Re: [PATCH 2/3] mtd: rawnand: arasan: Ensure program page operations are successful

Miquel Raynal
2023-09-12T14:17:58Z

Hi Michal,

michal.simek@amd.com wrote on Tue, 12 Sep 2023 15:55:23 +0200:

> Hi Miquel,
>
> On 9/11/23 17:52, Miquel Raynal wrote:
> > Hi Michal,
> >
> > miquel.raynal@bootlin.com wrote on Mon, 17 Jul 2023 21:42:20 +0200:
> >
> >> The NAND core complies with the ONFI specification, which itself
> >> mentions that after any program or erase operation, a status check
> >> should be performed to see whether the operation was finished *and*
> >> successful.
> >>
> >> The NAND core offers helpers to finish a page write (sending the
> >> "PAGE PROG" command, waiting for the NAND chip to be ready again, and
> >> checking the operation status). But in some cases, advanced controller
> >> drivers might want to optimize this and craft their own page write
> >> helper to leverage additional hardware capabilities, thus not always
> >> using the core facilities.
> >>
> >> Some drivers, like this one, do not use the core helper to finish a page
> >> write because the final cycles are automatically managed by the
> >> hardware. In this case, the additional care must be taken to manually
> >> perform the final status check.
> >>
> >> Let's read the NAND chip status at the end of the page write helper and
> >> return -EIO upon error.
> >>
> >> Cc: Michal Simek <michal.simek@amd.com>
> >> Cc: stable@vger.kernel.org
> >> Fixes: 88ffef1b65cf ("mtd: rawnand: arasan: Support the hardware BCH ECC engine")
> >> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> >>
> >> ---
> >>
> >> Hello Michal,
> >>
> >> I have not tested this, but based on a report on another driver, I
> >> believe the status check is also missing here and could sometimes
> >> lead to unnoticed partial writes.
> >>
> >> Please test on your side that everything still works and let me
> >> know how it goes.
> >
> > Any news from the testing team about patches 2/3 and 3/3?
>
> I asked Amit to test and he didn't get back to me even I asked for it couple of times.

Ok.

> Can you please tell me how to test it? I will setup HW myself and test it and get back to you.

I believe setting up the board to use the hardware BCH engine and
performing basic erase/write/read testing with a known file and check
it still behaves correctly would work. You can also run

nandbiterrs -i /dev/mtdx

as a second step and verify there is no difference with and without the
patch and finally check the impact:

flash_speed -d -c 10 /dev/mtdx
(be careful: this is a destructive operation)

Thanks,
Miquèl