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

[Simon Goldschmidt]

+ Marek for the socfpga platform, see below

On 07.12.2017 06:49, Jagan Teki wrote:
> 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.

Any update here? The last input on this is about five months old! This 
is the last patch I need to run my socfpga board from qspi.

I added Marek to the discussion as at least the SoCrates board does not 
have a reset connected to the qspi chip and needs this as well. Note 
that the system boot rom does not have a problem with the chip being in 
4-byte mode but SPL fails to load U-Boot from qspi.

I'm open to other solutions for this problem (like using 4-byte 
opcodes), but since they did not emerge, yet, can we please push this 
fix to get it working? Also, I don't want to wait for the long pending 
Linux backport of spi flash support: this is a bug right now, let's fix 
it independently of new features!

Thanks,
Simon