Re: [virtio-comment] Re: [PATCH] [PATCH v5] virtio-spi: add the device specification

[Cornelia Huck <cohuck@redhat.com>]

On Mon, Nov 27 2023, Cornelia Huck <cohuck@redhat.com> wrote:

> On Mon, Nov 27 2023, Haixu Cui <quic_haixcui@quicinc.com> wrote:
>
>> On 11/24/2023 11:46 PM, Cornelia Huck wrote:
>>> On Fri, Nov 24 2023, Haixu Cui <quic_haixcui@quicinc.com> wrote:
>>>> +The \field{chip_select_max_number} is the maximum number of chipselect the host SPI controller supports.
>>> 
>>> "chipselect" is probably a known term for people familiar with SPI -- is
>>> there any definition of those terms that the spec can point to?
>>
>> Just as Mark said, there is no formal spec for SPI, so no standard spec 
>> for such terms referring to. The same for CPHA/CPOL/LSB/MSB, please see 
>> below.
>
> If we have nothing to point to, it is probably best to simply
> expand/explain the terms on their first usage.
>
>>> Can we point to some documentation that explains CPHA and CPOL?
>>
>> Here. No standard SPI spec to point to. CPOL/CPHA have definitions in 
>> wikipedia(Clock polarity and phase chapter):
>>
>> https://en.wikipedia.org/wiki/Serial_Peripheral_Interface
>>
>> How about copying some concise information from wikipedia as Note? Or is 
>> referring to such webpage acceptable in this spec.
>
> Not sure if we can do an outright copy (licence compatibility), but
> paraphrasing should be fine. (I'd rather not directly reference the
> site, because the content is not guaranteed to be stable, but we could
> maybe add it as "further reading".)

Looking again, the kernel doc referenced by Mark
(https://www.kernel.org/doc/html/v6.6/driver-api/spi.html) might also be
a good candidate, especially as we can refer to a specific version.