Re: [PATCH] drm/i915: Correct the IOSF Dev_FN field for IOSF transfers

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, Feb 05, 2015 at 05:10:56PM +0530, Shobhit Kumar wrote:
> As per the specififcation, the SB_DevFn is the PCI_DEVFN of the target
> device and not the source. So PCI_DEVFN(2,0) is not correct. Further the
> port ID should be enough to identify devices unless they are MFD. The
> SB_DevFn was intended to remove ambiguity in case of these MFD devices.
> 
> For non MFD devices the recommendation for the target device IP was to
> ignore these fields, but not all of them followed the recommendation.
> Some like CCK ignore these fields and hence PCI_DEVFN(2, 0) works and so
> does PCI_DEVFN(0, 0) as it works for DPIO. The issue came to light because
> of GPIONC which was not getting programmed correctly with PCI_DEVFN(2, 0).
> It turned out that this did not follow the recommendation and expected 0
> in this field.
> 
> In general the recommendation is to use SB_DevFn as PCI_DEVFN(0, 0) for
> all devices except target PCI devices.
> 
> Signed-off-by: Shobhit Kumar <shobhit.kumar@intel.com>

Yep, confirmed on my BYT that GPIONC doesn't like the devfn 2.0. On BSW
GPIONC seems to have become more relaxed and accepts devfn 2.0 as well.

