[U-Boot] [PATCHv3] mtd: sf: Add CONFIG_SPI_N25Q256A_RESET for software-reset

[Marek Vasut]

On Sunday, May 10, 2015 at 07:43:52 PM, Pavel Machek wrote:
> On Sun 2015-05-10 18:25:59, Marek Vasut wrote:
> > On Sunday, May 10, 2015 at 02:24:01 PM, Jagan Teki wrote:
> > > On 10 May 2015 at 16:19, Pavel Machek <pavel at denx.de> wrote:
> > > > On Sun 2015-05-10 11:15:41, Pavel Machek wrote:
> > > > Add reset for N25Q256A SPI NOR, as U-Boot SPL 2013-socfpga (only
> > > > version working on that board) sets 4-byte addressing mode.
> > > > 
> > > > Signed-off-by: Pavel Machek <pavel at denx.de>
> > 
> > So, I took one more look into the datasheet [1]. With this chip, which
> > is 128Mbit (16MByte), you don't even use 4-byte addressing so you don't
> > care about it at all.
> > 
> > But you actually do care about it if your hardware is broken and you use
> > the N25Q256A [2] part. If the problem really is just between the
> > U-Boot
> 
> No, I actually care whenever I use the U-boot SPL 2013, which is the
> only option today. And I explained it to you already. (Additionally,
> hardware might be broken. That has nothing to do with _this_ problem).

OK

> > SPL and U-Boot (which I doubt btw), you can probably augment U-Boot such
> > that it reads FSR (Flag Status Register, see page 27, table 17, bit 0).
> > This bit tells you whether the part is in 3-byte or 4-byte mode and you
> > can read this register in either mode.
> 
> How does reading Micron-specific register help with code being too
> Micron-specific is unclear to me.

Just add a micron-specific hook and check the register on Micron parts
only. This would eliminate the need for new CONFIG_foo_bar option, which
is always a plus.

Best regards,
Marek Vasut