Re: Questions about the Freescale/NXP QuadSPI controller

[Huang Shijie <sjhuang@xxxxxxxxxxx>]

On Wed, Sep 19, 2018 at 01:02:11PM +0200, Lukasz Majewski wrote:
> Hi Frieder,
> 
> > Hi Lukasz,
> > 
> > On 19.09.2018 00:42, Lukasz Majewski wrote:
> > > Dear All,
> > > 
> > > Maybe I do jump a bit off topic here, but...
> > > 
> > > I've read through the following thread:
> > > https://patchwork.ozlabs.org/patch/939885/
> > > 
> > > And it mentions some issues with reading AHB content (buffers) in
> > > fsl-quadspi.c driver discovered when new QuadSPI driver was
> > > developed.  
> > 
> > The only setup with two chips that is known to be problematic with
> > the new driver, is when both chips are connected to the same bus
> > (e.g. QSPIA) using separate chip selects.
> 
> I'm using QSPI0 controller, with two memories connected to QSPI0_A and
> QSPI0_B lines.
> 
> > 
> > Does your board use this kind of setup, or are the two chips
> > connected two different buses (QSPIA and QSPIB)?
> > 
> > Have you tested the new driver? It would be great to receive some
> > more feedback.
> 
> I will check (test) this new driver. No problem.
> 
> > 
> > > I do have a setup with qspi0 having two SPI memories connected (2x16
> > > MiB), and I'm wondering if anybody has some more info regarding:
> > > 
> > > (What's more is that there is a bug in
> > >   * the "IP Command Read" in the Vybrid.) found here:
> > > https://elixir.bootlin.com/linux/v4.19-rc4/source/drivers/mtd/spi-nor/fsl-quadspi.c#L671
> > > 
> > > I've googled for some errata or known issues for vybryd's QSPI IP
> > > block (vf610) but without luck so far ...  
> > 
> > Unfortunately I don't know the background for this comment.
> 
> The comment was added by some Freescale employee when the driver was
> added to Linux (by Huang - CC'ed).

I was told that there was a hardware bug in the vybryd when we use the "IP Command Read":
    If you use the "IP Command Read", you will not get the correct data.

So I added that comment.

I suggest that do not use the "IP Command Read" for vybryd.

Thanks
Huang Shijie

> 
> > Is your 
> > board using VF610?
> 
> Yes, it uses vf610 (A5 + M4 cores).
>