[U-Boot] [PATCH] sf: ensure flash device is in 3-byte address mode

[Goldschmidt Simon]

+ Lukasz (as a reviewer of my patch[1])

On Mon, Dec 4, 2017 at 8:20, Jagan Teki wrote:
> This is the patch[1] for 4-byte addressing, but I would wonder how can proceed
> operations with 4-byte if we disable during probe.
> 
> [1] http://git.denx.de/?p=u-boot-
> spi.git;a=commitdiff;h=fd0c22a90772379c4c11ba09347d36cc8ee17dca

OK, so your patch does something different than what I did.

I was trying to keep the change to U-Boot as small as possible, only
fixing this issue I was seeing:

After a soft-reboot where the SPI chip was not reset, it is left in
4-byte addressing mode (linux uses this mode, obviously). Remember
that 4-byte mode is not a permanent setting, so we can enter and
leave it any time we like by issuing a command.

U-Boot uses the Bank Address Register (BAR) for spi flash chips with
more than 16 MByte, so it impclitly assumes that the chip is in
3-byte address mode. As I see it, your patch is worth a discussion
named "should we use 4-byte addressing mode on spi flash chips?".
I do think this is a better alternative than writing BAR! But this
change probably needs discussion and testing.

Until we discussed and tested that, could we push my patch[1] into
v2018.01? This is really a rather tiny bugfix I need for soft reboot,
compared to using 4-byte address mode.

[1] https://patchwork.ozlabs.org/patch/826919/

Thanks,
Simon