Re: [PATCH v2 0/3] gpio: 74HC595 / 74x164 shift register improvements

Re: [PATCH v2 0/3] gpio: 74HC595 / 74x164 shift register improvements

[Geert Uytterhoeven]

Hi Bartosz,

CC spi

On Fri, Jan 3, 2025 at 9:33 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
>
> On Tue, 24 Dec 2024 09:02:09 +0100, J. Neuschäfer wrote:
> > This patchset adds a compatible string for another part, and clarifies
> > the role of the latch clock pin on 74x164-compatible shift registers.
>
> Applied, thanks!
>
> [1/3] dt-bindings: gpio: fairchild,74hc595: Add On Semi MC74HC595A compat
>       commit: 0ba6cec7acbb666d28998780683deb83a3e677e3
> [2/3] gpio: 74x164: Add On Semi MC74HC595A compat
>       commit: b1468db9d865deb5271c9a20d05201b1c0636895

Do we really need to document and add driver support for all variants?
I can easily come up with a list of tens or perhaps even hundreds
of xx74yy595z parts that are all compatible, as far as software is
concerned.  As SPI was invented by Motorola, the original part is
probably named MC74595 or MC74LS595 (yes, ON Semiconductor bought the
logic division of Motorola).

Perhaps we need a separate vendor prefix for the 74xx-series[1]?
The xx-prefix and z-suffix don't matter; the yy-infix for semiconductor
technology rarely matters (there are a few exceptions, though, mostly
pinout, which doesn't matter for software).

Thanks!

[1] https://en.wikipedia.org/wiki/List_of_7400-series_integrated_circuits

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH v2 0/3] gpio: 74HC595 / 74x164 shift register improvements

[Bartosz Golaszewski]

On Mon, Jan 6, 2025 at 10:19 AM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
>
> Hi Bartosz,
>
> CC spi
>
> On Fri, Jan 3, 2025 at 9:33 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:
> > From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> >
> > On Tue, 24 Dec 2024 09:02:09 +0100, J. Neuschäfer wrote:
> > > This patchset adds a compatible string for another part, and clarifies
> > > the role of the latch clock pin on 74x164-compatible shift registers.
> >
> > Applied, thanks!
> >
> > [1/3] dt-bindings: gpio: fairchild,74hc595: Add On Semi MC74HC595A compat
> >       commit: 0ba6cec7acbb666d28998780683deb83a3e677e3
> > [2/3] gpio: 74x164: Add On Semi MC74HC595A compat
> >       commit: b1468db9d865deb5271c9a20d05201b1c0636895
>
> Do we really need to document and add driver support for all variants?
> I can easily come up with a list of tens or perhaps even hundreds
> of xx74yy595z parts that are all compatible, as far as software is
> concerned.  As SPI was invented by Motorola, the original part is
> probably named MC74595 or MC74LS595 (yes, ON Semiconductor bought the
> logic division of Motorola).
>
> Perhaps we need a separate vendor prefix for the 74xx-series[1]?
> The xx-prefix and z-suffix don't matter; the yy-infix for semiconductor
> technology rarely matters (there are a few exceptions, though, mostly
> pinout, which doesn't matter for software).
>

I missed the fact that Rob actually responded to patch 1/3 with a
similar suggestion (fallback, instead of a full compatible).

I can drop this series from my queue if it needs more rework.

Bartosz

Re: [PATCH v2 0/3] gpio: 74HC595 / 74x164 shift register improvements

[Csókás Bence]

Hi all,

On 2025. 01. 06. 21:16, Bartosz Golaszewski wrote:
> On Mon, Jan 6, 2025 at 10:19 AM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
>> Do we really need to document and add driver support for all variants?
>> I can easily come up with a list of tens or perhaps even hundreds
>> of xx74yy595z parts that are all compatible, as far as software is
>> concerned.  As SPI was invented by Motorola, the original part is
>> probably named MC74595 or MC74LS595 (yes, ON Semiconductor bought the
>> logic division of Motorola).

I second this, no point of having a new compatible which is a guaranteed 
1:1 equivalent of an already existing one. Especially true if the only 
change was that a different company bought the IP. By the same logic, I 
could start to sumbit patches to change all `fsl,` compatible-s to 
`nxp,`; `atmel,`, `maxim,`, `smsc,` etc. to `microchip,`; `ralink,` to 
`mediatek,` and so on. There would be no end.

>> Perhaps we need a separate vendor prefix for the 74xx-series[1]?

I don't think that is the case. Rather, we should document that the 
existing binding/compatible should be used for all such simple cases (it 
is called _compatible_ for a reason, after all, and not 
`exact-part-number`).

>> The xx-prefix and z-suffix don't matter; the yy-infix for semiconductor
>> technology rarely matters (there are a few exceptions, though, mostly
>> pinout, which doesn't matter for software).
>>
> 
> I missed the fact that Rob actually responded to patch 1/3 with a
> similar suggestion (fallback, instead of a full compatible).
> 
> I can drop this series from my queue if it needs more rework.

I think you can keep 3/3 (the one commenting the use of `latch` as CS). 
The rest can be replaced by another commit commenting on what it means 
to be `fairchild,74hc595`:

* tri-state output
* 8-bit output
* OE pin (or latch or whatever it happens to be called in their chosen 
manufacturer's datasheet)
* SRCLR does not seem to be used by the driver, so we can probably skip 
that...

