[PATCH 2/3] mtd: spi-nor: use rdid-dummy-ncycles DT property
Tudor Ambarus
tudor.ambarus at linaro.org
Thu Mar 20 00:44:50 PDT 2025
Hi, Rob,
On 3/19/25 11:30 PM, Rob Herring wrote:
> On Wed, Mar 19, 2025 at 06:47:44PM +0900, Takahiro Kuwano wrote:
>> There are infineon flashes [1] that require 8 dummy cycles for the
>> 1-1-1 Read ID command. Since the command is not covered by JESD216
>> or any other standard, get the number of dummy cycles from DT and use
>> them to correctly identify the flash.
>
> If Read ID fails, then couldn't you just retry with dummy cycles? Or
I think Read ID won't fail when the op requires 8 dummy cycles, it
probably just reads garbage on the first 8 cycles, so we risk to wrongly
match other flash IDs.
> would unconditionally adding dummy cycles adversely affect other chips?
Adding 8 dummy cycles to chips that don't need it, would mean ignoring
the first byte of the flash ID, thus we again risk to wrongly match
against other flash IDs.
>
> Otherwise, add a specific compatible to imply this requirement. Adding
> quirk properties doesn't scale.
Do you mean a flash name compatible, like "cyrs17b512,spi-nor"? The
problem that I see with that is that we no longer bind against the
generic jedec,spi-nor compatible, so people need to update their DT in
case they use/plug-in a different flash on their board.
Thanks,
ta
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