I also tried to poke at all the other sideband units we care about and
they appear to work just as well with 2.0 and 0.0. But being consistent
seems like a good idea, so 0.0 it is for everyone.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> ---
>  drivers/gpu/drm/i915/intel_sideband.c | 26 +++++++++++++-------------
>  1 file changed, 13 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_sideband.c b/drivers/gpu/drm/i915/intel_sideband.c
> index 01d841e..731b10a 100644
> --- a/drivers/gpu/drm/i915/intel_sideband.c
> +++ b/drivers/gpu/drm/i915/intel_sideband.c
> @@ -82,7 +82,7 @@ u32 vlv_punit_read(struct drm_i915_private *dev_priv, u8 addr)
>  	WARN_ON(!mutex_is_locked(&dev_priv->rps.hw_lock));
>  
>  	mutex_lock(&dev_priv->dpio_lock);
> -	vlv_sideband_rw(dev_priv, PCI_DEVFN(2, 0), IOSF_PORT_PUNIT,
> +	vlv_sideband_rw(dev_priv, PCI_DEVFN(0, 0), IOSF_PORT_PUNIT,
>  			SB_CRRDDA_NP, addr, &val);
>  	mutex_unlock(&dev_priv->dpio_lock);
>  
> @@ -94,7 +94,7 @@ void vlv_punit_write(struct drm_i915_private *dev_priv, u8 addr, u32 val)
>  	WARN_ON(!mutex_is_locked(&dev_priv->rps.hw_lock));
>  
>  	mutex_lock(&dev_priv->dpio_lock);
> -	vlv_sideband_rw(dev_priv, PCI_DEVFN(2, 0), IOSF_PORT_PUNIT,
> +	vlv_sideband_rw(dev_priv, PCI_DEVFN(0, 0), IOSF_PORT_PUNIT,
>  			SB_CRWRDA_NP, addr, &val);
>  	mutex_unlock(&dev_priv->dpio_lock);
>  }
> @@ -103,7 +103,7 @@ u32 vlv_bunit_read(struct drm_i915_private *dev_priv, u32 reg)
>  {
>  	u32 val = 0;
>  
> -	vlv_sideband_rw(dev_priv, PCI_DEVFN(2, 0), IOSF_PORT_BUNIT,
> +	vlv_sideband_rw(dev_priv, PCI_DEVFN(0, 0), IOSF_PORT_BUNIT,
>  			SB_CRRDDA_NP, reg, &val);
>  
>  	return val;
> @@ -111,7 +111,7 @@ u32 vlv_bunit_read(struct drm_i915_private *dev_priv, u32 reg)
>  
>  void vlv_bunit_write(struct drm_i915_private *dev_priv, u32 reg, u32 val)
>  {
> -	vlv_sideband_rw(dev_priv, PCI_DEVFN(2, 0), IOSF_PORT_BUNIT,
> +	vlv_sideband_rw(dev_priv, PCI_DEVFN(0, 0), IOSF_PORT_BUNIT,
>  			SB_CRWRDA_NP, reg, &val);
>  }
>  
> @@ -122,7 +122,7 @@ u32 vlv_nc_read(struct drm_i915_private *dev_priv, u8 addr)
>  	WARN_ON(!mutex_is_locked(&dev_priv->rps.hw_lock));
>  
>  	mutex_lock(&dev_priv->dpio_lock);
> -	vlv_sideband_rw(dev_priv, PCI_DEVFN(2, 0), IOSF_PORT_NC,
> +	vlv_sideband_rw(dev_priv, PCI_DEVFN(0, 0), IOSF_PORT_NC,
>  			SB_CRRDDA_NP, addr, &val);
>  	mutex_unlock(&dev_priv->dpio_lock);
>  
> @@ -132,56 +132,56 @@ u32 vlv_nc_read(struct drm_i915_private *dev_priv, u8 addr)
>  u32 vlv_gpio_nc_read(struct drm_i915_private *dev_priv, u32 reg)
>  {
>  	u32 val = 0;
> -	vlv_sideband_rw(dev_priv, PCI_DEVFN(2, 0), IOSF_PORT_GPIO_NC,
> +	vlv_sideband_rw(dev_priv, PCI_DEVFN(0, 0), IOSF_PORT_GPIO_NC,
>  			SB_CRRDDA_NP, reg, &val);
>  	return val;
>  }
>  
>  void vlv_gpio_nc_write(struct drm_i915_private *dev_priv, u32 reg, u32 val)
>  {
> -	vlv_sideband_rw(dev_priv, PCI_DEVFN(2, 0), IOSF_PORT_GPIO_NC,
> +	vlv_sideband_rw(dev_priv, PCI_DEVFN(0, 0), IOSF_PORT_GPIO_NC,
>  			SB_CRWRDA_NP, reg, &val);
>  }
>  
>  u32 vlv_cck_read(struct drm_i915_private *dev_priv, u32 reg)
>  {
>  	u32 val = 0;
> -	vlv_sideband_rw(dev_priv, PCI_DEVFN(2, 0), IOSF_PORT_CCK,
> +	vlv_sideband_rw(dev_priv, PCI_DEVFN(0, 0), IOSF_PORT_CCK,
>  			SB_CRRDDA_NP, reg, &val);
>  	return val;
>  }
>  
>  void vlv_cck_write(struct drm_i915_private *dev_priv, u32 reg, u32 val)
>  {
> -	vlv_sideband_rw(dev_priv, PCI_DEVFN(2, 0), IOSF_PORT_CCK,
> +	vlv_sideband_rw(dev_priv, PCI_DEVFN(0, 0), IOSF_PORT_CCK,
>  			SB_CRWRDA_NP, reg, &val);
>  }
>  
>  u32 vlv_ccu_read(struct drm_i915_private *dev_priv, u32 reg)
>  {
>  	u32 val = 0;
> -	vlv_sideband_rw(dev_priv, PCI_DEVFN(2, 0), IOSF_PORT_CCU,
> +	vlv_sideband_rw(dev_priv, PCI_DEVFN(0, 0), IOSF_PORT_CCU,
>  			SB_CRRDDA_NP, reg, &val);
>  	return val;
>  }
>  
>  void vlv_ccu_write(struct drm_i915_private *dev_priv, u32 reg, u32 val)
>  {
> -	vlv_sideband_rw(dev_priv, PCI_DEVFN(2, 0), IOSF_PORT_CCU,
> +	vlv_sideband_rw(dev_priv, PCI_DEVFN(0, 0), IOSF_PORT_CCU,
>  			SB_CRWRDA_NP, reg, &val);
>  }
>  
>  u32 vlv_gps_core_read(struct drm_i915_private *dev_priv, u32 reg)
>  {
>  	u32 val = 0;
> -	vlv_sideband_rw(dev_priv, PCI_DEVFN(2, 0), IOSF_PORT_GPS_CORE,
> +	vlv_sideband_rw(dev_priv, PCI_DEVFN(0, 0), IOSF_PORT_GPS_CORE,
>  			SB_CRRDDA_NP, reg, &val);
>  	return val;
>  }
>  
>  void vlv_gps_core_write(struct drm_i915_private *dev_priv, u32 reg, u32 val)
>  {
> -	vlv_sideband_rw(dev_priv, PCI_DEVFN(2, 0), IOSF_PORT_GPS_CORE,
> +	vlv_sideband_rw(dev_priv, PCI_DEVFN(0, 0), IOSF_PORT_GPS_CORE,
>  			SB_CRWRDA_NP, reg, &val);
>  }
>  
> -- 
> 1.9.1

-- 
Ville Syrjälä
Intel OTC
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