Aw: Re: [PATCH v3 5/6] dt-bindings: net: dsa: make reset optional and add rgmii-mode to mt7531

Hi Heiko

Gesendet: Sonntag, 08. Mai 2022 um 11:41 Uhr
Von: "Heiko Stuebner" [off-list ref]
Am Sonntag, 8. Mai 2022, 08:24:37 CEST schrieb Frank Wunderlich:

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Am 7. Mai 2022 22:01:22 MESZ schrieb Krzysztof Kozlowski [off-list ref]:

quoted

On 07/05/2022 19:04, Frank Wunderlich wrote:

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From: Frank Wunderlich <redacted>

Make reset optional as driver already supports it,

I do not see the connection between hardware needing or not needing a
reset GPIO and a driver supporting it or not... What does it mean?

My board has a shared gpio-reset between gmac and switch, so both will resetted if it
is asserted. Currently it is set to the gmac and is aquired exclusive. Adding it to switch results in 2 problems:

- due to exclusive and already mapped to gmac, switch driver exits as it cannot get the reset-gpio again.
- if i drop the reset from gmac and add to switch, it resets the gmac and this takes too long for switch
to get up. Of course i can increase the wait time after reset,but dropping reset here was the easier way.

Using reset only on gmac side brings the switch up.

I think the issue is more for the description itself.

Devicetree is only meant to describe the hardware and does in general don't
care how any firmware (Linux-kernel, *BSD, etc) handles it. So going with
"the kernel does it this way" is not a valid reason for a binding change ;-) .

Instead in general want to reason that there are boards without this reset
facility and thus make it optional for those.

if only the wording is the problem i try to rephrase it from hardware PoV.

maybe something like this?

https://github.com/frank-w/BPI-R2-4.14/commits/5.18-mt7531-mainline2/Documentation/devicetree/bindings/net/dsa/mediatek%2Cmt7530.yaml

Another way is maybe increasing the delay after the reset (to give more time all
come up again), but imho it is no good idea resetting the gmac/mdio-bus from the
child device.

have not looked into the gmac driver if this always  does the initial reset to
have a "clean state". In this initial reset the switch will be resetted too
and does not need an additional one which needs the gmac/mdio initialization
to be done again.

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allow port 5 as
cpu-port

How do you allow it here?

Argh, seems i accidentally removed this part and have not recognized while checking :(

It should only change description of reg for ports to:

"Port address described must be 5 or 6 for CPU port and from 0 to 5 for user ports."

noticed that the target-phase is not removed but squashed in the first bindings-patch.
This was a rebasing error and not intented...will fix in next version.

regards Frank

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