[Intel-gfx] [PATCH] drm/i915: enable memory self refresh on 945GM

[Li Peng]

On Wed, 2009-12-02 at 11:11 +0800, Fu Michael wrote:
> Li Peng wrote:
> > I did some test and found that memory self refresh on 945GM
> > isn't really enabled in commit 652c39. On 945, we need to use
> > bit 31 of FW_BLC_SELF to enable the write to self refresh bit
> > and bit 16 to enable the write of self refresh watermark.
> >
> > This patch enables memory self refresh on 945GM when graphics
> > is idle, and disable self refresh when it is busy. It can save
> > about 0.2W idle power on the netbook with 945GSE chipset.
> >
> > Signed-off-by: Li Peng <peng.li at intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_reg.h      |    4 +++-
> >  drivers/gpu/drm/i915/intel_display.c |   23 ++++++++++++++++++++++-
> >  2 files changed, 25 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> > index 1687edf..93b5077 100644
> > --- a/drivers/gpu/drm/i915/i915_reg.h
> > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > @@ -301,7 +301,9 @@
> >  #define FW_BLC		0x020d8
> >  #define FW_BLC2	 	0x020dc
> >  #define FW_BLC_SELF	0x020e0 /* 915+ only */
> > -#define   FW_BLC_SELF_EN (1<<15)
> > +#define   FW_BLC_SELF_EN_MASK      (1<<31)
> > +#define   FW_BLC_SELF_FIFO_MASK    (1<<16)
> > +#define   FW_BLC_SELF_EN           (1<<15)
> >  #define MM_BURST_LENGTH     0x00700000
> >  #define MM_FIFO_WATERMARK   0x0001F000
> >  #define LM_BURST_LENGTH     0x00000700
> > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > index 3ba6546..9b96439 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -2580,7 +2580,10 @@ static void i9xx_update_wm(struct drm_device *dev, int planea_clock,
> >  		srwm = total_size - sr_entries;
> >  		if (srwm < 0)
> >  			srwm = 1;
> > -		I915_WRITE(FW_BLC_SELF, FW_BLC_SELF_EN | (srwm & 0x3f));
> > +		if (IS_I945GM(dev))
> > +			I915_WRITE(FW_BLC_SELF, FW_BLC_SELF_FIFO_MASK | (srwm & 0xff));
> > +		else
> > +			I915_WRITE(FW_BLC_SELF, FW_BLC_SELF_EN | (srwm & 0x3f));
> >  	}
> >  
> >  	DRM_DEBUG("Setting FIFO watermarks - A: %d, B: %d, C: %d, SR %d\n",
> >   
> 915GM's SR_EN bit is in INSTPM:12 rather than in FW_BLC_SELF reg.
> 
Thanks for pointing out, I will fix it.

> There seems no need to explicitly disable SR bit. system should be able 
> to use it automatically when condition is met. Do you see any issue 
> without below hunk?

I have tried that, just enabling SR bit and setting srwm in
i9xx_update_wm(), but X got frozen after boot, so I add the 
code to disable SR explicitly. Maybe H/W isn't that smart :)

> 
> > @@ -3671,11 +3674,23 @@ static void intel_gpu_idle_timer(unsigned long arg)
> >  void intel_increase_renderclock(struct drm_device *dev, bool schedule)
> >  {
> >  	drm_i915_private_t *dev_priv = dev->dev_private;
> > +	u32 fw_blc_self;
> > +	int need_schedule = 0;
> >  
> >  	if (IS_IGDNG(dev))
> >  		return;
> >  
> > +	if (IS_I945GM(dev)) {
> > +		DRM_DEBUG("disable memory self refresh on 945\n");
> > +		fw_blc_self = I915_READ(FW_BLC_SELF);
> > +		fw_blc_self &= ~FW_BLC_SELF_EN;
> > +		I915_WRITE(FW_BLC_SELF, fw_blc_self | FW_BLC_SELF_EN_MASK);
> > +		need_schedule = 1;
> > +	}
> > +
> >  	if (!dev_priv->render_reclock_avail) {
> > +		if (need_schedule)
> > +			goto schedule_timer;
> >  		DRM_DEBUG("not reclocking render clock\n");
> >  		return;
> >  	}
> > @@ -3688,6 +3703,7 @@ void intel_increase_renderclock(struct drm_device *dev, bool schedule)
> >  	DRM_DEBUG("increasing render clock frequency\n");
> >  
> >  	/* Schedule downclock */
> > +schedule_timer:
> >  	if (schedule)
> >  		mod_timer(&dev_priv->idle_timer, jiffies +
> >  			  msecs_to_jiffies(GPU_IDLE_TIMEOUT));
> > @@ -3700,6 +3716,11 @@ void intel_decrease_renderclock(struct drm_device *dev)
> >  	if (IS_IGDNG(dev))
> >  		return;
> >  
> > +	if (IS_I945GM(dev)) {
> > +		DRM_DEBUG("enable memory self refresh on 945\n");
> > +		I915_WRITE(FW_BLC_SELF, FW_BLC_SELF_EN_MASK | FW_BLC_SELF_EN);
> > +	}
> > +
> >  	if (!dev_priv->render_reclock_avail) {
> >  		DRM_DEBUG("not reclocking render clock\n");
> >  		return;
> >   
>