[U-Boot] Query: Ethernet switch support

[U-Boot] Query: Ethernet switch support

[Sharma Bhupesh-B45370]

Hi List,

I am trying to add support of a Vitesse L2 switch in u-boot (in unmanaged configuration).
I was analyzing whether advanced features like flow control, link-aggregation etc are
required to be supported for a L2 switch  working in a u-boot bootloader level.

My point-of-view is that the L2 switch, should support only bare-minimum
tftp of images, ping to other ethernet entities, bootp .. 
type of commands on u-boot and as such the L2 switch u-boot driver 
doesn't need to address flow-control and other such advanced features (probably
of interest for a Linux device driver).

But, I am not sure about the design approaches used to support 
previous switch modules in u-boot.

Also I had a query whether there is a common switch framework in-place/under-consideration
in u-boot, similar to what is already present in OpenWrt code:
https://dev.openwrt.org/browser/trunk/package/boot/uboot-lantiq/patches/0019-net-switchlib-add-framework-for-ethernet-switch-driv.patch?rev=35292

Would porting this to u-boot make sense to have a common framework for ethernet switch
in-place?

Can you please let me know your views on the same and point me to any 
reference switch drivers that support these features.

Regards,
Bhupesh

[U-Boot] Query: Ethernet switch support

[Albert ARIBAUD]

Hi Sharma,

On Mon, 29 Jul 2013 15:33:39 +0000, Sharma Bhupesh-B45370
<B45370@freescale.com> wrote:

> Hi List,
> 
> I am trying to add support of a Vitesse L2 switch in u-boot (in unmanaged configuration).
> I was analyzing whether advanced features like flow control, link-aggregation etc are
> required to be supported for a L2 switch  working in a u-boot bootloader level.
> 
> My point-of-view is that the L2 switch, should support only bare-minimum
> tftp of images, ping to other ethernet entities, bootp .. 
> type of commands on u-boot and as such the L2 switch u-boot driver 
> doesn't need to address flow-control and other such advanced features (probably
> of interest for a Linux device driver).
> 
> But, I am not sure about the design approaches used to support 
> previous switch modules in u-boot.
> 
> Also I had a query whether there is a common switch framework in-place/under-consideration
> in u-boot, similar to what is already present in OpenWrt code:
> https://dev.openwrt.org/browser/trunk/package/boot/uboot-lantiq/patches/0019-net-switchlib-add-framework-for-ethernet-switch-driv.patch?rev=35292
> 
> Would porting this to u-boot make sense to have a common framework for ethernet switch
> in-place?
> 
> Can you please let me know your views on the same and point me to any 
> reference switch drivers that support these features.

There is some support for switches in U-Boot (e.g. mv88e61xx) but no
framework that I know of; and I suspect what is expected from the
switch in U-Boot is that it does not hamper Ethernet operations,
nothing more. for mv88e61xx, this is done through a fixed configuration.

> Regards,
> Bhupesh

Amicalement,
-- 
Albert.

[U-Boot] Query: Ethernet switch support

[Wolfgang Denk]

Dear Bhupesh,

In message <A1A6EA40F8503D48BB002B42BD65974E0A0C9275@039-SN2MPN1-012.039d.mgd.msft.net> you wrote:
> 
> I am trying to add support of a Vitesse L2 switch in u-boot (in unmanaged configuration).
> I was analyzing whether advanced features like flow control, link-aggregation etc are
> required to be supported for a L2 switch  working in a u-boot bootloader level.
...
> But, I am not sure about the design approaches used to support 
> previous switch modules in u-boot.

Things depend _heavily_ on your specific project requiremnts.  IF all
you need is a working network port then you can probably do with just
the default initialization, determined by the pin strapping (i. e.
your hardware guys should just to The Right Thing (TM) ).

However, if you run a device in a security sensitive environment, it
may be strictly forbidden to run the switch even for very short
periods in some "open" configuration that would - for example - allow
access from the "outside" to some (normally) protected inner networks.


There is at least one board configuration in mainline which performs
a full switch initialization in a time-optimized manner (by just down-
loading a register dump to the switch); see enbw_cmc_config_switch()
in board/enbw/enbw_cmc/enbw_cmc.c


Normally, you should probably leave the switch just turned off /
disabled and wait until proper application code in Linux can perform
the needed initalizations.


Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
CAUTION:  The Mass of This Product Contains the Energy Equivalent  of
85 Million Tons of TNT per Net Ounce of Weight.

[U-Boot] Query: Ethernet switch support

[Sharma Bhupesh-B45370]

Hi Albert,

Thanks for your reply.

> -----Original Message-----
> From: Albert ARIBAUD [mailto:albert.u.boot at aribaud.net]
> Sent: Monday, July 29, 2013 10:27 PM
> To: Sharma Bhupesh-B45370
> Cc: 'u-boot at lists.denx.de'
> Subject: Re: [U-Boot] Query: Ethernet switch support
> 
> Hi Sharma,
> 
> On Mon, 29 Jul 2013 15:33:39 +0000, Sharma Bhupesh-B45370
> <B45370@freescale.com> wrote:
> 
> > Hi List,
> >
> > I am trying to add support of a Vitesse L2 switch in u-boot (in
> unmanaged configuration).
> > I was analyzing whether advanced features like flow control,
> > link-aggregation etc are required to be supported for a L2 switch
> working in a u-boot bootloader level.
> >
> > My point-of-view is that the L2 switch, should support only
> > bare-minimum tftp of images, ping to other ethernet entities, bootp ..
> > type of commands on u-boot and as such the L2 switch u-boot driver
> > doesn't need to address flow-control and other such advanced features
> > (probably of interest for a Linux device driver).
> >
> > But, I am not sure about the design approaches used to support
> > previous switch modules in u-boot.
> >
> > Also I had a query whether there is a common switch framework
> > in-place/under-consideration in u-boot, similar to what is already
> present in OpenWrt code:
> > https://dev.openwrt.org/browser/trunk/package/boot/uboot-lantiq/patche
> > s/0019-net-switchlib-add-framework-for-ethernet-switch-driv.patch?rev=
> > 35292
> >
> > Would porting this to u-boot make sense to have a common framework for
> > ethernet switch in-place?
> >
> > Can you please let me know your views on the same and point me to any
> > reference switch drivers that support these features.
> 
> There is some support for switches in U-Boot (e.g. mv88e61xx) but no
> framework that I know of; and I suspect what is expected from the switch
> in U-Boot is that it does not hamper Ethernet operations, nothing more.
> for mv88e61xx, this is done through a fixed configuration.
> 

In my use-case also the L2 switch is supposed to be configured via a
fixed configuration (setting up the switch in an unmanaged configuration).

I will try to have a look the mv88e61xx example and then formulate something
on similar lines.

Regards,
Bhupesh