Re: [PATCH 7/8] mtd: spi-nor: factor out write_enable() for erase commands

[Huang Shijie <shijie.huang@intel.com>]

On Wed, Sep 10, 2014 at 12:05:37AM -0700, Brian Norris wrote:
> Hi Huang,
> 
> On Tue, Aug 12, 2014 at 08:59:12AM +0800, Huang Shijie wrote:
> > On Mon, Aug 11, 2014 at 11:48:18AM -0700, Brian Norris wrote:
> > > On Sat, Aug 09, 2014 at 06:52:34PM +0800, Huang Shijie wrote:
> > > > On Wed, Aug 06, 2014 at 06:17:01PM -0700, Brian Norris wrote:
> > > > > diff --git a/drivers/mtd/spi-nor/fsl-quadspi.c b/drivers/mtd/spi-nor/fsl-quadspi.c
> > > > > index 9c13622a0c7a..07fbfb0a7738 100644
> > > > > --- a/drivers/mtd/spi-nor/fsl-quadspi.c
> > > > > +++ b/drivers/mtd/spi-nor/fsl-quadspi.c
> > > > > @@ -738,11 +738,6 @@ static int fsl_qspi_erase(struct spi_nor *nor, loff_t offs)
> > > > >  	dev_dbg(nor->dev, "%dKiB at 0x%08x:0x%08x\n",
> > > > >  		nor->mtd->erasesize / 1024, q->chip_base_addr, (u32)offs);
> > > > >  
> > > > > -	/* Send write enable, then erase commands. */
> > > > > -	ret = nor->write_reg(nor, SPINOR_OP_WREN, NULL, 0, 0);
> > > > > -	if (ret)
> > > > > -		return ret;
> > > > > -
> > > > This write-enable is used for per-sector-erase, not for the whole chip
> > > > erase.
> > > > 
> > > > So if you really want to remove this code, you should add an extra write-enable
> > > > in the spi_nor_erase.
> > > 
> > > I don't understand your comment.
> > > 
> > > Before this patch, there is a write-enable command in:
> > >  * m25p80.c, per-sector erase
> > >  * fsl-quadspi, per-sector erase
> > >  * spi-nor.c, whole-chip erase
> > > 
> > > With this patch, I am factoring all of these out into spi_nor_erase().
> > > 
> > > What is the problem?
> > Hi Brian:
> >    For the spi_nor_erase(), the patch should like this:
> > 
> > diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
> > index c130bf7..26c48bc 100644
> > --- a/drivers/mtd/spi-nor/spi-nor.c
> > +++ b/drivers/mtd/spi-nor/spi-nor.c
> > @@ -324,6 +324,7 @@ static int spi_nor_erase(struct mtd_info *mtd, struct erase_info *instr)
> >  
> >  	/* whole-chip erase? */
> >  	if (len == mtd->size) {
> > +		write_enable(nor);
> >  		if (erase_chip(nor)) {
> >  			ret = -EIO;
> >  			goto erase_err;
> > @@ -337,6 +338,7 @@ static int spi_nor_erase(struct mtd_info *mtd, struct erase_info *instr)
> >  	/* "sector"-at-a-time erase */
> >  	} else {
> >  		while (len) {
> > +			write_enable(nor);
The difference is here.

you miss a write_enable for each sector's erase. 

thanks
Huang Shijie
> >  			if (nor->erase(nor, addr)) {
> >  				ret = -EIO;
> >  				goto erase_err;
> > 
> 
> How is your patch any different than mine? Mine has the exact same code,
> except it covers both paths by putting the write_enable() outside the
> conditional entirely.