Re: [PATCH] drm/i915/icl: Fix MG_DP_MODE() register programming

[Imre Deak <imre.deak@intel.com>]

On Fri, Apr 19, 2019 at 07:29:05PM +0300, Souza, Jose wrote:
> On Fri, 2019-04-19 at 19:04 +0300, Imre Deak wrote:
> > On Fri, Apr 19, 2019 at 07:02:10PM +0300, Souza, Jose wrote:
> > > On Fri, 2019-04-19 at 10:10 +0300, Imre Deak wrote:
> > > > Fix the order of lane, port parameters passed to the register
> > > > macro.
> > > > 
> > > > Note that this was already partly fixed by commit
> > > > 37fc7845df7b6 ("drm/i915: Call MG_DP_MODE() macro with the right
> > > > parameters order")
> > > > 
> > > > Fixes: 58106b7d816e1 ("drm/i915: Make MG PHY macros semantically
> > > > consistent")
> > > > Cc: José Roberto de Souza <jose.souza@intel.com>
> > > > Cc: Lucas De Marchi <lucas.demarchi@intel.com>
> > > > Cc: Aditya Swarup <aditya.swarup@intel.com>
> > > > Signed-off-by: Imre Deak <imre.deak@intel.com>
> > > > ---
> > > >  drivers/gpu/drm/i915/intel_ddi.c | 18 ++++++++----------
> > > >  1 file changed, 8 insertions(+), 10 deletions(-)
> > > > 
> > > > diff --git a/drivers/gpu/drm/i915/intel_ddi.c
> > > > b/drivers/gpu/drm/i915/intel_ddi.c
> > > > index 24f9106efcc6..f181c26f62fd 100644
> > > > --- a/drivers/gpu/drm/i915/intel_ddi.c
> > > > +++ b/drivers/gpu/drm/i915/intel_ddi.c
> > > > @@ -2905,21 +2905,20 @@ static void
> > > > icl_enable_phy_clock_gating(struct intel_digital_port *dig_port)
> > > >  	struct drm_i915_private *dev_priv = to_i915(dig_port-
> > > > > base.base.dev);
> > > >  	enum port port = dig_port->base.port;
> > > >  	enum tc_port tc_port = intel_port_to_tc(dev_priv, port);
> > > > -	i915_reg_t mg_regs[2] = { MG_DP_MODE(0, port), MG_DP_MODE(1,
> > > > port) };
> > > >  	u32 val;
> > > > -	int i;
> > > > +	int ln;
> > > >  
> > > >  	if (tc_port == PORT_TC_NONE)
> > > >  		return;
> > > >  
> > > > -	for (i = 0; i < ARRAY_SIZE(mg_regs); i++) {
> > > > -		val = I915_READ(mg_regs[i]);
> > > > +	for (ln = 0; ln < 2; ln++) {
> > > > +		val = I915_READ(MG_DP_MODE(ln, port));
> > > >  		val |= MG_DP_MODE_CFG_TR2PWR_GATING |
> > > >  		       MG_DP_MODE_CFG_TRPWR_GATING |
> > > >  		       MG_DP_MODE_CFG_CLNPWR_GATING |
> > > >  		       MG_DP_MODE_CFG_DIGPWR_GATING |
> > > >  		       MG_DP_MODE_CFG_GAONPWR_GATING;
> > > > -		I915_WRITE(mg_regs[i], val);
> > > > +		I915_WRITE(MG_DP_MODE(ln, port), val);
> > > >  	}
> > > >  
> > > >  	val = I915_READ(MG_MISC_SUS0(tc_port));
> > > > @@ -2938,21 +2937,20 @@ static void
> > > > icl_disable_phy_clock_gating(struct intel_digital_port *dig_port)
> > > >  	struct drm_i915_private *dev_priv = to_i915(dig_port-
> > > > > base.base.dev);
> > > >  	enum port port = dig_port->base.port;
> > > >  	enum tc_port tc_port = intel_port_to_tc(dev_priv, port);
> > > > -	i915_reg_t mg_regs[2] = { MG_DP_MODE(port, 0), MG_DP_MODE(port,
> > > > 1) };
> > > 
> > > I would split this fix from the change dropping mg_regs or at least
> > > tell that while you were fixing it you changed the way it reads
> > > each MG_DP_MODE line.
> > 
> > I don't think it's worth a separate patch, since it's a small change
> > and quite obvious what and how changed. I can add a note to the
> > commit
> > message about making things simpler.
> 
> I suggested split because this will probably be backported so would be
> nice to be as clean as possible but I'm also okay if you add it to the
> commit description.

No need to backport this, the regressing commit won't make it to 5.1.
Even if it had this fix would still go through -fixes since we're still
only in -rc5, and so we wouldn't need to backport anything. So this
change along with the rest of related macro param shuffling patches
won't appear until 5.2.

For the future: git fetch stable; git fetch linus-upstream followed by
git tag --contains <regressing commit> makes it easy to see if something
needs backporting.

> 
> > 
> > > 
> > > >  	u32 val;
> > > > -	int i;
> > > > +	int ln;
> > > >  
> > > >  	if (tc_port == PORT_TC_NONE)
> > > >  		return;
> > > >  
> > > > -	for (i = 0; i < ARRAY_SIZE(mg_regs); i++) {
> > > > -		val = I915_READ(mg_regs[i]);
> > > > +	for (ln = 0; ln < 2; ln++) {
> > > > +		val = I915_READ(MG_DP_MODE(ln, port));
> > > >  		val &= ~(MG_DP_MODE_CFG_TR2PWR_GATING |
> > > >  			 MG_DP_MODE_CFG_TRPWR_GATING |
> > > >  			 MG_DP_MODE_CFG_CLNPWR_GATING |
> > > >  			 MG_DP_MODE_CFG_DIGPWR_GATING |
> > > >  			 MG_DP_MODE_CFG_GAONPWR_GATING);
> > > > -		I915_WRITE(mg_regs[i], val);
> > > > +		I915_WRITE(MG_DP_MODE(ln, port), val);
> > > >  	}
> > > >  
> > > >  	val = I915_READ(MG_MISC_SUS0(tc_port));
> > 
> > 


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