netdev - Re: [PATCH] tg3: Add param `short_preamble` to enable MDIO traffic to external PHYs

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Message-ID: <d254d820-399d-4ac7-b9b0-e4b3668bbed3@lunn.ch>
Date: Sat, 3 Aug 2024 01:34:58 +0200
From: Andrew Lunn <andrew@...n.ch>
To: Michael Chan <michael.chan@...adcom.com>
Cc: Paul Menzel <pmenzel@...gen.mpg.de>,
	Pavan Chebbi <pavan.chebbi@...adcom.com>,
	Michael Chan <mchan@...adcom.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Roy Lee <roy_lee@...ton.com>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tg3: Add param `short_preamble` to enable MDIO traffic
 to external PHYs

On Fri, Aug 02, 2024 at 12:51:15PM -0700, Michael Chan wrote:
> On Fri, Aug 2, 2024 at 3:05 AM Paul Menzel <pmenzel@...gen.mpg.de> wrote:
> 
> > diff --git a/drivers/net/ethernet/broadcom/tg3.c b/drivers/net/ethernet/broadcom/tg3.c
> > index 0ec5f01551f9..9b4ab201fd9a 100644
> > --- a/drivers/net/ethernet/broadcom/tg3.c
> > +++ b/drivers/net/ethernet/broadcom/tg3.c
> > @@ -233,6 +233,10 @@ static int tg3_debug = -1; /* -1 == use TG3_DEF_MSG_ENABLE as value */
> >  module_param(tg3_debug, int, 0);
> >  MODULE_PARM_DESC(tg3_debug, "Tigon3 bitmapped debugging message enable value");
> >
> > +static int short_preamble = 0;
> > +module_param(short_preamble, int, 0);
> > +MODULE_PARM_DESC(short_preamble, "Enable short preamble.");
> > +
> 
> Module parameters are generally not accepted.  If this is something
> other devices can potentially use, it's better to use a more common
> interface.

+1

Most systems supporting suppressed preamble do this using the DT
property 'suppress-preamble'. See:

Documentation/devicetree/bindings/net/mdio.yaml

You could add an ACPI parameter for x86. You could also consider
implementing clock-frequency if the MDIO bus master and all the
devices on the bus support faster than 2.5MHz.

	Andrew