[U-Boot] [PATCH v2 08/16] tegra: nand: fix read_byte required for proper onfi detection

[Marcel Ziswiler]

On 27 July 2015 22:00:15 CEST, Scott Wood <scottwood at freescale.com> wrote:
>On Tue, 2015-07-21 at 00:35 +0200, Marcel Ziswiler wrote:
>> From: Marcel Ziswiler <marcel.ziswiler at toradex.com>
>> 
>> Fix PIO read_byte() implementation not only used for the legacy READ
>ID
>> but also the PARAM command now required for proper ONFI detection.
>> 
>> This fix is inspired by Lucas Stach's Linux Tegra NAND driver of
>late.
>
>Could you explain a bit more how this fixes issues with READ PARAM?

I vaguely remember that those commands are special on 16-bit bus NAND (e.g. always return 8-bit data regardless) and later Linux MTD fixed/changed the way this is handled which in turn broke once U-Boot pulled that in. Which as explained in my commit message this fixes by doing what Lucas does in Linux (not mainline yet but getting there soon I hope).

>> While at it also disable subpage writes.
>
>Why are these two changes combined?

Well just because it's a one line fix but if required I can split that in a separate patch as well.