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

[Michael Chan]

On Fri, Aug 2, 2024 at 1:55 PM Paul Menzel <pmenzel@xxxxxxxxxxxxx> wrote:
>
> >> +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.
>
> I saw the patch in the SONiC repository and took a shot at upstreaming
> it. `tg.h` defines the macro:
>
>      #define  MAC_MI_MODE_SHORT_PREAMBLE  0x00000002
>
> Any idea how this should be used? Can it be enabled unconditionally? I
> do not even have the datasheet.
>

Here's the programmer's reference:

https://docs.broadcom.com/doc/571X-5720-PG1XX

But there is not much additional information about the SHORT_PREAMBLE
bit.  I will need to ask internally about this bit.  Thanks.

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