linux-kernel - Re: [PATCH 06/17] dt-bindings: net: mscc-miim: Add resets property

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Message-ID: <20240503162148.1dc64b9a@bootlin.com>
Date: Fri, 3 May 2024 16:21:48 +0200
From: Herve Codina <herve.codina@...tlin.com>
To: Alexandre Belloni <alexandre.belloni@...tlin.com>
Cc: Andrew Lunn <andrew@...n.ch>, Conor Dooley <conor.dooley@...rochip.com>,
 Thomas Gleixner <tglx@...utronix.de>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, "David S. Miller" <davem@...emloft.net>, Eric
 Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo
 Abeni <pabeni@...hat.com>, Lee Jones <lee@...nel.org>, Arnd Bergmann
 <arnd@...db.de>, Horatiu Vultur <horatiu.vultur@...rochip.com>,
 UNGLinuxDriver@...rochip.com, Heiner Kallweit <hkallweit1@...il.com>,
 Russell King <linux@...linux.org.uk>, Saravana Kannan
 <saravanak@...gle.com>, Bjorn Helgaas <bhelgaas@...gle.com>, Philipp Zabel
 <p.zabel@...gutronix.de>, Lars Povlsen <lars.povlsen@...rochip.com>, Steen
 Hegelund <Steen.Hegelund@...rochip.com>, Daniel Machon
 <daniel.machon@...rochip.com>, linux-kernel@...r.kernel.org,
 devicetree@...r.kernel.org, netdev@...r.kernel.org,
 linux-pci@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, Allan
 Nielsen <allan.nielsen@...rochip.com>, Luca Ceresoli
 <luca.ceresoli@...tlin.com>, Thomas Petazzoni
 <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH 06/17] dt-bindings: net: mscc-miim: Add resets property

Hi,

On Thu, 2 May 2024 15:22:09 +0200
Alexandre Belloni <alexandre.belloni@...tlin.com> wrote:

> On 02/05/2024 14:26:36+0200, Andrew Lunn wrote:
> > On Thu, May 02, 2024 at 11:31:00AM +0100, Conor Dooley wrote:  
> > > On Thu, May 02, 2024 at 11:50:43AM +0200, Herve Codina wrote:  
> > > > Hi Andrew,
> > > > 
> > > > On Tue, 30 Apr 2024 18:31:46 +0200
> > > > Andrew Lunn <andrew@...n.ch> wrote:
> > > >   
> > > > > > We have the same construction with the pinctrl driver used in the LAN966x
> > > > > >   Documentation/devicetree/bindings/pinctrl/mscc,ocelot-pinctrl.yaml
> > > > > > 
> > > > > > The reset name is 'switch' in the pinctrl binding.
> > > > > > I can use the same description here as the one present in the pinctrl binding:
> > > > > >   description: Optional shared switch reset.
> > > > > > and keep 'switch' as reset name here (consistent with pinctrl reset name).
> > > > > > 
> > > > > > What do you think about that ?    
> > > > > 
> > > > > It would be good to document what it is shared with. So it seems to be
> > > > > the switch itself, pinctl and MDIO? Anything else?
> > > > >   
> > > > 
> > > > To be honest, I know that the GPIO controller (microchip,sparx5-sgpio) is
> > > > impacted but I don't know if anything else is impacted by this reset.
> > > > I can update the description with:
> > > >   description:
> > > >     Optional shared switch reset.
> > > >     This reset is shared with at least pinctrl, GPIO, MDIO and the switch
> > > >     itself.
> > > > 
> > > > Does it sound better ?  
> > > 
> > > $dayjob hat off, bindings hat on: If you don't know, can we get someone
> > > from Microchip (there's some and a list in CC) to figure it out?  
> > 
> > That is probably a good idea, there is potential for hard to find bugs
> > here, when a device gets an unexpected reset. Change the order things
> > probe, or an unexpected EPRODE_DEFER could be interesting.
> >   
> 
> 
> The datasheet states:
> "The VCore system comprises all the blocks attached to the VCore Shared
> Bus (SBA), including the PCIe, DDR, frame DMA, SI slave, and MIIM slave
> blocks. The device includes all the blocks attached to the Switch Core
> Register Bus (CSR) including the VRAP slave. For more information about
> the VCore System blocks, see Figure 5-1."
> 
> However, the reset driver protects the VCORE itself by setting bit 5.
> Everything else is going to be reset.
> 

Right,
I will update the reset description with:
  description:
    Optional shared switch reset.
    This reset is shared with all blocks attached to the Switch Core Register
    Bus (CSR) including VRAP slave.

Is that better ?

Best regards,
Hervé
-- 
Hervé Codina, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com