From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
To: Vladimir Oltean <olteanv@gmail.com>
Cc: Colin Foster <colin.foster@in-advantage.com>,
linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org,
devicetree@vger.kernel.org, netdev@vger.kernel.org,
Russell King <linux@armlinux.org.uk>,
Linus Walleij <linus.walleij@linaro.org>,
UNGLinuxDriver@microchip.com,
Alexandre Belloni <alexandre.belloni@bootlin.com>,
Claudiu Manoil <claudiu.manoil@nxp.com>,
Lee Jones <lee@kernel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
Rob Herring <robh+dt@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Jakub Kicinski <kuba@kernel.org>,
Eric Dumazet <edumazet@google.com>,
"David S. Miller" <davem@davemloft.net>,
Florian Fainelli <f.fainelli@gmail.com>,
Vivien Didelot <vivien.didelot@gmail.com>,
Andrew Lunn <andrew@lunn.ch>
Subject: Re: [PATCH v3 net-next 12/14] dt-bindings: net: dsa: ocelot: add ocelot-ext documentation
Date: Wed, 5 Oct 2022 10:09:06 +0200 [thread overview]
Message-ID: <cae8e149-ef1e-66c6-20f5-067e3fd8c586@linaro.org> (raw)
In-Reply-To: <20221004160135.lqugs6cf5b7fwkxq@skbuf>
On 04/10/2022 18:01, Vladimir Oltean wrote:
> On Tue, Oct 04, 2022 at 04:59:02PM +0200, Krzysztof Kozlowski wrote:
>> On 04/10/2022 14:15, Vladimir Oltean wrote:
>>> On Tue, Oct 04, 2022 at 01:19:33PM +0200, Krzysztof Kozlowski wrote:
>>>>> + # Ocelot-ext VSC7512
>>>>> + - |
>>>>> + spi {
>>>>> + soc@0 {
>>>>
>>>> soc in spi is a bit confusing.
>>>
>>> Do you have a better suggestion for a node name? This is effectively a
>>> container for peripherals which would otherwise live under a /soc node,
>>
>> /soc node implies it does not live under /spi node. Otherwise it would
>> be /spi/soc, right?
>
> Did you read what's written right below? I can explain if you want, but
> there's no point if you're not going to read or ask other clarification
> questions.
>
>>> if they were accessed over MMIO by the internal microprocessor of the
>>> SoC, rather than by an external processor over SPI.
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> The /spi/soc@0 node actually has a compatible of "mscc,vsc7512" which
> Colin did not show in the example (it is not "simple-bus"). It is covered
> by Documentation/devicetree/bindings/mfd/mscc,ocelot.yaml. Still waiting
> for a better suggestion for how to name the mfd container node.
Then still the /spi node does not seem related. If I understand
correctly, your device described in this bindings is a child of soc@0.
Sounds fine. How that soc@0 is connected to the parent - via SPI or
whatever - is not related to this binding, is it? It is related to the
soc binding, but not here.
>
>>>> How is this example different than previous one (existing soc example)?
>>>> If by compatible and number of ports, then there is no much value here.
>>>
>>> The positioning relative to the other nodes is what's different.
>>
>> Positioning of nodes is not worth another example, if everything else is
>> the same. What is here exactly tested or shown by example? Using a
>> device in SPI controller?
>
> Everything is not the same, it is not the same hardware as what is currenly
> covered by Documentation/devicetree/bindings/net/dsa/mscc,ocelot.yaml.
> The "existing soc example" (mscc,vsc9953-switch) has a different port
> count, integration with a different SERDES, interrupt controller, pin
> controller, things like that. The examples already differ in port count
> and phy-mode values, I expect they will start diverging more in the
> future. If you still believe it's not worth having an example of how to
> instantiate a SPI-controlled VSC7512 because there also exists an
> example of an MMIO-controlled VSC9953, then what can I say.
>
> ------ cut here ------
>
> Unrelated to your "existing soc example" (the VSC9953), but relevant and
> you may want to share your opinion on this:
>
> The same hardware present in the VSC7514 SoC can also be driven by an
> integrated MIPS processor, and in that case, it is indeed expected that
> the same dt-bindings cover both the /soc and the /spi/soc@0/ relative
> positioning of their OF node. This is true for simpler peripherals like
> "mscc,ocelot-miim", "mscc,ocelot-pinctrl", "mscc,ocelot-sgpio". However
> it is not true for the main switching IP of the SoC itself.
>
> When driven by a switchdev driver, by the internal MIPS processor (the
> DMA engine is what is used for packet I/O), the switching IP follows the
> Documentation/devicetree/bindings/net/mscc,vsc7514-switch.yaml binding
> document.
>
> When driven by a DSA driver (external processor, host frames are
> redirected through an Ethernet port instead of DMA controller),
> the switching IP follows the Documentation/devicetree/bindings/net/dsa/mscc,ocelot.yaml
> document.
