Re: [PATCH] mtd: spi-nor: Only set Micron quad-read mode when controller in 4-lane TX mode

[Mike Looijmans]

ïOn 30-06-15 17:42, Graham Moore wrote:
> On 06/30/2015 06:17 AM, Mike Looijmans wrote:
> > Micron QUAD mode expects command, address and data on 4 lanes instead of just
> > one for command (extended SPI mode). This requires the controller to be in a
> > special mode, so check first if the controller could be in that mode. If a
> > controller does not have the SPI_TX_QUAD mode set, this setting has no chance
> > of being valid at all, so don't try to enable it then, and just keep using
> > the extended SPI mode.
> >
> > Tested on a Zynq 7000 with a n25q256a flash chip, this failed to function
> > because of the introduction of:
> > "driver:mtd:spi-nor: Add quad I/O support for Micron spi nor"
> > This commit sets QUAD mode for most Micron chips without asking the controller
> > whether it's possible to do so, and without telling the controller that a
> > different mode is required, so it couldn't work.
> >
> > Signed-off-by: Mike Looijmans <mike.looijmans@xxxxxxxx>
> > ---
> >   drivers/mtd/spi-nor/spi-nor.c | 2 ++
> >   1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
> > index e8f6131..10ba94f 100644
> > --- a/drivers/mtd/spi-nor/spi-nor.c
> > +++ b/drivers/mtd/spi-nor/spi-nor.c
> > @@ -1398,6 +1398,8 @@ static int set_quad_mode(struct spi_nor *nor, struct
> > flash_info *info)
> >           }
> >           return status;
> >       case CFI_MFR_ST:
> > +        if (!(nor->spi->mode & SPI_TX_QUAD))
> > +            return 0;
>
> This is a great idea, but what codebase are you working from?  My l2-mtd tree
> doesn't have a 'spi' member of spi_nor, and this case statement is around line
> 977, not 1398.

I was working from the Xilinx kernel tree, and there's a lot of changes there. 
The one that added the "struct spi_device* spi" to the nor struct is:
63697f5cf9a6201556947ef0ea29442843e5ba61 mtd: spi-nor: Changes for stacked and 
parallel

> >           status = micron_quad_enable(nor);
> >           if (status) {
> >               dev_err(nor->dev, "Micron quad-read not enabled\n");




Kind regards,

Mike Looijmans
System Expert

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