Re: [PATCH 0/4] spi: spi-mem/mtd: spinand: Prevent SPI NAND continuous reads on am65/am62

[Miquel Raynal <miquel.raynal@bootlin.com>]

Hello Mark,

On 28/04/2026 at 14:44:33 +02, Miquel Raynal <miquel.raynal@bootlin.com> wrote:

> On 26/03/2026 at 17:47:14 +01, Miquel Raynal <miquel.raynal@bootlin.com> wrote:
>
>> TI errata i2351 explains there is a problem with CS handling, SPI NOR
>> are immune to the problem, but the CS being deasserted spuriously when
>> there is DMA arbitration on long accesses (every 1023 bytes), SPI NAND
>> continuous reads cannot be leveraged.
>>
>> Link: https://www.ti.com/lit/er/sprz544c/sprz544c.pdf
>>
>> I created a 2-page read setup for testing all variants available on a
>> W35N chip wired to this controller. I reliably observed all variants to
>> always (in my tests) report correct data, except the 8D-8D-8D
>> variant *when setting an extended number of dummy cycles* (>= 12, so 24
>> dummy bytes). In this case, I got the first 6144 bytes correct (over
>> 8192), the rest being full of ones (0xFF), indicating the CS has likely
>> been deasserted there. This is not exactly 6 x 1023 bytes (?), but
>> close.
>>
>> This series shall be applied on top of the SPI NAND continuous read
>> series that I am also carrying, but ideally not too far in the future
>> because there are Winbond (continuous read capable) NAND chips mounted
>> on TI platforms AM62 based which could make use of that new feature and
>> expose the issue described above.
>
> Applied to nand/next (except the spi patch).

It seems like the spi bits have not been applied, can you check if you
can still apply them? Without these, people using this controller with
continuous read capable devices may observe spurious issues hard to
debug (due to the CS possibly not being kept asserted during long reads,
leading to the continuous read being cancelled by the SPI NAND).

Thanks,
Miquèl