Re: [PATCH v9 7/7] drm/i915/tgl: Add DC3CO counter in i915_dmc_info

[Anshuman Gupta <anshuman.gupta@intel.com>]

On 2019-09-27 at 19:38:49 +0300, Imre Deak wrote:
> On Thu, Sep 26, 2019 at 08:26:21PM +0530, Anshuman Gupta wrote:
> > Adding DC3CO counter in i915_dmc_info debugfs will be
> > useful for DC3CO validation.
> > DMC firmware uses DMC_DEBUG3 register as DC3CO counter
> > register on TGL, as per B.Specs DMC_DEBUG3 is general
> > purpose register.
> > 
> > Cc: Jani Nikula <jani.nikula@intel.com>
> > Cc: Imre Deak <imre.deak@intel.com>
> > Cc: Animesh Manna <animesh.manna@intel.com>
> > Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_debugfs.c | 6 ++++++
> >  drivers/gpu/drm/i915/i915_reg.h     | 2 ++
> >  2 files changed, 8 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> > index b5b449a88cf1..8a16bbd31212 100644
> > --- a/drivers/gpu/drm/i915/i915_debugfs.c
> > +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> > @@ -2407,6 +2407,12 @@ static int i915_dmc_info(struct seq_file *m, void *unused)
> >  	seq_printf(m, "version: %d.%d\n", CSR_VERSION_MAJOR(csr->version),
> >  		   CSR_VERSION_MINOR(csr->version));
> >  
> > +	/*
> > +	 * TGL DMC f/w uses DMC_DEBUG3 register for DC3CO counter.
> > +	 */
> 
> The above is obvious from the code itself, so we don't need a comment
> for it. Please also consider removing all other comments in the patchset
> that state only what is obvious from the code.
DMC_DEBUG3 is a DMC general purpose register, B.Specs doesn't specify
it as DC3CO counter unlike DC5 and DC6, that is why i have added
this comment. Shall i remove this comment considering DMC_DEBUG3 
as general purpose register?
> 
> > +	if (IS_TIGERLAKE(dev_priv))
> 
> The above should match the check in get_allowed_dc_mask().
IS_TIGERLAKE is being checked for the same reason as TGL
DMC is using DMC_DEBUG3 for DC3CO counter. It may not be true
for other Gen12 platfrom.
Thanks,
Anshuman Gupta.  
> 
> > +		seq_printf(m, "DC3CO count: %d\n", I915_READ(DMC_DEBUG3));
> > +
> >  	if (INTEL_GEN(dev_priv) >= 12) {
> >  		dc5_reg = TGL_DMC_DEBUG_DC5_COUNT;
> >  		dc6_reg = TGL_DMC_DEBUG_DC6_COUNT;
> > diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> > index 3ee9720af207..af810f6ed652 100644
> > --- a/drivers/gpu/drm/i915/i915_reg.h
> > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > @@ -7263,6 +7263,8 @@ enum {
> >  #define TGL_DMC_DEBUG_DC5_COUNT	_MMIO(0x101084)
> >  #define TGL_DMC_DEBUG_DC6_COUNT	_MMIO(0x101088)
> >  
> > +#define DMC_DEBUG3		_MMIO(0x101090)
> > +
> >  /* interrupts */
> >  #define DE_MASTER_IRQ_CONTROL   (1 << 31)
> >  #define DE_SPRITEB_FLIP_DONE    (1 << 29)
> > -- 
> > 2.21.0
> > 
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