linux-kernel - Re: [PATCH] phy: qcom: qmp: Add debug prints for register writes

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Message-ID: <sqaeseivhysqzzc2udkjv23l5tysjr6hxtlide3an7dngwtdoe@njmgfk3kcvt6>
Date: Wed, 31 Jul 2024 15:19:24 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Vinod Koul <vkoul@...nel.org>
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>, 
	kishon@...nel.org, linux-arm-msm@...r.kernel.org, linux-phy@...ts.infradead.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] phy: qcom: qmp: Add debug prints for register writes

On Wed, Jul 31, 2024 at 03:18:34PM GMT, Dmitry Baryshkov wrote:
> On Wed, Jul 31, 2024 at 04:28:46PM GMT, Vinod Koul wrote:
> > On 30-07-24, 15:33, Manivannan Sadhasivam wrote:
> > > These register prints are useful to validate the init sequence against the
> > > Qcom internal documentation and also to share with the Qcom hw engineers to
> > > debug issues related to PHY.
> > > 
> > > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> > > ---
> > >  drivers/phy/qualcomm/phy-qcom-qmp-common.h | 4 ++++
> > >  1 file changed, 4 insertions(+)
> > > 
> > > diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-common.h b/drivers/phy/qualcomm/phy-qcom-qmp-common.h
> > > index 799384210509..e6a6bcfcac28 100644
> > > --- a/drivers/phy/qualcomm/phy-qcom-qmp-common.h
> > > +++ b/drivers/phy/qualcomm/phy-qcom-qmp-common.h
> > > @@ -9,6 +9,7 @@
> > >  struct qmp_phy_init_tbl {
> > >  	unsigned int offset;
> > >  	unsigned int val;
> > > +	char *name;
> > >  	/*
> > >  	 * mask of lanes for which this register is written
> > >  	 * for cases when second lane needs different values
> > > @@ -20,6 +21,7 @@ struct qmp_phy_init_tbl {
> > >  	{				\
> > >  		.offset = o,		\
> > >  		.val = v,		\
> > > +		.name = #o,		\
> > >  		.lane_mask = 0xff,	\
> > >  	}
> > >  
> > > @@ -27,6 +29,7 @@ struct qmp_phy_init_tbl {
> > >  	{				\
> > >  		.offset = o,		\
> > >  		.val = v,		\
> > > +		.name = #o,		\
> > >  		.lane_mask = l,		\
> > >  	}
> > >  
> > > @@ -45,6 +48,7 @@ static inline void qmp_configure_lane(void __iomem *base,
> > >  		if (!(t->lane_mask & lane_mask))
> > >  			continue;
> > >  
> > > +		pr_debug("QMP PHY: Writing: %s --> 0x%02x\n", t->name, t->val);
> > 
> > This lgtm, but fails to help when offset _might_ be incorrect, including
> > the offset value as well (not just the name) would be better imo... 
> 
> Can we please use dev_vdbg instead? Having dev_ part makes sure that we
> can not mismatch PHYs and the sequences. _vdbg is less important, but
> I don't think we want this in the log messages unless absolutely
> required.
> 
> Also, could you possibly apply this to all other QMP drivers?

Please ignore the last phrase, it is used by all QMP drivers.

-- 
With best wishes
Dmitry