Re: [PATCH v3 5/5] mtd: rawnand: brcmnand: Fix mtd oobsize

[William Zhang]

Hi Miquel,

On 07/04/2023 08:30 AM, Miquel Raynal wrote:
> Hi William,
>
> william.zhang@xxxxxxxxxxxx wrote on Tue, 27 Jun 2023 12:37:38 -0700:
>
> > brcmnand controller can only access the flash spare area up to certain
> > bytes based on the ECC level. It can be less than the actual flash spare
> > area size. For example, for many NAND chip supporting ECC BCH-8, it has
> > 226 bytes spare area. But controller can only uses 218 bytes. So brcmand
> > driver overrides the mtd oobsize with the controller's accessible spare
> > area size. When the nand base driver utilizes the nand_device object, it
> > resets the oobsize back to the actual flash spare aprea size from
> > nand_memory_organization structure and controller may not able to access
> > all the oob area as mtd advises.
> >
> > This change fixes the issue by overriding the oobsize in the
> > nand_memory_organization structure to the controller's accessible spare
> > area size.
>
> I am clearly not a big fan of this solution. memorg should be and
> remain a read only object. Can you please find another solution?
I was debating on this too but I don't see option because there is no 
other hooks after nanddev_init to set the mtd->oobsize as far as I can 
see and I see there were similar fixes for other controller drivers 
after the nand device object init was committed, for example:
Fixes: 629a442cad5f ("mtd: rawnand: Fill memorg during detection")

I will think through this again but I am open to any suggestion.

> > Fixes: a7ab085d7c16 ("mtd: rawnand: Initialize the nand_device object")
> > Signed-off-by: William Zhang <william.zhang@xxxxxxxxxxxx>
> >
> > ---
> >
> > Changes in v3: None
> > Changes in v2: None
> >
> >   drivers/mtd/nand/raw/brcmnand/brcmnand.c | 7 +++++--
> >   1 file changed, 5 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/mtd/nand/raw/brcmnand/brcmnand.c b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
> > index 407bf79cbaf4..39c7f547db1f 100644
> > --- a/drivers/mtd/nand/raw/brcmnand/brcmnand.c
> > +++ b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
> > @@ -2647,6 +2647,8 @@ static int brcmnand_setup_dev(struct brcmnand_host *host)
> >   	struct nand_chip *chip = &host->chip;
> >   	const struct nand_ecc_props *requirements =
> >   		nanddev_get_ecc_requirements(&chip->base);
> > +	struct nand_memory_organization *memorg =
> > +		nanddev_get_memorg(&chip->base);
> >   	struct brcmnand_controller *ctrl = host->ctrl;
> >   	struct brcmnand_cfg *cfg = &host->hwcfg;
> >   	char msg[128];
> > @@ -2668,10 +2670,11 @@ static int brcmnand_setup_dev(struct brcmnand_host *host)
> >   	if (cfg->spare_area_size > ctrl->max_oob)
> >   		cfg->spare_area_size = ctrl->max_oob;
> >   	/*
> > -	 * Set oobsize to be consistent with controller's spare_area_size, as
> > -	 * the rest is inaccessible.
> > +	 * Set mtd and memorg oobsize to be consistent with controller's
> > +	 * spare_area_size, as the rest is inaccessible.
> >   	 */
> >   	mtd->oobsize = cfg->spare_area_size * (mtd->writesize >> FC_SHIFT);
> > +	memorg->oobsize = mtd->oobsize;
> >   
> >   	cfg->device_size = mtd->size;
> >   	cfg->block_size = mtd->erasesize;
>
>
> Thanks,
> Miquèl

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