Re: [PATCH v2 08/11] mtd: rawnand: jedec: Adapt the parameter page read to constraint controllers

[Miquel Raynal <miquel.raynal@xxxxxxxxxxx>]

Hi Boris,

Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx> wrote on Wed, 29 Apr
2020 18:04:05 +0200:

> On Wed, 29 Apr 2020 17:55:37 +0200
> Miquel Raynal <miquel.raynal@xxxxxxxxxxx> wrote:
> 
> > We already know that there are controllers not able to read the three
> > copies of the parameter page in one go. The workaround was to first
> > request the controller to assert command and address cycles on the
> > NAND bus to trigger a parameter page read, and then do a read
> > operation for each page.
> > 
> > But there are also controllers which are not able to split the
> > parameter page read between the command/address cycles and the actual
> > data operation.
> > 
> > All controllers are expected to be able to change the read column
> > though. So let's use a regular parameter page read operation for the
> > first iteration and use a change read column operation for the
> > following copies.
> > 
> > The extra command and address cycles sent over the NAND bus are
> > negligible compared to the amount of data that is being transferred
> > anyway.
> > 
> > Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
> > ---
> >  drivers/mtd/nand/raw/nand_jedec.c | 28 +++++++++++++++-------------
> >  1 file changed, 15 insertions(+), 13 deletions(-)
> > 
> > diff --git a/drivers/mtd/nand/raw/nand_jedec.c b/drivers/mtd/nand/raw/nand_jedec.c
> > index 15937e02c64f..b2be9056759a 100644
> > --- a/drivers/mtd/nand/raw/nand_jedec.c
> > +++ b/drivers/mtd/nand/raw/nand_jedec.c
> > @@ -25,7 +25,7 @@ int nand_jedec_detect(struct nand_chip *chip)
> >  {
> >  	struct mtd_info *mtd = nand_to_mtd(chip);
> >  	struct nand_memory_organization *memorg;
> > -	struct nand_jedec_params *p;
> > +	struct nand_jedec_params *p = NULL, *pbuf;  
> 
> Looks like you've merged 2 different commits here. I remember you had a
> separate commit adding pbuf to avoid an extra memcpy().
> 

Oops. Indeed I merged two commits by mistake, this is a leftover of the
operation, I'll fix it.

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