On Tue, May 24, 2016 at 03:38:33PM +0300, Imre Deak wrote: > I noticed that during S4 resume BIOS incorrectly sets bits 18, 19 which > are reserved/MBZ and sets the decimal frequency fields to all 0xff in > the CDCLK register. The result is a hard lockup as display register > accesses are attempted later. Work around this by sanitizing the CDCLK > PLL/dividers the same way it's done on SKL. > > While this is clearly a BIOS bug which should be fixed separately, it > doesn't hurt to check/sanitize this regardless. > > v2: > - Use the same condition for VCO and CDCLK in broxton_init_cdclk as is > used in skl_init_cdclk for the same purpose. > > CC: Ville Syrjälä <[email protected]> > Signed-off-by: Imre Deak <[email protected]>
Reviewed-by: Ville Syrjälä <[email protected]> > --- > drivers/gpu/drm/i915/intel_display.c | 51 > ++++++++++++++++++++++++++++++++++-- > 1 file changed, 49 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/i915/intel_display.c > b/drivers/gpu/drm/i915/intel_display.c > index 47b2466..19f947f 100644 > --- a/drivers/gpu/drm/i915/intel_display.c > +++ b/drivers/gpu/drm/i915/intel_display.c > @@ -5412,11 +5412,58 @@ static void broxton_set_cdclk(struct drm_i915_private > *dev_priv, int cdclk) > intel_update_cdclk(dev_priv->dev); > } > > +static void bxt_sanitize_cdclk(struct drm_i915_private *dev_priv) > +{ > + u32 cdctl, expected; > + > + intel_update_cdclk(dev_priv->dev); > + > + if (dev_priv->cdclk_pll.vco == 0 || > + dev_priv->cdclk_freq == dev_priv->cdclk_pll.ref) > + goto sanitize; > + > + /* DPLL okay; verify the cdclock > + * > + * Some BIOS versions leave an incorrect decimal frequency value and > + * set reserved MBZ bits in CDCLK_CTL at least during exiting from S4, > + * so sanitize this register. > + */ > + cdctl = I915_READ(CDCLK_CTL); > + /* > + * Let's ignore the pipe field, since BIOS could have configured the > + * dividers both synching to an active pipe, or asynchronously > + * (PIPE_NONE). > + */ > + cdctl &= ~BXT_CDCLK_CD2X_PIPE_NONE; > + > + expected = (cdctl & BXT_CDCLK_CD2X_DIV_SEL_MASK) | > + skl_cdclk_decimal(dev_priv->cdclk_freq); > + /* > + * Disable SSA Precharge when CD clock frequency < 500 MHz, > + * enable otherwise. > + */ > + if (dev_priv->cdclk_freq >= 500000) > + expected |= BXT_CDCLK_SSA_PRECHARGE_ENABLE; > + > + if (cdctl == expected) > + /* All well; nothing to sanitize */ > + return; > + > +sanitize: > + DRM_DEBUG_KMS("Sanitizing cdclk programmed by pre-os\n"); > + > + /* force cdclk programming */ > + dev_priv->cdclk_freq = 0; > + > + /* force full PLL disable + enable */ > + dev_priv->cdclk_pll.vco = -1; > +} > + > void broxton_init_cdclk(struct drm_i915_private *dev_priv) > { > - intel_update_cdclk(dev_priv->dev); > + bxt_sanitize_cdclk(dev_priv); > > - if (dev_priv->cdclk_pll.vco != 0) > + if (dev_priv->cdclk_freq != 0 && dev_priv->cdclk_pll.vco != 0) > return; > > /* > -- > 2.5.0 -- Ville Syrjälä Intel OTC _______________________________________________ Intel-gfx mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/intel-gfx
