Re: mtd raw nand denali.c broken for Intel/Altera Cyclone V

From: Masahiro Yamada <yamada.masahiro@socionext.com>
To: Tim Sander <tim@krieglstein.org>
Cc: Vignesh Raghavendra <vigneshr@ti.com>,
	Marek Vasut <marek.vasut@gmail.com>,
	Richard Weinberger <richard@nod.at>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Dinh Nguyen <dinguyen@kernel.org>,
	linux-mtd <linux-mtd@lists.infradead.org>,
	Miquel Raynal <miquel.raynal@bootlin.com>,
	Brian Norris <computersforpeace@gmail.com>,
	David Woodhouse <dwmw2@infradead.org>
Subject: Re: mtd raw nand denali.c broken for Intel/Altera Cyclone V
Date: Fri, 27 Sep 2019 02:47:33 +0900	[thread overview]
Message-ID: <CAK7LNASG+b03NDhrenB9yfvgYDVpYSnb2vSCu_-DB8dh70boMg@mail.gmail.com> (raw)
In-Reply-To: <23083624.r2bJSIadJk@dabox>

Hi Tim,

On Thu, Sep 26, 2019 at 6:10 PM Tim Sander <tim@krieglstein.org> wrote:
>
> Hi
>
> Am Mittwoch, 11. September 2019, 04:37:46 CEST schrieb Masahiro Yamada:
> > Hi Dinh,
> >
> > On Wed, Sep 11, 2019 at 12:22 AM Dinh Nguyen <dinguyen@kernel.org> wrote:
> > > On 9/10/19 8:48 AM, Tim Sander wrote:
> > > > Hi
> > > >
> > > > I have noticed that my SPF records where not in place after moving the
> > > > server, so it seems the mail didn't go to the mailing list. Hopefully
> > > > that's fixed now.> >
> > > > Am Dienstag, 10. September 2019, 09:16:37 CEST schrieb Masahiro Yamada:
> > > >> On Fri, Sep 6, 2019 at 9:39 PM Tim Sander <tim@krieglstein.org> wrote:
> > > >>> Hi
> > > >>>
> > > >>> I have noticed that there multiple breakages piling up for the denali
> > > >>> nand
> > > >>> driver on the Intel/Altera Cyclone V. Unfortunately i had no time to
> > > >>> track
> > > >>> the mainline kernel closely. So the breakage seems to pile up. I am a
> > > >>> little disapointed that Intel is not on the lookout that the kernel
> > > >>> works
> > > >>> on the chips they are selling. I was really happy about the state of
> > > >>> the
> > > >>> platform before concerning mainline support.
> > > >>>
> > > >>> The failure starts with kernel 4.19 or stable kernel release 4.18.19.
> > > >>> The
> > > >>> commit is ba4a1b62a2d742df9e9c607ac53b3bf33496508f.
> > > >>
> > > >> Just for clarification, this corresponds to
> > > >> 0d55c668b218a1db68b5044bce4de74e1bd0f0c8 upstream.
> > > >>
> > > >>> The problem here is that
> > > >>> our platform works with a zero in the SPARE_AREA_SKIP_BYTES register.
> > > >>
> > > >> Please clarify the scope of "our platform".
> > > >> (Only you, or your company, or every individual using this chip?)
> > > >
> > > > The company i work for uses this chip as a base for multiple products.
> > > >
> > > >> First, SPARE_AREA_SKIP_BYTES is not the property of the hardware.
> > > >> Rather, it is about the OOB layout, in other words, this parameter
> > > >> is defined by software.
> > > >>
> > > >> For example, U-Boot supports the Denali NAND driver.
> > > >> The SPARE_AREA_SKIP_BYTES is a user-configurable parameter:
> > > >> https://github.com/u-boot/u-boot/blob/v2019.10-rc3/drivers/mtd/nand/raw
> > > >> /Kcon fig#L112
> I am using barebox for booting. I looked at the code and found a comment in
> denali_hw_init:
>          * tell driver how many bit controller will skip before
>          * writing ECC code in OOB, this register may be already
>          * set by firmware. So we read this value out.
>          * if this value is 0, just let it be.
>
> I have checked the barebox code and the denali register SPARE_AREA_SKIP_BYTES
> (offset 0x230) is read only once on booting. I have not found any occurrence of
> the register being set by barebox. So i would concur as the value is zero in
> my case that the boot ROM seems not to set the value. The code in barebox is
> mostly imported from linux in 2015 which is before the reorganization which
> happened on the linux side later on.
>
> > > >>
> > > >>
> > > >> Your platform works with a zero in the SPARE_AREA_SKIP_BYTES register
> > > >> because the NAND chip on the board was initialized with a zero
> > > >> set to the SPARE_AREA_SKIP_BYTES register.
> > > >>
> > > >> If the NAND chip had been initialized with 8
> > > >> set to the SPARE_AREA_SKIP_BYTES register, it would have
> > > >> been working with 8 to the SPARE_AREA_SKIP_BYTES.
> > > >>
> > > >> The Boot ROM is the only (semi-)software that is unconfigurable by
> > > >> users,
> > > >> so the value of SPARE_AREA_SKIP_BYTES should be aligned with
> > > >> the boot ROM.
> > > >> I recommend you to check the spec of the boot ROM.
> > > >
> > > > We boot from NOR flash. That's why i didn't see a problem booting
> > > > probably.
> > > >
> > > >> (The maintainer of the platform, Dihn is CC'ed,
> > > >> so I hope he will jump in)
> > > >
> > > > Yes i hope so too.
> > >
> > > I don't have access to a NAND device at the moment. I'll try to find one
> > > and debug.
> I have hardware available to me, so i would be happy to test any ideas/
> guesses.

You previously mentioned,
"We boot from NOR flash. That's why i didn't see a problem booting probably."

Could you try the NAND device as the boot source?

- Flash the boot image into the NAND device,
  changing the value for SPARE_AREA_SKIP_BYTES.
 -  Please find out the appropriate value for SPARE_AREA_SKIP_BYTES
    for booting successfully.

-- 
Best Regards
Masahiro Yamada

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