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

[Shobhit Kumar <shobhit.kumar@linux.intel.com>]

On 02/06/2015 02:20 PM, Jani Nikula wrote:
> On Thu, 05 Feb 2015, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote:
>> 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.
> 
> Shobhit, do you have any idea if there are devices out there that would
> really need this, i.e. should we backport this to stable kernels or is
> it good enough for next?

For sure the Asus T100 does not need any sequence and so does not need
this patch also. But I think there are other devices which might need.
Till now I figured out only GPIONC and GPS as two targets misbehaving.
If GPIONC is needed in sequences of those other devices in market, they
will get impacted.

Regards
Shobhit

> 
> BR,
> Jani.
> 
> 
>>
>> 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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