Re: [Intel-gfx] [PATCH 05/13] drm/i915/psr: Bring back HSW/BDW PSR AUX CH registers/setup

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

On Fri, Apr 28, 2023 at 10:18:34AM +0000, Hogander, Jouni wrote:
> Hello,
> 
> Please check my inline comments below.
> 
> On Fri, 2023-04-21 at 15:02 +0300, Ville Syrjala wrote:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > 
> > Reintroduce the special PSR AUX CH setup for hsw/bdw. Not all
> > of it was even removed (BDW AUX data registers were left behind).
> > Update the code to use REG_BIT() & co. while at it.
> > 
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_dp_aux.c   |  2 +-
> >  drivers/gpu/drm/i915/display/intel_dp_aux.h   |  4 ++
> >  drivers/gpu/drm/i915/display/intel_psr.c      | 61
> > +++++++++++++++++++
> >  drivers/gpu/drm/i915/display/intel_psr_regs.h | 11 ++++
> >  4 files changed, 77 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux.c
> > b/drivers/gpu/drm/i915/display/intel_dp_aux.c
> > index abf77ba76972..847fd6bfa7e4 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp_aux.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp_aux.c
> > @@ -14,7 +14,7 @@
> >  #include "intel_pps.h"
> >  #include "intel_tc.h"
> >  
> > -static u32 intel_dp_aux_pack(const u8 *src, int src_bytes)
> > +u32 intel_dp_aux_pack(const u8 *src, int src_bytes)
> >  {
> >         int i;
> >         u32 v = 0;
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux.h
> > b/drivers/gpu/drm/i915/display/intel_dp_aux.h
> > index 138e340f94ee..3bc529a23dd6 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp_aux.h
> > +++ b/drivers/gpu/drm/i915/display/intel_dp_aux.h
> > @@ -6,6 +6,8 @@
> >  #ifndef __INTEL_DP_AUX_H__
> >  #define __INTEL_DP_AUX_H__
> >  
> > +#include <linux/types.h>
> > +
> >  enum aux_ch;
> >  struct intel_dp;
> >  struct intel_encoder;
> > @@ -15,4 +17,6 @@ void intel_dp_aux_init(struct intel_dp *intel_dp);
> >  
> >  enum aux_ch intel_dp_aux_ch(struct intel_encoder *encoder);
> >  
> > +u32 intel_dp_aux_pack(const u8 *src, int src_bytes);
> > +
> >  #endif /* __INTEL_DP_AUX_H__ */
> > diff --git a/drivers/gpu/drm/i915/display/intel_psr.c
> > b/drivers/gpu/drm/i915/display/intel_psr.c
> > index 7f748c7a71f3..2ff6f75c2bee 100644
> > --- a/drivers/gpu/drm/i915/display/intel_psr.c
> > +++ b/drivers/gpu/drm/i915/display/intel_psr.c
> > @@ -288,6 +288,24 @@ static i915_reg_t psr_iir_reg(struct
> > drm_i915_private *dev_priv,
> >                 return EDP_PSR_IIR;
> >  }
> >  
> > +static i915_reg_t psr_aux_ctl_reg(struct drm_i915_private *dev_priv,
> > +                                 enum transcoder cpu_transcoder)
> > +{
> > +       if (DISPLAY_VER(dev_priv) >= 8)
> > +               return EDP_PSR_AUX_CTL(cpu_transcoder);
> > +       else
> > +               return HSW_SRD_AUX_CTL;
> > +}
> > +
> > +static i915_reg_t psr_aux_data_reg(struct drm_i915_private
> > *dev_priv,
> > +                                  enum transcoder cpu_transcoder,
> > int i)
> > +{
> > +       if (DISPLAY_VER(dev_priv) >= 8)
> > +               return EDP_PSR_AUX_DATA(cpu_transcoder, i);
> > +       else
> > +               return HSW_SRD_AUX_DATA(i);
> > +}
> > +
> >  static void psr_irq_control(struct intel_dp *intel_dp)
> >  {
> >         struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
> > @@ -512,6 +530,42 @@ void intel_psr_init_dpcd(struct intel_dp
> > *intel_dp)
> >         }
> >  }
> >  
> > +static void hsw_psr_setup_aux(struct intel_dp *intel_dp)
> > +{
> > +       struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
> > +       enum transcoder cpu_transcoder = intel_dp->psr.transcoder;
> > +       u32 aux_clock_divider, aux_ctl;
> > +       static const u8 aux_msg[] = {
> > +               [0] = (DP_AUX_NATIVE_WRITE << 4) | ((DP_SET_POWER >>
> > 16) & 0xf),
> > +               [1] = (DP_SET_POWER >> 8) & 0xff,
> > +               [2] = DP_SET_POWER & 0xff,
> > +               [3] = 1 - 1,
> > +               [4] = DP_SET_POWER_D0,
> > +       };
> 
> Could you please add some description or provide some pointer which
> would help to parse what you are doing here?

It's just crafting a DP_SET_POWER=D0 DPCD write by hand.

