Re: [PATCH 7/7] drm/i915: Take punit lock when modifying punit settings

[Hans de Goede <hdegoede@xxxxxxxxxx>]

Hi,

On 08-01-17 16:34, Andy Shevchenko wrote:
> On Sun, 2017-01-08 at 14:44 +0100, Hans de Goede wrote:
> > Make sure the punit i2c bus is not in use when we send a request to
> > the punit by calling iosf_mbi_punit_lock() / iosf_mbi_punit_unlock()
> > around punit write accesses.
>
> But should not i915 drm eventually share the same iosf_mbi driver?
> Currently what you are doing you create notifier and all that not-best-
> ever stuff due to having two accessors to IOSF MB. If we have only one
> driver which i915 will not ignore you don't need to create such things.
>
> That's what I was trying to imply when commenting one of the patch in
> previous series.

Ah, yes that as an interesting point. So what do the i915 devs think
of changing the i915 code to use the iosf_mbi functions for at least
punit accesses, instead of doing those through the i915 pci config space?

Note that we will still need to have some higher level locking, or
a new iosf_mbi function which does this under a lock, for code paths
where the i915 code does a write followed by multiple reads to wait
for the punit to have changed the value to the requested value.

Regards,

Hans




> > BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=155241
> > Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> > Tested-by: tagorereddy <tagore.chandan@xxxxxxxxx>
> > ---
> >  drivers/gpu/drm/i915/intel_display.c    | 6 ++++++
> >  drivers/gpu/drm/i915/intel_pm.c         | 9 +++++++++
> >  drivers/gpu/drm/i915/intel_runtime_pm.c | 9 +++++++++
> >  3 files changed, 24 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_display.c
> > b/drivers/gpu/drm/i915/intel_display.c
> > index fec8eb3..b8be6ea 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -47,6 +47,7 @@
> >  #include <drm/drm_rect.h>
> >  #include <linux/dma_remapping.h>
> >  #include <linux/reservation.h>
> > +#include <asm/iosf_mbi.h>
> >
> >  static bool is_mmio_work(struct intel_flip_work *work)
> >  {
> > @@ -6423,6 +6424,8 @@ static void valleyview_set_cdclk(struct
> > drm_device *dev, int cdclk)
> >  		cmd = 0;
> >
> >  	mutex_lock(&dev_priv->rps.hw_lock);
> > +	iosf_mbi_punit_lock();
> > +
> >  	val = vlv_punit_read(dev_priv, PUNIT_REG_DSPFREQ);
> >  	val &= ~DSPFREQGUAR_MASK;
> >  	val |= (cmd << DSPFREQGUAR_SHIFT);
> > @@ -6432,6 +6435,7 @@ static void valleyview_set_cdclk(struct
> > drm_device *dev, int cdclk)
> >  		     50)) {
> >  		DRM_ERROR("timed out waiting for CDclk change\n");
> >  	}
> > +	iosf_mbi_punit_unlock();
> >  	mutex_unlock(&dev_priv->rps.hw_lock);
> >
> >  	mutex_lock(&dev_priv->sb_lock);
> > @@ -6499,6 +6503,7 @@ static void cherryview_set_cdclk(struct
> > drm_device *dev, int cdclk)
> >  	cmd = DIV_ROUND_CLOSEST(dev_priv->hpll_freq << 1, cdclk) - 1;
> >
> >  	mutex_lock(&dev_priv->rps.hw_lock);
> > +	iosf_mbi_punit_lock();
> >  	val = vlv_punit_read(dev_priv, PUNIT_REG_DSPFREQ);
> >  	val &= ~DSPFREQGUAR_MASK_CHV;
> >  	val |= (cmd << DSPFREQGUAR_SHIFT_CHV);
> > @@ -6508,6 +6513,7 @@ static void cherryview_set_cdclk(struct
> > drm_device *dev, int cdclk)
> >  		     50)) {
> >  		DRM_ERROR("timed out waiting for CDclk change\n");
> >  	}
> > +	iosf_mbi_punit_unlock();
> >  	mutex_unlock(&dev_priv->rps.hw_lock);
> >
> >  	intel_update_cdclk(dev_priv);
> > diff --git a/drivers/gpu/drm/i915/intel_pm.c
> > b/drivers/gpu/drm/i915/intel_pm.c
> > index 4b12637..0d55b61 100644
> > --- a/drivers/gpu/drm/i915/intel_pm.c
> > +++ b/drivers/gpu/drm/i915/intel_pm.c
> > @@ -32,6 +32,7 @@
> >  #include "../../../platform/x86/intel_ips.h"
> >  #include <linux/module.h>
> >  #include <drm/drm_atomic_helper.h>
> > +#include <asm/iosf_mbi.h>