>
> The switching IP is special in this regard because the hardware is not
> used in the same way. The DSA dt-binding also needs the 'ethernet'
> phandle to be present in a port node. The different placement of the
> bindings according to the use case of the hardware is a bit awkward, but
> is a direct consequence of the separation between DSA and pure switchdev
> drivers that has existed thus far (and the fact that DSA has its own
> folder in the dt-bindings, with common properties in dsa.yaml and
> dsa-port.yaml etc). It is relatively uncommon for a switching IP to have
> provisioning to be used in both modes, and for Linux to support both
> modes (using different drivers), yet this is what we have here.
Is there a question here to me? What shall I do with this paragraph? You
know, I do not have a problem of lack of material to read...
Best regards,
Krzysztof
next prev parent reply other threads:[~2022-10-05 8:09 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-26 0:29 [PATCH v3 net-next 00/14] add support for the the vsc7512 internal copper phys Colin Foster
2022-09-26 0:29 ` [PATCH v3 net-next 01/14] net: mscc: ocelot: expose ocelot wm functions Colin Foster
2022-09-26 0:29 ` [PATCH v3 net-next 02/14] net: mscc: ocelot: expose regfield definition to be used by other drivers Colin Foster
2022-09-26 0:29 ` [PATCH v3 net-next 03/14] net: mscc: ocelot: expose stats layout " Colin Foster
2022-09-26 0:29 ` [PATCH v3 net-next 04/14] net: mscc: ocelot: expose vcap_props structure Colin Foster
2022-09-26 0:29 ` [PATCH v3 net-next 05/14] net: mscc: ocelot: expose ocelot_reset routine Colin Foster
2022-09-26 0:29 ` [PATCH v3 net-next 06/14] net: dsa: felix: add configurable device quirks Colin Foster
2022-09-26 0:29 ` [PATCH v3 net-next 07/14] net: dsa: felix: populate mac_capabilities for all ports Colin Foster
2022-09-26 0:29 ` [PATCH v3 net-next 08/14] net: dsa: felix: update init_regmap to be string-based Colin Foster
2022-09-27 17:53 ` Vladimir Oltean
2022-09-27 18:43 ` Colin Foster
2022-09-27 18:56 ` Vladimir Oltean
2022-09-26 0:29 ` [PATCH v3 net-next 09/14] pinctrl: ocelot: avoid macro redefinition Colin Foster
2022-09-26 0:29 ` [PATCH v3 net-next 10/14] mfd: ocelot: prepend resource size macros to be 32-bit Colin Foster
2022-09-26 0:29 ` [PATCH v3 net-next 11/14] mfd: ocelot: add regmaps for ocelot_ext Colin Foster
2022-09-27 21:04 ` Vladimir Oltean
2022-09-27 23:01 ` Colin Foster
2022-09-26 0:29 ` [PATCH v3 net-next 12/14] dt-bindings: net: dsa: ocelot: add ocelot-ext documentation Colin Foster
2022-09-27 20:26 ` Vladimir Oltean
2022-09-27 22:20 ` Colin Foster
2022-10-07 22:48 ` Vladimir Oltean
2022-10-08 17:56 ` Colin Foster
2022-09-30 21:15 ` Colin Foster
2022-10-01 0:20 ` Colin Foster
2022-10-03 15:28 ` Vladimir Oltean
2022-10-07 20:44 ` Colin Foster
2022-10-07 22:38 ` Vladimir Oltean
2022-10-04 11:19 ` Krzysztof Kozlowski
2022-10-04 12:15 ` Vladimir Oltean
2022-10-04 14:59 ` Krzysztof Kozlowski
2022-10-04 16:01 ` Vladimir Oltean
2022-10-05 8:09 ` Krzysztof Kozlowski [this message]
2022-10-07 23:10 ` Vladimir Oltean
2022-10-09 15:49 ` Krzysztof Kozlowski
2022-10-05 0:08 ` Colin Foster
2022-10-05 8:03 ` Krzysztof Kozlowski
2022-10-05 15:44 ` Colin Foster
2022-10-05 16:09 ` Krzysztof Kozlowski
2022-10-08 0:00 ` Vladimir Oltean
2022-10-09 16:14 ` Krzysztof Kozlowski
2022-10-10 13:07 ` Vladimir Oltean
2022-10-10 13:37 ` Krzysztof Kozlowski
2022-10-10 17:48 ` Vladimir Oltean
2022-10-10 18:47 ` Colin Foster
2022-10-10 19:11 ` Vladimir Oltean
2022-10-11 9:53 ` Vladimir Oltean
2023-01-18 22:28 ` Colin Foster
2023-01-19 20:21 ` Vladimir Oltean
2023-01-20 18:16 ` Colin Foster
2022-09-26 0:29 ` [PATCH v3 net-next 13/14] net: dsa: ocelot: add external ocelot switch control Colin Foster
2022-09-27 20:40 ` Vladimir Oltean
2022-09-26 0:29 ` [PATCH v3 net-next 14/14] mfd: " Colin Foster
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