Re: [PATCH v4 10/27] mtd: spi-nor: swp: Create a helper that writes SR, CR and checks

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

On 06/05/2026 at 11:06:22 +02, "Michael Walle" <mwalle@kernel.org> wrote:

> On Tue May 5, 2026 at 6:05 PM CEST, Pratyush Yadav wrote:
>> On Fri, Apr 03 2026, Miquel Raynal wrote:
>>
>>> There are many helpers already to either read and/or write SR and/or CR,
>>> as well as sometimes check the returned values. In order to be able to
>>> switch from a 1 byte status register to a 2 bytes status register while
>>> keeping the same level of verification, let's introduce a new helper
>>> that writes them both (atomically) and then reads them back (separated)
>>> to compare the values.
>>>
>>> In case 2 bytes registers are not supported, we still have the usual
>>> fallback available in the helper being exported to the rest of the core.
>>>
>>> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
>>
>> I'm confused. Doesn't spi_nor_write_16bit_sr_and_check() do the same
>> thing? How are these two different?
>
> So I've never come around to finish reviewing this series due to
> personal reasons, but here are my remarks. Personally, I really
> don't like all these multiple helpers doing almost the same thing.
> But it is what is is for now.
>
> Back when reviewing this series, I've digged into this and it mostly
> evolve around how to enable the QE bit, that is defined in the 15th
> SFDP DWORD. One could see how we could consolidate all the status
> register handling in one function which are then called by the
> different (specified) quad_enable helpers.

I already had a look, it doesn't seem so straightforward. But I will
look into it deeper, I am willing to improve things. There will anyway
be a wide variety of helpers because there is a wide variety of QER
possibilities. What we can do though, is to decouple status register
writing and QE bit masking.

However, I would like to point that this is totally orthogonal to the
whole (almost 30 patch long) locking cleanup and CMP feature series, so
I do not plan to change this particular implementation in
v5. Reorganising these helpers should be done in its own follow-up
series.

Thanks,
Miquèl