Re: [PATCH net-next v3 2/2] net: dsa: mv88e6xxx: add support for credit based shaper

[Cedric Jehasse]

On Thu, May 28, 2026 at 8:28 AM Luke Howard <lukeh@xxxxxxxx> wrote:
>
> Hi Cedric,
>
> One further comment: the Marvell DSDT reference implementation (GPLv2) also sets an undocumented register on the 6352 family of switches to enable CBS. (This does not apply to the 6390 family.)
>
> My understanding is that you should call mv88e6xxx_port_qav_read(MV88E6352_PORT_QAV_CFG) and then set or unset MV88E6352_PORT_QAV_CFG_ENABLE accordingly.
>
> The values are given below:
>
> #define MV88E6352_PORT_QAV_CFG                    0x08
> #define MV88E6352_PORT_QAV_CFG_ENABLE             0x8000
>

I'm wondering if this is needed.
I can't find this in the UMSD, which is newer than the DSDT. Why was this
removed by Marvell? And the register is undocumented.

Cedric