Re: [PATCH v3 09/13] mtd: rawnand: onfi: Adapt the parameter page read to constraint controllers

[Miquel Raynal <miquel.raynal@bootlin.com>]

Boris Brezillon <boris.brezillon@collabora.com> wrote on Mon, 4 May
2020 10:47:22 +0200:

> On Mon,  4 May 2020 10:24:10 +0200
> Miquel Raynal <miquel.raynal@bootlin.com> 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 simple 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.
> > 
> > Let's use a regular PARAMETER PAGE READ operation for the first
> > iteration and use either a CHANGE READ COLUMN or a simple DATA READ
> > operation for the following copies, depending on what the controller
> > supports. The default behavior for non-exec-op compliant drivers
> > remains the same: DATA READ.
> > 
> > Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> > ---
> >  drivers/mtd/nand/raw/nand_onfi.c | 21 ++++++++++++++-------
> >  1 file changed, 14 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/mtd/nand/raw/nand_onfi.c b/drivers/mtd/nand/raw/nand_onfi.c
> > index e6ffbe8c9a0c..49cb04c02e9f 100644
> > --- a/drivers/mtd/nand/raw/nand_onfi.c
> > +++ b/drivers/mtd/nand/raw/nand_onfi.c
> > @@ -143,6 +143,7 @@ int nand_onfi_detect(struct nand_chip *chip)
> >  	struct nand_memory_organization *memorg;
> >  	struct nand_onfi_params *p = NULL, *pbuf;
> >  	struct onfi_params *onfi;
> > +	bool use_datain = false;
> >  	int onfi_version = 0;
> >  	char id[4];
> >  	int i, ret, val;
> > @@ -160,15 +161,21 @@ int nand_onfi_detect(struct nand_chip *chip)
> >  	if (!pbuf)
> >  		return -ENOMEM;
> >  
> > -	ret = nand_read_param_page_op(chip, 0, NULL, 0);
> > -	if (ret) {
> > -		ret = 0;
> > -		goto free_onfi_param_page;
> > -	}
> > +	if (!nand_has_exec_op(chip) ||
> > +	    (nand_read_data_op(chip, &pbuf[0], sizeof(*pbuf), true, true) == 0))  
> 
> Just nitpicking, but isn't checkpatch complaining about unneeded parens?

Mmmh no, where? I think there is no need for (!nand_has_exec_op(chip))
if this is what you mean? Checkpatch --strict does not produce a
warning here.

> Any reason you didn't use
> 
> 	    !nand_read_data_op(chip, &pbuf[0], sizeof(*pbuf), true, true)

I usually write conditions this way, but here I read it like "if not
nand_read_data_op is supported" which means the opposite of what it is
doing. Instead, I read the "== 0" as "I expect it to return 0 and
it means it is okay". Maybe its purely personal :)

> 
> here?
> 
> The rest looks good,
> 
> Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
> 

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