc);
    }

    tmp = I915_READ(BLC_PWM_CTL);
    if (IS_PINEVIEW(dev)) {
    tmp &= ~(BACKLIGHT_DUTY_CYCLE_MASK - 1);
    level <<= 1;
    } else
    tmp &= ~BACKLIGHT_DUTY_CYCLE_MASK;
    I915_WRITE(BLC_PWM_CTL, tmp | level);
    }

    We need to know some run time value when intel_panel_set_backlight call by funciton key.
    Please help to apply the attached debug patch to intel_panel.c then attached dmesg.

    >
    >
    > > Looks like current status is we try to fix bko#31522 but the patch
    > > causes your brightness no work by press Fn key even with acpi_osi=Linux.
    > > Does it right?
    >
    > The history is: with acpi_osi=Linux everything worked with 2.6.38-rc8.
    > With 2.6.38 the screen stayed black. The patch that only ignored lbpc=0
    > worked (IIRC) including key adjustment. Later patches broke keys.
    >
    >
    >
    > > replace acpi_osi=Linux by acpi_osi="!Windows 2006"
    > >
    > > Does it also works to you for backlight control?
    >
    > No, doesn't work.
    >

    We can test the acpi_osi="!Windows 2006" again after we fix the i915's
    problem.


    Thank's
    Joey Lee

    The following is debug patch, and please add kernel parameter
    drm.debug=0x02 :

    diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
    index f8f86e5..f62dbd9 100644
    --- a/drivers/gpu/drm/i915/intel_panel.c
    +++ b/drivers/gpu/drm/i915/intel_panel.c
    @@ -236,17 +236,22 @@ void intel_panel_set_backlight(struct drm_device *dev, u32 level)
    u32 max = intel_panel_get_max_backlight(dev);
    u8 lbpc;

    + DRM_DEBUG_DRIVER("set backlight max = % lbpc = level * 0xfe / max + 1;
    + DRM_DEBUG_DRIVER("set backlight lbpc = %d\n", lbpc);
    level /= lbpc;
    pci_write_config_byte(dev->pdev, PCI_LBPC, lbpc);
    }

    tmp = I915_READ(BLC_PWM_CTL);
    + DRM_DEBUG_DRIVER("set backlight tmp(1) = %d\n", tmp);
    if (IS_PINEVIEW(dev)) {
    tmp &= ~(BACKLIGHT_DUTY_CYCLE_MASK - 1);
    level <<= 1;
    } else
    tmp &= ~BACKLIGHT_DUTY_CYCLE_MASK;
    + DRM_DEBUG_DRIVER("set backlight tmp(2) = %d\n", tmp);
    + DRM_DEBUG_DRIVER("set backlight level = %d\n", level);
    I915_WRITE(BLC_PWM_CTL, tmp | level);
    }


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