Re: [PATCH v2 4/8] mtd: spi-nor: core: Introduce method for RDID op

[Michael Walle]

Am 2022-03-22 08:32, schrieb Pratyush Yadav:
> On 21/03/22 11:56PM, Michael Walle wrote:
> > Am 2022-02-28 12:17, schrieb Tudor Ambarus:
> > > RDID is used in the core to auto detect the flash, but also by some
> > > manufacturer drivers that contain flashes that support Octal DTR mode,
> > > so that they can read the flash ID after the switch to Octal DTR was
> > > made
> > > to test if the switch was successful. Introduce a core method for RDID
> > > op
> > > to avoid code duplication.
> >
> > Some or all? Is that specific to the flash or can we just check that
> > readid works in spi_nor_octal_dtr_enable()? That way we could also
> > just get rid of the proto parameter for the read_id because it can
> > be called after we set the reg_proto.
>
> It is specific to the flash. Not all flashes support RDID in 8D mode.
> And the RDID command is also different in 8D mode for various flashes.
> For example, Micron MT35XU512ABA flash expects 8 dummy cycles and 0
> address cycles. Cypress S28HS512T expects 4 address cycles and 3 dummy
> cycles.
>
> The octal_dtr_enable hook would know what parameters to use but it is
> harder for the core to know since this information is not discoverable
> via SFDP.

Ah, I see, thanks for clarification.

-michael