Re: [PATCH RFC v6 2/6] dpll: Add DPLL framework base functions

Jiri Pirko
2023-05-10T06:17:38Z

Tue, May 09, 2023 at 07:53:02PM CEST, kuba@kernel.org wrote:
>On Tue, 9 May 2023 17:21:42 +0200 Jiri Pirko wrote:
>> Tue, May 09, 2023 at 04:52:47PM CEST, kuba@kernel.org wrote:
>> >On Tue, 9 May 2023 09:53:07 +0200 Jiri Pirko wrote:
>> >> >Yup. Even renaming EXT to something that's less.. relative :(
>> >>
>> >> Suggestion?
>> >
>> >Well, is an SMT socket on the board an EXT pin?
>> >Which is why I prefer PANEL.
>>
>> Makes sense.
>> To speak code, we'll have:
>>
>> /**
>> * enum dpll_pin_type - defines possible types of a pin, valid values for
>> * DPLL_A_PIN_TYPE attribute
>> * @DPLL_PIN_TYPE_UNSPEC: unspecified value
>> * @DPLL_PIN_TYPE_MUX: aggregates another layer of selectable pins
>> * @DPLL_PIN_TYPE_PANEL: physically facing user, for example on a front panel
>> * @DPLL_PIN_TYPE_SYNCE_ETH_PORT: ethernet port PHY's recovered clock
>> * @DPLL_PIN_TYPE_INT_OSCILLATOR: device internal oscillator
>> * @DPLL_PIN_TYPE_GNSS: GNSS recovered clock
>> */
>> enum dpll_pin_type {
>> DPLL_PIN_TYPE_UNSPEC,
>> DPLL_PIN_TYPE_MUX,
>> DPLL_PIN_TYPE_PANEL,
>> DPLL_PIN_TYPE_SYNCE_ETH_PORT,
>> DPLL_PIN_TYPE_INT_OSCILLATOR,
>> DPLL_PIN_TYPE_GNSS,
>>
>> __DPLL_PIN_TYPE_MAX,
>> DPLL_PIN_TYPE_MAX = (__DPLL_PIN_TYPE_MAX - 1)
>> };
>
>Maybe we can keep the EXT here, just not in the label itself.
>Don't think we care to add pin type for PANEL vs SMT vs jumper?

Okay:
enum dpll_pin_type {
DPLL_PIN_TYPE_UNSPEC,
DPLL_PIN_TYPE_MUX,
DPLL_PIN_TYPE_EXT,
DPLL_PIN_TYPE_SYNCE_ETH_PORT,
DPLL_PIN_TYPE_INT_OSCILLATOR,
DPLL_PIN_TYPE_GNSS,

__DPLL_PIN_TYPE_MAX,
DPLL_PIN_TYPE_MAX = (__DPLL_PIN_TYPE_MAX - 1)
};

>
>> >> Sure, I get what you say and agree. I'm just trying to find out the
>> >> actual attributes :)
>> >
>> >PANEL label must match the name on the panel. User can take the card
>> >into their hand, look at the front, and there should be a label/sticker/
>> >/engraving which matches exactly what the kernel reports.
>> >
>> >If the label is printed on the board it's a BOARD_LABEL, if it's the
>> >name of a trace in board docs it's a BOARD_TRACE, if it's a pin of
>> >the ASIC it's a PACKAGE_PIN.
>> >
>> >If it's none of those, or user does not have access to the detailed
>> >board / pinout - don't use the label.
>>
>> To speak code, we'll have:
>> DPLL_A_PIN_PANEL_LABEL (string)
>> available always when attr[DPLL_A_PIN_TYPE] == DPLL_PIN_TYPE_PANEL
>
>Not sure about always, if there's only one maybe there's no need
>to provide the label?

Well, I would like to have check in pin_register() for this. That would
be non-trivial if this would be required only in case pin_count>1.
However I can imagine a card with one connector without any label on it.
IDK.

>
>> DPLL_A_PIN_BOARD_LABEL (string)
>> may be available for any type, optional
>> DPLL_A_PIN_BOARD_TRACE (string)
>> may be available for any type, optional
>> DPLL_A_PIN_PACKAGE_PIN (string)
>> may be available for any type, optional
>>
>> Makes sense?
>
>yup (obviously we need to document the semantics)

Agreed.

>
>> But this does not prevent driver developer to pack random crap in the
>> string anyway :/
>
>It doesn't but it hopefully makes it much more likely that (1) reviewer
>will notice that something is off if the driver printfs random crap;
>and (2) that the user reading the documentation will complain that
>e.g.BOARD_LABEL is used but does not match the label on they see...

Fair.