[PATCH v5 07/12] mtd: nand: add Samsung K9GBG08U0A-M to nand_ids table

[Ezequiel Garcia]

On 20 July 2015 at 15:08, Brian Norris <computersforpeace at gmail.com> wrote:
> Hi Ezequiel,
>
> On Sun, May 24, 2015 at 03:42:11PM -0300, Ezequiel Garcia wrote:
>> On 05/20/2015 11:43 AM, Antoine Tenart wrote:
>> [..]
>> >>
>> >> I just had a look on the datasheet, and I you're right, the nand should
>> >> support JDEC. However I get a "No NAND device found" error when
>> >> reverting this patch.
>> >>
>> >> It seems nand_flash_detect_jedec() is not reading "JDEC" and is returning
>> >> directly. I'm having a look at this.
>> >
>> > So, I can read 'J', 'E', 'D' and 'E' but then I got 0xff's. So I tried
>> > to only check of JEDE in nand_flash_detect_jedec() but the JEDEC
>> > parameter page was then not valid.
>> >
>>
>> This uncovers two different bugs in the driver.
>>
>> 1. read_id_bytes is either '2' or '4', but JEDEC detections needs at
>> least 5 bytes.
>>
>> 2. The initial buffer (to read the ID and the parameter page) has
>> 256 bytes, but the JEDEC parameter page is 512-bytes.
>>
>> And while at it, the driver doesn't seem to support reading the
>> redundant parameter pages (recently reported on barebox ML [1]). So this
>> is a third bug.
>>
>> Would you try setting read_id_bytes to '5' and also increasing the READ_PARAM
>> transfer length? Something like this:
>
> I'm trying to parse through the latest pxa3xx_nand patches, and I'm a
> bit lost. Did this piece get dropped on the floor?
>

As far as I can see, yes. Regarding this particular patch, the flash device
supports JEDEC detection but the driver needs a fix.

Hopefully, Antoine will submit a fix in the future.

> At any rate, it looks like there are a few more things to fix in
> Antoine's latest work, so I can't quite take them. Correct me if I'm
> misunderstanding.
>

The current patchset under discussion is "v2 mtd: pxa3xx_nand: rework
the timing setup":

http://lists.infradead.org/pipermail/linux-mtd/2015-July/060033.html

We are trying to get that sorted out, so we can move to the Berlin SoC support.

Cheers,
-- 
Ezequiel García, VanguardiaSur
www.vanguardiasur.com.ar