Re: [PATCH v1 5/7] mtd: fsl-quadspi: get the dummy cycles for DDR Quad read from the DT property

[Huang Shijie <shijie8@gmail.com>]

On Thu, Apr 24, 2014 at 03:41:54PM +0200, Marek Vasut wrote:
> On Thursday, April 24, 2014 at 06:58:40 AM, Huang Shijie wrote:
> > On Wed, Apr 23, 2014 at 09:48:50PM +0200, Marek Vasut wrote:
> > > On Wednesday, April 23, 2014 at 12:16:53 PM, Huang Shijie wrote:
> > > > Check the "spi-nor,ddr-quad-read-dummy" DT property to get the
> > > > dummy cycles for DDR quad read.
> > > > 
> > > > Signed-off-by: Huang Shijie <b32955@freescale.com>
> > > > ---
> > > > 
> > > >  drivers/mtd/spi-nor/fsl-quadspi.c |    7 +++++++
> > > >  1 files changed, 7 insertions(+), 0 deletions(-)
> > > > 
> > > > diff --git a/drivers/mtd/spi-nor/fsl-quadspi.c
> > > > b/drivers/mtd/spi-nor/fsl-quadspi.c index 8d659a2..15bdeb9 100644
> > > > --- a/drivers/mtd/spi-nor/fsl-quadspi.c
> > > > +++ b/drivers/mtd/spi-nor/fsl-quadspi.c
> > > > @@ -883,6 +883,7 @@ static int fsl_qspi_probe(struct platform_device
> > > > *pdev)
> > > > 
> > > >  	for_each_available_child_of_node(dev->of_node, np) {
> > > >  	
> > > >  		const struct spi_device_id *id;
> > > >  		char modalias[40];
> > > > 
> > > > +		u32 dummy = 0;
> > > > 
> > > >  		/* skip the holes */
> > > >  		if (!has_second_chip)
> > > > 
> > > > @@ -918,6 +919,12 @@ static int fsl_qspi_probe(struct platform_device
> > > > *pdev) if (ret < 0)
> > > > 
> > > >  			goto map_failed;
> > > > 
> > > > +		/* Set the dummy cycles for the DDR Quad Read */
> > > > +		ret = of_property_read_u32(np, "spi-nor,ddr-quad-read-dummy",
> > > > +				&dummy);
> > > > +		if (!ret && dummy > 0 && dummy < 8)
> > > > +			nor->read_dummy = dummy;
> > > 
> > > Is there any reason for the upper limit on number of dummy cycles ?
> > 
> > I actually tested two kinds of NOR flash, the Spansion s25fl128s and Micron
> > N25q256a. The dummy cycles are all less then 8.
> 
> I'm all for having a limit if you can justify why number 8 is the upper limit. 
> If there's no justification for it, let's remove it.
ok.

thanks
Huang Shijie