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

[Jagan Teki]

On Tue, Dec 5, 2017 at 11:50 AM, Goldschmidt Simon
<sgoldschmidt at de.pepperl-fuchs.com> wrote:
> + 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.

OK, will review your patch.

thanks!
-- 
Jagan Teki
Free Software Engineer | www.openedev.com
U-Boot, Linux | Upstream Maintainer
Hyderabad, India.