On to, 2016-02-18 at 17:21 +0200, Mika Kuoppala wrote:
> Cores need to be included into the debug mask. We don't exactly
> know what it does but the spec says it must be enabled. So obey.
>
> Signed-off-by: Mika Kuoppala <[email protected]>
> ---
> drivers/gpu/drm/i915/i915_reg.h | 1 +
> drivers/gpu/drm/i915/intel_runtime_pm.c | 14 ++++++++------
> 2 files changed, 9 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_reg.h
> b/drivers/gpu/drm/i915/i915_reg.h
> index 3774870477c1..f76cbf3e5d1e 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -7568,6 +7568,7 @@ enum skl_disp_power_wells {
> #define DC_STATE_EN_UPTO_DC5_DC6_MASK 0x3
>
> #define DC_STATE_DEBUG _MMIO(0x45520)
> +#define DC_STATE_DEBUG_MASK_CORES (1<<0)
> #define DC_STATE_DEBUG_MASK_MEMORY_UP (1<<1)
>
> /* Please see hsw_read_dcomp() and hsw_write_dcomp() before using
> this register,
> diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c
> b/drivers/gpu/drm/i915/intel_runtime_pm.c
> index cb91540cfbad..1b490c7e4020 100644
> --- a/drivers/gpu/drm/i915/intel_runtime_pm.c
> +++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
> @@ -456,15 +456,17 @@ static void assert_can_disable_dc9(struct
> drm_i915_private *dev_priv)
> */
> }
>
> -static void gen9_set_dc_state_debugmask_memory_up(
> - struct drm_i915_private *dev_priv)
> +static void gen9_set_dc_state_debugmask(struct drm_i915_private
> *dev_priv)
> {
> - uint32_t val;
> + uint32_t val, mask;
> +
> + mask = DC_STATE_DEBUG_MASK_MEMORY_UP |
> + DC_STATE_DEBUG_MASK_CORES;
The BSpec "Sequence to Allow DC5 or DC6" requires this only for BXT
(looks like a recent addition to work around something), but it doesn't
say it's needed for other platforms. The register description doesn't
make a difference though.
Perhaps Art has more info on this, adding him.
>
> /* The below bit doesn't need to be cleared ever afterwards
> */
> val = I915_READ(DC_STATE_DEBUG);
> - if (!(val & DC_STATE_DEBUG_MASK_MEMORY_UP)) {
> - val |= DC_STATE_DEBUG_MASK_MEMORY_UP;
> + if ((val & mask) != mask) {
> + val |= mask;
> I915_WRITE(DC_STATE_DEBUG, val);
> POSTING_READ(DC_STATE_DEBUG);
> }
> @@ -525,7 +527,7 @@ static void gen9_set_dc_state(struct
> drm_i915_private *dev_priv, uint32_t state)
> state = DC_STATE_EN_UPTO_DC5;
>
> if (state & DC_STATE_EN_UPTO_DC5_DC6_MASK)
> - gen9_set_dc_state_debugmask_memory_up(dev_priv);
> + gen9_set_dc_state_debugmask(dev_priv);
>
> val = I915_READ(DC_STATE_EN);
> DRM_DEBUG_KMS("Setting DC state from %02x to %02x\n",
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