Re: [PATCH 12/21] drm/i915: support Haswell-style force waking

Daniel Vetter
2012-06-28T19:38:08Z

On Thu, Jun 28, 2012 at 03:55:40PM -0300, Eugeni Dodonov wrote:
> On Haswell, there is a different register for reading force wake ACKs, and
> all the writes should go into the multi-threaded register, even for the
> legacy force wake.
>
> Also, we have a theorical possibility for the force wake sequence to
> awaken the GT, but return while it hasn't finished bringing up the queue.
> So we properly check those bits as well, to ensure we won't end up in
> half-woken situation.
>
> Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>

This patch didn't survive review with the *shhh* intel top secret *ssshhh*
power docs ;-) It looks like we're supposed to poll for the ack from the
hw on the _same_ reg as we've used in the MT forcewake register until the
bit is set (for get) or cleared (for put).

Also, calling the helper function hsw_wait_gt_ack makes more sense then.
-Daniel

> ---
> drivers/gpu/drm/i915/i915_drv.c | 36 +++++++++++++++++++++++++++++++++++-
> drivers/gpu/drm/i915/i915_drv.h | 3 +++
> drivers/gpu/drm/i915/i915_reg.h | 1 +
> drivers/gpu/drm/i915/intel_pm.c | 4 +++-
> 4 files changed, 42 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index 79be879..73fd38a 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -536,6 +536,39 @@ int __gen6_gt_wait_for_fifo(struct drm_i915_private *dev_priv)
> return ret;
> }
>
> +static inline void __hsw_wait_gt_awake(struct drm_i915_private *dev_priv)
> +{
> + int count = 0;
> +
> + while (count++ < 50) {
> + u32 tmp = I915_READ_NOTRACE(FORCEWAKE_ACK_HSW);
> + if ((tmp & 1) && !(tmp & _MASKED_BIT_ENABLE(~7)))
> + break;
> + udelay(10);
> + }
> +}
> +
> +
> +void hsw_gt_force_wake_get(struct drm_i915_private *dev_priv)
> +{
> + __hsw_wait_gt_awake(dev_priv);
> +
> + I915_WRITE_NOTRACE(FORCEWAKE_MT, _MASKED_BIT_ENABLE(1));
> + POSTING_READ(FORCEWAKE_MT);
> +
> + __hsw_wait_gt_awake(dev_priv);
> +}
> +
> +void hsw_gt_force_wake_put(struct drm_i915_private *dev_priv)
> +{
> + I915_WRITE_NOTRACE(FORCEWAKE_MT, _MASKED_BIT_DISABLE(1));
> +
> + __hsw_wait_gt_awake(dev_priv);
> +
> + /* The below doubles as a POSTING_READ */
> + gen6_gt_check_fifodbg(dev_priv);
> +}
> +
> void vlv_force_wake_get(struct drm_i915_private *dev_priv)
> {
> int count;
> @@ -1161,7 +1194,8 @@ MODULE_LICENSE("GPL and additional rights");
> #define NEEDS_FORCE_WAKE(dev_priv, reg) \
> ((HAS_FORCE_WAKE((dev_priv)->dev)) && \
> ((reg) < 0x40000) && \
> - ((reg) != FORCEWAKE))
> + ((reg) != FORCEWAKE) && \
> + ((reg) != FORCEWAKE_MT))
>
> static bool IS_DISPLAYREG(u32 reg)
> {
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index a0c15ab..e4916a0 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1525,6 +1525,9 @@ extern void __gen6_gt_force_wake_mt_put(struct drm_i915_private *dev_priv);
> extern void vlv_force_wake_get(struct drm_i915_private *dev_priv);
> extern void vlv_force_wake_put(struct drm_i915_private *dev_priv);
>
> +extern void hsw_gt_force_wake_get(struct drm_i915_private *dev_priv);
> +extern void hsw_gt_force_wake_put(struct drm_i915_private *dev_priv);
> +
> /* overlay */
> #ifdef CONFIG_DEBUG_FS
> extern struct intel_overlay_error_state *intel_overlay_capture_error_state(struct drm_device *dev);
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 284965b..2c4be2e 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -4070,6 +4070,7 @@
> #define FORCEWAKE 0xA18C
> #define FORCEWAKE_VLV 0x1300b0
> #define FORCEWAKE_ACK_VLV 0x1300b4
> +#define FORCEWAKE_ACK_HSW 0x130044
> #define FORCEWAKE_ACK 0x130090
> #define FORCEWAKE_MT 0xa188 /* multi-threaded */
> #define FORCEWAKE_MT_ACK 0x130040
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 99bc1f3..0334e42 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -3769,7 +3769,7 @@ void intel_init_pm(struct drm_device *dev)
> dev_priv->display.force_wake_put = __gen6_gt_force_wake_put;
>
> /* IVB configs may use multi-threaded forcewake */
> - if (IS_IVYBRIDGE(dev) || IS_HASWELL(dev)) {
> + if (IS_IVYBRIDGE(dev)) {
> u32 ecobus;
>
> /* A small trick here - if the bios hasn't configured MT forcewake,
> @@ -3842,6 +3842,8 @@ void intel_init_pm(struct drm_device *dev)
> }
> dev_priv->display.init_clock_gating = ivybridge_init_clock_gating;
> dev_priv->display.sanitize_pm = gen6_sanitize_pm;
> + dev_priv->display.force_wake_get = hsw_gt_force_wake_get;
> + dev_priv->display.force_wake_put = hsw_gt_force_wake_put;
> } else
> dev_priv->display.update_wm = NULL;
> } else if (IS_VALLEYVIEW(dev)) {
> --
> 1.7.11.1
>
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--
Daniel Vetter
Mail: daniel@ffwll.ch
Mobile: +41 (0)79 365 57 48