linux-kernel - Re: [PATCH v9 13/19] mtd: spi-nor: sfdp: do not make invalid quad enable fatal

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Date:   Mon, 1 Jun 2020 14:28:52 +0530
From:   Pratyush Yadav <p.yadav@...com>
To:     <Tudor.Ambarus@...rochip.com>
CC:     <miquel.raynal@...tlin.com>, <richard@....at>, <vigneshr@...com>,
        <broonie@...nel.org>, <Nicolas.Ferre@...rochip.com>,
        <alexandre.belloni@...tlin.com>, <Ludovic.Desroches@...rochip.com>,
        <matthias.bgg@...il.com>, <michal.simek@...inx.com>,
        <linux-mtd@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
        <linux-spi@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>, <nsekhar@...com>,
        <boris.brezillon@...labora.com>, <masonccyang@...c.com.tw>
Subject: Re: [PATCH v9 13/19] mtd: spi-nor: sfdp: do not make invalid quad
 enable fatal

Hi Tudor,

On 30/05/20 06:42PM, Tudor.Ambarus@...rochip.com wrote:
> On Monday, May 25, 2020 12:15:38 PM EEST Pratyush Yadav wrote:
> > EXTERNAL EMAIL: Do not click links or open attachments unless you know the
> > content is safe
> > 
> > The Micron MT35XU512ABA flash does not support the quad enable bit. But
> > instead of programming the Quad Enable Require field to 000b ("Device
> > does not have a QE bit"), it is programmed to 111b ("Reserved").
> > 
> > While this is technically incorrect, it is not reason enough to abort
> > BFPT parsing. Instead, continue BFPT parsing assuming there is no quad
> > enable bit present.
> > 
> > Signed-off-by: Pratyush Yadav <p.yadav@...com>
> > ---
> >  drivers/mtd/spi-nor/sfdp.c | 8 +++-----
> >  1 file changed, 3 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/mtd/spi-nor/sfdp.c b/drivers/mtd/spi-nor/sfdp.c
> > index 052cabb52df9..9fd3d8d9a127 100644
> > --- a/drivers/mtd/spi-nor/sfdp.c
> > +++ b/drivers/mtd/spi-nor/sfdp.c
> > @@ -576,10 +576,6 @@ static int spi_nor_parse_bfpt(struct spi_nor *nor,
> > 
> >         /* Quad Enable Requirements. */
> >         switch (bfpt.dwords[BFPT_DWORD(15)] & BFPT_DWORD15_QER_MASK) {
> > -       case BFPT_DWORD15_QER_NONE:
> > -               params->quad_enable = NULL;
> > -               break;
> > -
> >         case BFPT_DWORD15_QER_SR2_BIT1_BUGGY:
> >                 /*
> >                  * Writing only one byte to the Status Register has the
> > @@ -616,8 +612,10 @@ static int spi_nor_parse_bfpt(struct spi_nor *nor,
> >                 params->quad_enable = spi_nor_sr2_bit1_quad_enable;
> >                 break;
> > 
> > +       case BFPT_DWORD15_QER_NONE:
> >         default:
> > -               return -EINVAL;
> > +               params->quad_enable = NULL;
> > +               break;
> 
> I would just add a dev_dbg message and break the switch.
> 	dev_dbg(nor->dev, "BFPT QER reserved value used.\n");
> 	break;
> 
> You will then have to set params->quad_enable = NULL; in a post_bfpt hook.

Ok. Will re-roll.

BTW, are you planning to pick up the xSPI/8D support for 5.8? It has 
been outstanding for quite some time now and it would be great if it can 
make it through this merge window.

-- 
Regards,
Pratyush Yadav
Texas Instruments India