> >
> >  /**
> >   * DOC: RC6
> > @@ -276,6 +277,7 @@ static void chv_set_memory_dvfs(struct
> > drm_i915_private *dev_priv, bool enable)
> >  	u32 val;
> >
> >  	mutex_lock(&dev_priv->rps.hw_lock);
> > +	iosf_mbi_punit_lock();
> >
> >  	val = vlv_punit_read(dev_priv, PUNIT_REG_DDR_SETUP2);
> >  	if (enable)
> > @@ -290,6 +292,7 @@ static void chv_set_memory_dvfs(struct
> > drm_i915_private *dev_priv, bool enable)
> >  		      FORCE_DDR_FREQ_REQ_ACK) == 0, 3))
> >  		DRM_ERROR("timed out waiting for Punit DDR DVFS
> > request\n");
> >
> > +	iosf_mbi_punit_unlock();
> >  	mutex_unlock(&dev_priv->rps.hw_lock);
> >  }
> >
> > @@ -298,6 +301,7 @@ static void chv_set_memory_pm5(struct
> > drm_i915_private *dev_priv, bool enable)
> >  	u32 val;
> >
> >  	mutex_lock(&dev_priv->rps.hw_lock);
> > +	iosf_mbi_punit_lock();
> >
> >  	val = vlv_punit_read(dev_priv, PUNIT_REG_DSPFREQ);
> >  	if (enable)
> > @@ -306,6 +310,7 @@ static void chv_set_memory_pm5(struct
> > drm_i915_private *dev_priv, bool enable)
> >  		val &= ~DSP_MAXFIFO_PM5_ENABLE;
> >  	vlv_punit_write(dev_priv, PUNIT_REG_DSPFREQ, val);
> >
> > +	iosf_mbi_punit_unlock();
> >  	mutex_unlock(&dev_priv->rps.hw_lock);
> >  }
> >
> > @@ -4546,6 +4551,7 @@ void vlv_wm_get_hw_state(struct drm_device *dev)
> >
> >  	if (IS_CHERRYVIEW(dev_priv)) {
> >  		mutex_lock(&dev_priv->rps.hw_lock);
> > +		iosf_mbi_punit_lock();
> >
> >  		val = vlv_punit_read(dev_priv, PUNIT_REG_DSPFREQ);
> >  		if (val & DSP_MAXFIFO_PM5_ENABLE)
> > @@ -4575,6 +4581,7 @@ void vlv_wm_get_hw_state(struct drm_device *dev)
> >  				wm->level = VLV_WM_LEVEL_DDR_DVFS;
> >  		}
> >
> > +		iosf_mbi_punit_unlock();
> >  		mutex_unlock(&dev_priv->rps.hw_lock);
> >  	}
> >
> > @@ -4981,7 +4988,9 @@ static void valleyview_set_rps(struct
> > drm_i915_private *dev_priv, u8 val)
> >  	I915_WRITE(GEN6_PMINTRMSK, gen6_rps_pm_mask(dev_priv, val));
> >
> >  	if (val != dev_priv->rps.cur_freq) {
> > +		iosf_mbi_punit_lock();
> >  		vlv_punit_write(dev_priv, PUNIT_REG_GPU_FREQ_REQ,
> > val);
> > +		iosf_mbi_punit_unlock();
> >  		if (!IS_CHERRYVIEW(dev_priv))
> >  			gen6_set_rps_thresholds(dev_priv, val);
> >  	}
> > diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c
> > b/drivers/gpu/drm/i915/intel_runtime_pm.c
> > index c0b7e95..17922ae 100644
> > --- a/drivers/gpu/drm/i915/intel_runtime_pm.c
> > +++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
> > @@ -28,6 +28,7 @@
> >
> >  #include <linux/pm_runtime.h>
> >  #include <linux/vgaarb.h>
> > +#include <asm/iosf_mbi.h>
> >
> >  #include "i915_drv.h"
> >  #include "intel_drv.h"
> > @@ -1027,6 +1028,8 @@ static void vlv_set_power_well(struct
> > drm_i915_private *dev_priv,
> >  	if (COND)
> >  		goto out;
> >
> > +	iosf_mbi_punit_lock();
> > +
> >  	ctrl = vlv_punit_read(dev_priv, PUNIT_REG_PWRGT_CTRL);
> >  	ctrl &= ~mask;
> >  	ctrl |= state;
> > @@ -1037,6 +1040,8 @@ static void vlv_set_power_well(struct
> > drm_i915_private *dev_priv,
> >  			  state,
> >  			  vlv_punit_read(dev_priv,
> > PUNIT_REG_PWRGT_CTRL));
> >
> > +	iosf_mbi_punit_unlock();
> > +
> >  #undef COND
> >
> >  out:
> > @@ -1643,6 +1648,8 @@ static void chv_set_pipe_power_well(struct
> > drm_i915_private *dev_priv,
> >  	if (COND)
> >  		goto out;
> >
> > +	iosf_mbi_punit_lock();
> > +
> >  	ctrl = vlv_punit_read(dev_priv, PUNIT_REG_DSPFREQ);
> >  	ctrl &= ~DP_SSC_MASK(pipe);
> >  	ctrl |= enable ? DP_SSC_PWR_ON(pipe) : DP_SSC_PWR_GATE(pipe);
> > @@ -1653,6 +1660,8 @@ static void chv_set_pipe_power_well(struct
> > drm_i915_private *dev_priv,
> >  			  state,
> >  			  vlv_punit_read(dev_priv,
> > PUNIT_REG_DSPFREQ));
> >
> > +	iosf_mbi_punit_unlock();
> > +
> >  #undef COND
> >
> >  out:
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