On Wed, 11 Sep 2013, Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx> wrote:
> From: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
>
> Boot params quirks_set and quirks_mask allow the user to enable or
> inhibit any dmi-matched quirks, overriding the dmi match table. Examples:
>
> i915.quirks_set=0x2 - enables QUIRK_LVDS_SSC_DISABLE
> i915.quirks_set=0x8 - enables QUIRK_NO_PCH_PWM_ENABLE
> i915.quirks_mask=0x8 - disables QUIRK_NO_PCH_PWM_ENABLE
> i915.quirks_mask=0xFF - disables all quirks
While I admit this can be used to workaround issues with certain
machines, this is a hack that exposes an implementation detail to the
userspace, and carves it into the stone. Any user of it would have to
look at the kernel source to make a smart choice of parameters; more
likely forums would start filling with tips what to set.
So NAK from me.
That said, I think we still have a few stones unturned wrt backlight and
what BIOS does in UEFI mode.
Cheers,
Jani.
>
> Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/intel_display.c | 15 +++++++++++++++
> 1 file changed, 15 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 1eabca3..12607f2 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -10043,8 +10043,19 @@ static struct intel_quirk intel_quirks[] = {
> { 0x0166, 0x1028, 0x058b, quirk_no_pcm_pwm_enable },
> };
>
> +unsigned long i915_quirks_set __read_mostly = 0;
> +module_param_named(quirks_set, i915_quirks_set, ulong, 0600);
> +MODULE_PARM_DESC(quirks_set,
> + "Enable specified quirks bits.");
> +
> +unsigned long i915_quirks_mask __read_mostly = 0;
> +module_param_named(quirks_mask, i915_quirks_mask, ulong, 0600);
> +MODULE_PARM_DESC(quirks_mask,
> + "Disable specified quirks bits (override dmi match).");
> +
> static void intel_init_quirks(struct drm_device *dev)
> {
> + struct drm_i915_private *dev_priv = dev->dev_private;
> struct pci_dev *d = dev->pdev;
> int i;
>
> @@ -10062,6 +10073,10 @@ static void intel_init_quirks(struct drm_device *dev)
> if (dmi_check_system(*intel_dmi_quirks[i].dmi_id_list) != 0)
> intel_dmi_quirks[i].hook(dev);
> }
> +
> + /* handle user-specified quirks overrides */
> + dev_priv->quirks |= i915_quirks_set;
> + dev_priv->quirks &= ~i915_quirks_mask;
> }
>
> /* Disable the VGA plane that we never use */
> --
> 1.8.1.4
>
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--
Jani Nikula, Intel Open Source Technology Center
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