Re: [PATCH] mtd: spinand: Handle the case where PROGRAM LOAD does not reset the cache

[Boris Brezillon <bbrezillon@xxxxxxxxxx>]

On Fri, 25 Jan 2019 12:09:10 +0100
Miquel Raynal <miquel.raynal@xxxxxxxxxxx> wrote:

> Hello,
> 
> Boris Brezillon <bbrezillon@xxxxxxxxxx> wrote on Thu, 24 Jan 2019
> 17:33:57 +0100:
> 
> > On Thu, 24 Jan 2019 17:16:37 +0100
> > Emil Lenngren <emil.lenngren@xxxxxxxxx> wrote:
> >   
> > > Hi,
> > > 
> > > Den tors 24 jan. 2019 kl 16:28 skrev Stefan Roese <sr@xxxxxxx>:    
> > > >
> > > > On 24.01.19 15:20, Boris Brezillon wrote:      
> > > > > Looks like PROGRAM LOAD (AKA write cache) does not necessarily reset
> > > > > the cache content to 0xFF (depends on vendor implementation), so we
> > > > > must fill the page cache entirely even if we only want to program the
> > > > > data portion of the page, otherwise we might corrupt the BBM or user
> > > > > data previously programmed in OOB area.
> > > > >
> > > > > Fixes: 7529df465248 ("mtd: nand: Add core infrastructure to support SPI NANDs")
> > > > > Reported-by: Stefan Roese <sr@xxxxxxx>
> > > > > Cc: <stable@xxxxxxxxxxxxxxx>
> > > > > Signed-off-by: Boris Brezillon <bbrezillon@xxxxxxxxxx>      
> > > >
> > > > Works fine (limited testing only yet), so:
> > > >
> > > > Tested-by: Stefan Roese <sr@xxxxxxx>
> > > > Reviewed-by: Stefan Roese <sr@xxxxxxx>
> > > >
> > > > Thanks,
> > > > Stefan
> > > >      
> > > 
> > > Can this quirk be made vendor specific?    
> > 
> > We can make it vendor specific, as long as it's an opt-in thing. This
> > way, the default behavior is the safest one, and only when we know a
> > chip does reset the cache content on a PROGRAM LOAD time can we add this
> > flag.  
> 
> I am fine with this approach.

Does that stand for a Reviewed-by/Acked-by? To make it clear, I was
saying that we should fix things first (with this fix) and only then
optimize things for chips that actually reset the cache when PROGRAM
LOAD is executed. I was not planning on sending a new version of this
patch, unless you see good reasons to do so.

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