linux-kernel - Re: [PATCH v3 3/6] EDAC/fsl_ddr: Fix bad bit shift operations

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Message-ID: <20241022161642.GJZxfP6kbzHPahW3oe@fat_crate.local>
Date: Tue, 22 Oct 2024 18:16:42 +0200
From: Borislav Petkov <bp@...en8.de>
To: Frank Li <Frank.li@....com>
Cc: York Sun <york.sun@....com>, Tony Luck <tony.luck@...el.com>,
	James Morse <james.morse@....com>,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	Robert Richter <rric@...nel.org>,
	Krzysztof Kozlowski <krzk@...nel.org>,
	Rob Herring <robh@...nel.org>, Conor Dooley <conor+dt@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Shawn Guo <shawnguo@...nel.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Pengutronix Kernel Team <kernel@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>, linux-edac@...r.kernel.org,
	linux-kernel@...r.kernel.org, Borislav Petkov <bp@...e.de>,
	devicetree@...r.kernel.org, imx@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org,
	Priyanka Singh <priyanka.singh@....com>,
	Sherry Sun <sherry.sun@....com>, Li Yang <leoyang.li@....com>
Subject: Re: [PATCH v3 3/6] EDAC/fsl_ddr: Fix bad bit shift operations

On Tue, Oct 22, 2024 at 11:29:03AM -0400, Frank Li wrote:
> > You can't keep Reviewed-by tags when you change a patch considerably: Documentation/process/submitting-patches.rst
> 
> Sorry, I omitted it since it is nxp internal reviewer. Do I need repost
> it?

No, I can zap it.

> > > Signed-off-by: Li Yang <leoyang.li@....com>
> >
> > What does that SOB tag mean?
> 
> It is original nxp layerscape platform maintainer. He leave NXP recently
> and some item in MAINTANERS already been removed. It intents to fix
> layerscape platform problem at beginning. And orginal patch have his SOB.
> So I kept as original one.

Ok.

You forgot to comment on this part:

> > >= 0 implies != -1, right?
> >
> > IOW?
> >
> > diff --git a/drivers/edac/fsl_ddr_edac.c b/drivers/edac/fsl_ddr_edac.c
> > index 846a4ba25342..fe822cb9b562 100644
> > --- a/drivers/edac/fsl_ddr_edac.c
> > +++ b/drivers/edac/fsl_ddr_edac.c
> > @@ -328,24 +328,21 @@ static void fsl_mc_check(struct mem_ctl_info *mci)
> >  	 * TODO: Add support for 32-bit wide buses
> >  	 */
> >  	if ((err_detect & DDR_EDE_SBE) && (bus_width == 64)) {
> > -		u64 cap = (u64)cap_high << 32 | (u64)cap_low;
> > +		u64 cap = (u64)cap_high << 32 | cap_low;
> >  		u32 s = syndrome;
> >
> >  		sbe_ecc_decode(cap_high, cap_low, syndrome,
> >  				&bad_data_bit, &bad_ecc_bit);
> >
> > -		if (bad_data_bit != -1)
> > -			fsl_mc_printk(mci, KERN_ERR,
> > -				"Faulty Data bit: %d\n", bad_data_bit);
> > -		if (bad_ecc_bit != -1)
> > -			fsl_mc_printk(mci, KERN_ERR,
> > -				"Faulty ECC bit: %d\n", bad_ecc_bit);
> > -
> > -		if (bad_data_bit >= 0)
> > +		if (bad_data_bit >= 0) {
> > +			fsl_mc_printk(mci, KERN_ERR, "Faulty Data bit: %d\n", bad_data_bit);
> >  			cap ^= 1ULL << bad_data_bit;
> > +		}
> >
> > -		if (bad_ecc_bit >= 0)
> > +		if (bad_ecc_bit >= 0) {
> > +			fsl_mc_printk(mci, KERN_ERR, "Faulty ECC bit: %d\n", bad_ecc_bit);
> >  			s ^= 1 << bad_ecc_bit;
> > +		}
> >
> >  		fsl_mc_printk(mci, KERN_ERR,
> >  			"Expected Data / ECC:\t%#8.8x_%08x / %#2.2x\n",
> >

-- 
Regards/Gruss,
    Boris.

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