linux-kernel - Re: [RFC PATCH] mtd: lpddr: Fix bad logic in print_drs

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Date:   Mon, 27 Apr 2020 10:33:02 -0700
From:   Joe Perches <joe@...ches.com>
To:     Miquel Raynal <miquel.raynal@...tlin.com>
Cc:     Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        linux-mtd@...ts.infradead.org,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH] mtd: lpddr: Fix bad logic in print_drs_error

On Mon, 2020-04-27 at 15:29 +0200, Miquel Raynal wrote:
> Hi Joe,

Hello Miquel.

> Joe Perches <joe@...ches.com> wrote on Mon, 30 Mar 2020 12:56:59 -0700:
> 
> > Update logic for broken test.
> > Use a more common logging style.
> > 
> > Miscellanea:
> > 
> > o Coalesce formats
> > 
> > Signed-off-by: Joe Perches <joe@...ches.com>
> > ---
> > 
> > Found by inspection of include files using printk.
> > 
> > It appears the logic in this function is broken for the
> > consecutive tests of
> > 
> > 	if (prog_status & 0x3)
> > 		...
> > 	else if (prog_status & 0x2)
> > 		...
> > 	else (prog_status & 0x1)
> > 		...
> > 
> > Likely the first test should be
> > 
> > 	if ((prog_status & 0x3) == 0x3)
> 
> I had a hard time understanding the patch just with the commit log, I
> think the above text is as important.
> 
> In fact, would you mind doing the printk->pr_notice in a first patch,
> and fix the wrong condition in a separate change?
> 
> > And this function is only used in drivers/mtd/lpddr/lpddr_cmds.c
> > perhaps it should be moved there.
> 
> Agreed, do not hesitate to move the function as suggested in a third
> patch.

You are the maintainer here no?

I think you (or perhaps the author Alexey Korolev but he hasn't
been active in a decade) should be doing all this.

I just identified the logic defect.

> >  include/linux/mtd/pfow.h | 31 ++++++++++++++-----------------
> >  1 file changed, 14 insertions(+), 17 deletions(-)
> > 
> > diff --git a/include/linux/mtd/pfow.h b/include/linux/mtd/pfow.h
> > index 122f343..1c08e75 100644
> > --- a/include/linux/mtd/pfow.h
> > +++ b/include/linux/mtd/pfow.h
> > @@ -127,31 +127,28 @@ static inline void print_drs_error(unsigned dsr)
> >  	int prog_status = (dsr & DSR_RPS) >> 8;
> >  
> >  	if (!(dsr & DSR_AVAILABLE))
> > -		printk(KERN_NOTICE"DSR.15: (0) Device not Available\n");
> > -	if (prog_status & 0x03)
> > -		printk(KERN_NOTICE"DSR.9,8: (11) Attempt to program invalid "
> > -						"half with 41h command\n");
> > +		pr_notice("DSR.15: (0) Device not Available\n");
> > +
> > +	if ((prog_status & 0x03) == 0x03)
> > +		pr_notice("DSR.9,8: (11) Attempt to program invalid half with 41h command\n");
> >  	else if (prog_status & 0x02)
> > -		printk(KERN_NOTICE"DSR.9,8: (10) Object Mode Program attempt "
> > -					"in region with Control Mode data\n");
> > +		pr_notice("DSR.9,8: (10) Object Mode Program attempt in region with Control Mode data\n");
> >  	else if (prog_status &  0x01)
> > -		printk(KERN_NOTICE"DSR.9,8: (01) Program attempt in region "
> > -						"with Object Mode data\n");
> > +		pr_notice("DSR.9,8: (01) Program attempt in region with Object Mode data\n");
> > +
> >  	if (!(dsr & DSR_READY_STATUS))
> > -		printk(KERN_NOTICE"DSR.7: (0) Device is Busy\n");
> > +		pr_notice("DSR.7: (0) Device is Busy\n");
> >  	if (dsr & DSR_ESS)
> > -		printk(KERN_NOTICE"DSR.6: (1) Erase Suspended\n");
> > +		pr_notice("DSR.6: (1) Erase Suspended\n");
> >  	if (dsr & DSR_ERASE_STATUS)
> > -		printk(KERN_NOTICE"DSR.5: (1) Erase/Blank check error\n");
> > +		pr_notice("DSR.5: (1) Erase/Blank check error\n");
> >  	if (dsr & DSR_PROGRAM_STATUS)
> > -		printk(KERN_NOTICE"DSR.4: (1) Program Error\n");
> > +		pr_notice("DSR.4: (1) Program Error\n");
> >  	if (dsr & DSR_VPPS)
> > -		printk(KERN_NOTICE"DSR.3: (1) Vpp low detect, operation "
> > -					"aborted\n");
> > +		pr_notice("DSR.3: (1) Vpp low detect, operation aborted\n");
> >  	if (dsr & DSR_PSS)
> > -		printk(KERN_NOTICE"DSR.2: (1) Program suspended\n");
> > +		pr_notice("DSR.2: (1) Program suspended\n");
> >  	if (dsr & DSR_DPS)
> > -		printk(KERN_NOTICE"DSR.1: (1) Aborted Erase/Program attempt "
> > -					"on locked block\n");
> > +		pr_notice("DSR.1: (1) Aborted Erase/Program attempt on locked block\n");
> >  }
> >  #endif /* __LINUX_MTD_PFOW_H */
> > 
> > 
> 
> Thanks,
> Miquèl