Re: [PATCH v3 15/22] mtd: rawnand: fsmc: Stop implementing ->select_chip()

[Linus Walleij <linus.walleij@xxxxxxxxxx>]

On Wed, Jan 9, 2019 at 8:45 PM Boris Brezillon <bbrezillon@xxxxxxxxxx> wrote:
> [Me]
> > I will experiment with some delay valued and try to read some data
> > sheets but if you already have hints on how to deal with this I'd
> > like to hear!
>
> Might be caused by a missing barrier: when de-asserting the CE line, we
> must make sure all accesses to the ->data_va range have been done.
> Can you try with the following diff applied?

Tried it, but it sadly does not help :/

The machine crashes at the same place when doing ther first
64 bytes read.

I suppose the old code would hold CE enabled across all the
commands?

Since the old code contained this:

       /* Support only one CS */
       if (chipnr > 0)
               return;

I guess that is normal for FSMC: only one CS. It seems a bit
aggressive to toggle CS on/off between every command like this,
I suspect the FSMC isn't really built for that but shakes apart
or something.

I will send a version of your patch that keeps CS enabled
for your consideration. (worksforme).

Yours,
Linus Walleij

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