Re: [PATCH] drm/i915/skl: While sanitizing cdclock check the SWF18 as well

[Jani Nikula <jani.nikula@linux.intel.com>]

On Mon, 02 Nov 2015, Shobhit Kumar <shobhit.kumar@intel.com> wrote:
> SWF18 is set if the display has been intialized by the pre-os. It
> also gives what configuration is enabled on which pipe. The DPLL and
> CDCLK verification checks can fail as the pre-os does initialize the
> DPLL for Audio codec initialization. So fisrt check if SWF18 is set and
> then follow through with other DPLL and CDCLK verification.

Can we universally trust all bios/gop/bootloader/whatnot to have
initialized this? What if it's not set?

BR,
Jani.



>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Signed-off-by: Shobhit Kumar <shobhit.kumar@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_reg.h      | 3 +++
>  drivers/gpu/drm/i915/intel_display.c | 8 ++++++++
>  2 files changed, 11 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 9ee9481..bd476ff 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -5006,6 +5006,9 @@ enum skl_disp_power_wells {
>  #define SWF1(i)	(dev_priv->info.display_mmio_offset + 0x71410 + (i) * 4)
>  #define SWF3(i)	(dev_priv->info.display_mmio_offset + 0x72414 + (i) * 4)
>  
> +/* VBIOS flag for display initialized status */
> +#define GEN6_SWF18  (dev_priv->info.display_mmio_offset + 0x4F060)
> +
>  /* Pipe B */
>  #define _PIPEBDSL		(dev_priv->info.display_mmio_offset + 0x71000)
>  #define _PIPEBCONF		(dev_priv->info.display_mmio_offset + 0x71008)
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 103cacb..0ecb35c 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -5761,6 +5761,14 @@ int skl_sanitize_cdclk(struct drm_i915_private *dev_priv)
>  	uint32_t cdctl = I915_READ(CDCLK_CTL);
>  	int freq = dev_priv->skl_boot_cdclk;
>  
> +	/*
> +	 * check if the pre-os intialized the display
> +	 * There is SWF18 scratchpad register defined which is set by the
> +	 * pre-os which can be used by the OS drivers to check the status
> +	 */
> +	if ((I915_READ(GEN6_SWF18) & 0x00FFFF) == 0)
> +		goto sanitize;
> +
>  	/* Is PLL enabled and locked ? */
>  	if (!((lcpll1 & LCPLL_PLL_ENABLE) && (lcpll1 & LCPLL_PLL_LOCK)))
>  		goto sanitize;

-- 
Jani Nikula, Intel Open Source Technology Center
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