And telling people NOT to add a new compatible if their part satisfies 
these.

Bence

Re: [PATCH v2 0/3] gpio: 74HC595 / 74x164 shift register improvements

[Bartosz Golaszewski]

On Wed, Jan 8, 2025 at 11:26 AM Csókás Bence <csokas.bence@prolan.hu> wrote:
>
> Hi all,
>
> On 2025. 01. 06. 21:16, Bartosz Golaszewski wrote:
> > On Mon, Jan 6, 2025 at 10:19 AM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> >> Do we really need to document and add driver support for all variants?
> >> I can easily come up with a list of tens or perhaps even hundreds
> >> of xx74yy595z parts that are all compatible, as far as software is
> >> concerned.  As SPI was invented by Motorola, the original part is
> >> probably named MC74595 or MC74LS595 (yes, ON Semiconductor bought the
> >> logic division of Motorola).
>
> I second this, no point of having a new compatible which is a guaranteed
> 1:1 equivalent of an already existing one. Especially true if the only
> change was that a different company bought the IP. By the same logic, I
> could start to sumbit patches to change all `fsl,` compatible-s to
> `nxp,`; `atmel,`, `maxim,`, `smsc,` etc. to `microchip,`; `ralink,` to
> `mediatek,` and so on. There would be no end.
>
> >> Perhaps we need a separate vendor prefix for the 74xx-series[1]?
>
> I don't think that is the case. Rather, we should document that the
> existing binding/compatible should be used for all such simple cases (it
> is called _compatible_ for a reason, after all, and not
> `exact-part-number`).
>
> >> The xx-prefix and z-suffix don't matter; the yy-infix for semiconductor
> >> technology rarely matters (there are a few exceptions, though, mostly
> >> pinout, which doesn't matter for software).
> >>
> >
> > I missed the fact that Rob actually responded to patch 1/3 with a
> > similar suggestion (fallback, instead of a full compatible).
> >
> > I can drop this series from my queue if it needs more rework.
>
> I think you can keep 3/3 (the one commenting the use of `latch` as CS).
> The rest can be replaced by another commit commenting on what it means
> to be `fairchild,74hc595`:
>

J. Neuschäfer: do you want to send a follow-up for this?

Bart

> * tri-state output
> * 8-bit output
> * OE pin (or latch or whatever it happens to be called in their chosen
> manufacturer's datasheet)
> * SRCLR does not seem to be used by the driver, so we can probably skip
> that...
>
> And telling people NOT to add a new compatible if their part satisfies
> these.
>

Re: [PATCH v2 0/3] gpio: 74HC595 / 74x164 shift register improvements

[J. Neuschäfer]

On Wed, Jan 08, 2025 at 01:08:37PM +0100, Bartosz Golaszewski wrote:
> On Wed, Jan 8, 2025 at 11:26 AM Csókás Bence <csokas.bence@prolan.hu> wrote:
> >
> > Hi all,

Hi,


> >
> > On 2025. 01. 06. 21:16, Bartosz Golaszewski wrote:
> > > On Mon, Jan 6, 2025 at 10:19 AM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > >> Do we really need to document and add driver support for all variants?
> > >> I can easily come up with a list of tens or perhaps even hundreds
> > >> of xx74yy595z parts that are all compatible, as far as software is
> > >> concerned.  As SPI was invented by Motorola, the original part is
> > >> probably named MC74595 or MC74LS595 (yes, ON Semiconductor bought the
> > >> logic division of Motorola).
> >
> > I second this, no point of having a new compatible which is a guaranteed
> > 1:1 equivalent of an already existing one. Especially true if the only
> > change was that a different company bought the IP. By the same logic, I
> > could start to sumbit patches to change all `fsl,` compatible-s to
> > `nxp,`; `atmel,`, `maxim,`, `smsc,` etc. to `microchip,`; `ralink,` to
> > `mediatek,` and so on. There would be no end.
> >
> > >> Perhaps we need a separate vendor prefix for the 74xx-series[1]?
> >
> > I don't think that is the case. Rather, we should document that the
> > existing binding/compatible should be used for all such simple cases (it
> > is called _compatible_ for a reason, after all, and not
> > `exact-part-number`).
> >
> > >> The xx-prefix and z-suffix don't matter; the yy-infix for semiconductor
> > >> technology rarely matters (there are a few exceptions, though, mostly
> > >> pinout, which doesn't matter for software).
> > >>
> > >
> > > I missed the fact that Rob actually responded to patch 1/3 with a
> > > similar suggestion (fallback, instead of a full compatible).
> > >
> > > I can drop this series from my queue if it needs more rework.
> >
> > I think you can keep 3/3 (the one commenting the use of `latch` as CS).
> > The rest can be replaced by another commit commenting on what it means
> > to be `fairchild,74hc595`:
> >
> 
> J. Neuschäfer: do you want to send a follow-up for this?

I'm fine with this outcome, but I'd prefer not to prepare this proposed
patch (for reasons of time management on my end, mostly).  So if anyone
else would take it up, I'd greatly appreciate that.


Best regards,
 jn