Re: [PATCH 15/19] drm/i915: HSW cdclk support

Ville Syrjälä
2015-04-07T08:28:17Z

On Tue, Apr 07, 2015 at 11:57:23AM +0530, Sivakumar Thulasimani wrote:
>
>
> On 3/31/2015 4:44 PM, Mika Kahola wrote:
> > Implement support for changing the cdclk frequency during runtime on
> > HSW. VLV/CHV already have support for this, so we can follow their
> > example for the most part. Only the actual hardware programming differs,
> > the rest is pretty much the same.
> >
> > The pipe pixel rate stuff is handled a bit differently for now due to
> > the difference in pch vs. gmch pfit handling. Eventually we should unify
> > that part to eliminate what is essentially duplicated code.
> >
> > v2: Grab rps.hw_lock around sandybridge_pcode_write()
> > v3: Rebase due to power well vs. .global_resources() reordering
> > v4: Rebase due to .global_resources() reordering for Haswell
> >
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > Signed-off-by: Mika Kahola <mika.kahola@intel.com>
> > ---
> > drivers/gpu/drm/i915/i915_reg.h | 3 +
> > drivers/gpu/drm/i915/intel_display.c | 161 ++++++++++++++++++++++++++++++++++-
> > 2 files changed, 161 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> > index f26ebd2..b25f712 100644
> > --- a/drivers/gpu/drm/i915/i915_reg.h
> > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > @@ -6244,6 +6244,7 @@ enum skl_disp_power_wells {
> > #define GEN6_PCODE_WRITE_D_COMP 0x11
> > #define GEN6_ENCODE_RC6_VID(mv) (((mv) - 245) / 5)
> > #define GEN6_DECODE_RC6_VID(vids) (((vids) * 5) + 245)
> > +#define HSW_PCODE_DE_WRITE_FREQ_REQ 0x17
> > #define DISPLAY_IPS_CONTROL 0x19
> > #define HSW_PCODE_DYNAMIC_DUTY_CYCLE_CONTROL 0x1A
> > #define GEN6_PCODE_DATA 0x138128
> > @@ -6698,10 +6699,12 @@ enum skl_disp_power_wells {
> > #define LCPLL_PLL_LOCK (1<<30)
> > #define LCPLL_CLK_FREQ_MASK (3<<26)
> > #define LCPLL_CLK_FREQ_450 (0<<26)
> > +#define LCPLL_CLK_FREQ_ALT_HSW (1<<26) /* 337.5 (ULX) or 540 */
> > #define LCPLL_CLK_FREQ_54O_BDW (1<<26)
> > #define LCPLL_CLK_FREQ_337_5_BDW (2<<26)
> > #define LCPLL_CLK_FREQ_675_BDW (3<<26)
> > #define LCPLL_CD_CLOCK_DISABLE (1<<25)
> > +#define LCPLL_ROOT_CD_CLOCK_DISABLE (1<<24)
> > #define LCPLL_CD2X_CLOCK_DISABLE (1<<23)
> > #define LCPLL_POWER_DOWN_ALLOW (1<<22)
> > #define LCPLL_CD_SOURCE_FCLK (1<<21)
> > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > index 3752d5e..cce7103 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -5012,7 +5012,16 @@ static void intel_update_max_cdclk(struct drm_device *dev)
> > {
> > struct drm_i915_private *dev_priv = dev->dev_private;
> >
> > - if (IS_VALLEYVIEW(dev)) {
> > + if (IS_HASWELL(dev)) {
> > + if (I915_READ(FUSE_STRAP) & HSW_CDCLK_LIMIT)
> > + dev_priv->max_cdclk_freq = 450000;
> > + else if (IS_HSW_ULX(dev))
> > + dev_priv->max_cdclk_freq = 337500;
> > + else if (IS_HSW_ULT(dev))
> > + dev_priv->max_cdclk_freq = 450000;
> > + else
> > + dev_priv->max_cdclk_freq = 540000;
> > + } else if (IS_VALLEYVIEW(dev)) {
> > dev_priv->max_cdclk_freq = 400000;
> > } else {
> > /* otherwise assume cdclk is fixed */
> > @@ -8773,6 +8782,144 @@ void hsw_enable_pc8(struct drm_i915_private *dev_priv)
> > hsw_disable_lcpll(dev_priv, true, true);
> > }
> >
> > +/* compute the max rate for new configuration */
> > +static int ilk_max_pixel_rate(struct drm_i915_private *dev_priv)
> > +{
> > + struct drm_device *dev = dev_priv->dev;
> > + struct intel_crtc *crtc;
> > + int max_pixel_rate = 0;
> > +
> > + for_each_intel_crtc(dev, crtc) {
> > + if (crtc->new_enabled)
> > + max_pixel_rate = max(max_pixel_rate,
> > + ilk_pipe_pixel_rate(crtc->new_config));
> > + }
> > +
> > + return max_pixel_rate;
> > +}
> > +
> > +static int haswell_calc_cdclk(struct drm_i915_private *dev_priv,
> > + int max_pixel_rate)
> > +{
> > + int cdclk;
> > +
> > + /*
> > + * FIXME should also account for plane ratio
> > + * once 64bpp pixel formats are supported.
> > + */
> > + if (max_pixel_rate > 450000)
> > + cdclk = 540000;
> > + else if (max_pixel_rate > 337500 || !IS_HSW_ULX(dev_priv))
> > + cdclk = 450000;
> > + else
> > + cdclk = 337500;
> > +
> > + /*
> > + * FIXME move the cdclk caclulation to
> > + * compute_config() so we can fail gracegully.
> > + */
> > + if (cdclk > dev_priv->max_cdclk_freq) {
> > + DRM_ERROR("requested cdclk (%d kHz) exceeds max (%d kHz)\n",
> > + cdclk, dev_priv->max_cdclk_freq);
> > + cdclk = dev_priv->max_cdclk_freq;
> > + }
> > +
> > + return cdclk;
> > +}
> won't this return 337MHz even for platforms that have HSW_CDCLK_LIMIT is
> set ? this should return 450MHz if this fuse is set

I'm not sure ULX machines would ever have HSW_CDCLK_LIMIT set. But
having a check for it should do no harm so might as well I suppose.

--
Ville Syrjälä
Intel OTC