I was thinking of refactoring the AUX msg packing code
to make thig something like
 struct drm_dp_aux_msg {
 	...
 };
 intel_dp_aux_pack_msg(msg)
but that would require some actual though so not something
I want to do in this patch. So for now I just restored
this to (more or less) what we had before.

> 
> > +       int i;
> > +
> > +       BUILD_BUG_ON(sizeof(aux_msg) > 20);
> > +       for (i = 0; i < sizeof(aux_msg); i += 4)
> > +               intel_de_write(dev_priv,
> > +                              psr_aux_data_reg(dev_priv,
> > cpu_transcoder, i >> 2),
> > +                              intel_dp_aux_pack(&aux_msg[i],
> > sizeof(aux_msg) - i));
> > +
> > +       aux_clock_divider = intel_dp->get_aux_clock_divider(intel_dp,
> > 0);
> > +
> > +       /* Start with bits set for DDI_AUX_CTL register */
> > +       aux_ctl = intel_dp->get_aux_send_ctl(intel_dp,
> > sizeof(aux_msg),
> > +                                            aux_clock_divider);
> > +
> > +       /* Select only valid bits for SRD_AUX_CTL */
> > +       aux_ctl &= EDP_PSR_AUX_CTL_TIME_OUT_MASK |
> > +               EDP_PSR_AUX_CTL_MESSAGE_SIZE_MASK |
> > +               EDP_PSR_AUX_CTL_PRECHARGE_2US_MASK |
> > +               EDP_PSR_AUX_CTL_BIT_CLOCK_2X_MASK;
> 
> How about using definitions from
> drivers/gpu/drm/i915/display/intel_dp_aux_regs.h?

I suppose we could define the bits as
 #define EPD_PSR_FOO DP_AUX_CH_CTL_FOO
instead of defining them with REG_BIT() & co. direclty,
to make it clear they are identical.

> Or just refer these
> being identical definitions to aux_send_ctl bits?
> 
> > +
> > +       intel_de_write(dev_priv, psr_aux_ctl_reg(dev_priv,
> > cpu_transcoder),
> > +                      aux_ctl);
> > +}
> > +
> >  static void intel_psr_enable_sink(struct intel_dp *intel_dp)
> >  {
> >         struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
> > @@ -1318,6 +1372,13 @@ static void intel_psr_enable_source(struct
> > intel_dp *intel_dp,
> >         enum transcoder cpu_transcoder = intel_dp->psr.transcoder;
> >         u32 mask;
> >  
> > +       /*
> > +        * Only HSW and BDW have PSR AUX registers that need to be
> > setup.
> > +        * SKL+ use hardcoded values PSR AUX transactions
> > +        */
> > +       if (DISPLAY_VER(dev_priv) < 9)
> > +               hsw_psr_setup_aux(intel_dp);
> > +
> >         /*
> >          * Per Spec: Avoid continuous PSR exit by masking MEMUP and
> > HPD also
> >          * mask LPSP to avoid dependency on other drivers that might
> > block
> > diff --git a/drivers/gpu/drm/i915/display/intel_psr_regs.h
> > b/drivers/gpu/drm/i915/display/intel_psr_regs.h
> > index 998f638ee182..5e54817b6a0f 100644
> > --- a/drivers/gpu/drm/i915/display/intel_psr_regs.h
> > +++ b/drivers/gpu/drm/i915/display/intel_psr_regs.h
> > @@ -80,6 +80,17 @@
> >  #define   EDP_PSR_PRE_ENTRY(trans)     (TGL_PSR_PRE_ENTRY
> > <<           \
> >                                          _EDP_PSR_TRANS_SHIFT(trans))
> >  
> > +#define
> > HSW_SRD_AUX_CTL                                _MMIO(0x64810)
> > +#define _SRD_AUX_CTL_A                         0x60810
> > +#define _SRD_AUX_CTL_EDP                       0x6f810
> > +#define EDP_PSR_AUX_CTL(tran)                  _MMIO_TRANS2(tran,
> > _SRD_AUX_CTL_A)
> > +#define  
> > EDP_PSR_AUX_CTL_TIME_OUT_MASK                REG_GENMASK(27, 26)
> > +#define   EDP_PSR_AUX_CTL_MESSAGE_SIZE_MASK    REG_GENMASK(24, 20)
> > +#define   EDP_PSR_AUX_CTL_PRECHARGE_2US_MASK   REG_GENMASK(19, 16)
> > +#define   EDP_PSR_AUX_CTL_ERROR_INTERRUPT      REG_BIT(11)
> > +#define   EDP_PSR_AUX_CTL_BIT_CLOCK_2X_MASK    REG_GENMASK(10, 0)
> > +
> > +#define HSW_SRD_AUX_DATA(i)                    _MMIO(0x64814 + (i) *
> > 4) /* 5 registers */
> >  #define _SRD_AUX_DATA_A                                0x60814
> >  #define _SRD_AUX_DATA_EDP                      0x6f814
> >  #define EDP_PSR_AUX_DATA(tran, i)              _MMIO_TRANS2(tran,
> > _SRD_AUX_DATA_A + (i) * 4) /* 5 registers */
> 
> BR,
> 
> Jouni Högander
> 

-- 
Ville Syrjälä
Intel