On Mon, 02 Nov 2015, Shobhit Kumar <shobhit.kumar@xxxxxxxxx> 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@xxxxxxxxxxxxxxx>
> Signed-off-by: Shobhit Kumar <shobhit.kumar@xxxxxxxxx>
> ---
> 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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