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

From: Heiko Stuebner <[email-masked]>
Date: Sun, 08 May 2022 11:41:48 +0200

Am Sonntag, 8. Mai 2022, 08:24:37 CEST schrieb Frank Wunderlich:
> Am 7. Mai 2022 22:01:22 MESZ schrieb Krzysztof Kozlowski <[email-masked]>:
> >On 07/05/2022 19:04, Frank Wunderlich wrote:
> >> From: Frank Wunderlich <[email-masked]>
> >> 
> >> 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.

Heiko

> >> 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."
> 
> regards Frank
>