Re: [PATCH 08/12] drm/i915: Make sure PND deadline mode is enabled on VLV/CHV

Jesse Barnes
2015-02-27T20:38:11Z

On 02/10/2015 05:28 AM, ville.syrjala@linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> Poke at the CBR1_VLV register during init_clock_gating to make sure the
> PND deadline scheme is used.
>
> The hardware has two modes of operation wrt. watermarks:
>
> 1) PND deadline mode:
> - memory request deadline is calculated from actual FIFO level * DDL
> - WM1 watermark values are unused (AFAIK)
> - WM watermark level defines when to start fetching data from memory
> (assuming trickle feed is not used)
>
> 2) backup mode
> - deadline is based on FIFO status, DDL is unused
> - FIFO split into three regions with WM and WM1 watermarks, each
> part specifying a different FIFO status
>
> We want to use the PND deadline mode, so let's make sure the chicken
> bit is in the correct position on init.
>
> Also take the opportunity to refactor the shared code between VLV and
> CHV to a shared function.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
> drivers/gpu/drm/i915/i915_reg.h | 3 +++
> drivers/gpu/drm/i915/intel_pm.c | 19 +++++++++++++------
> 2 files changed, 16 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 433d7e7..5d377df 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -4177,6 +4177,9 @@ enum skl_disp_power_wells {
> #define DDL_PRECISION_LOW (0<<7)
> #define DRAIN_LATENCY_MASK 0x7f
>
> +#define CBR1_VLV (VLV_DISPLAY_BASE + 0x70400)
> +#define CBR_PND_DEADLINE_DISABLE (1<<31)
> +
> /* FIFO watermark sizes etc */
> #define G4X_FIFO_LINE_SIZE 64
> #define I915_FIFO_LINE_SIZE 64
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index e53038e..c021e92 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -6197,11 +6197,22 @@ static void ivybridge_init_clock_gating(struct drm_device *dev)
> gen6_check_mch_setup(dev);
> }
>
> +static void vlv_init_display_clock_gating(struct drm_i915_private *dev_priv)
> +{
> + I915_WRITE(DSPCLK_GATE_D, VRHUNIT_CLOCK_GATE_DISABLE);
> +
> + /*
> + * Disable trickle feed and enable pnd deadline calculation
> + */
> + I915_WRITE(MI_ARB_VLV, MI_ARB_DISPLAY_TRICKLE_FEED_DISABLE);
> + I915_WRITE(CBR1_VLV, 0);
> +}
> +
> static void valleyview_init_clock_gating(struct drm_device *dev)
> {
> struct drm_i915_private *dev_priv = dev->dev_private;
>
> - I915_WRITE(DSPCLK_GATE_D, VRHUNIT_CLOCK_GATE_DISABLE);
> + vlv_init_display_clock_gating(dev_priv);
>
> /* WaDisableEarlyCull:vlv */
> I915_WRITE(_3D_CHICKEN3,
> @@ -6249,8 +6260,6 @@ static void valleyview_init_clock_gating(struct drm_device *dev)
> I915_WRITE(GEN7_UCGCTL4,
> I915_READ(GEN7_UCGCTL4) | GEN7_L3BANK2X_CLOCK_GATE_DISABLE);
>
> - I915_WRITE(MI_ARB_VLV, MI_ARB_DISPLAY_TRICKLE_FEED_DISABLE);
> -
> /*
> * BSpec says this must be set, even though
> * WaDisable4x2SubspanOptimization isn't listed for VLV.
> @@ -6287,9 +6296,7 @@ static void cherryview_init_clock_gating(struct drm_device *dev)
> {
> struct drm_i915_private *dev_priv = dev->dev_private;
>
> - I915_WRITE(DSPCLK_GATE_D, VRHUNIT_CLOCK_GATE_DISABLE);
> -
> - I915_WRITE(MI_ARB_VLV, MI_ARB_DISPLAY_TRICKLE_FEED_DISABLE);
> + vlv_init_display_clock_gating(dev_priv);
>
> /* WaVSRefCountFullforceMissDisable:chv */
> /* WaDSRefCountFullforceMissDisable:chv */
>

Is the deadline mode preference documented somewhere? Do we need
another bspec bug filed?

Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>