Re: [PATCH net-next] net: stmmac: stm32: Set TSO/TBS Tx queues default settings

[Jakub Kicinski <kuba@kernel.org>]

On Tue, 18 Aug 2026 08:57:08 +0200 Kurt Kanzenbach wrote:
> On Mon Aug 17 2026, Jakub Kicinski wrote:
> > On Wed, 12 Aug 2026 08:28:57 +0200 Kurt Kanzenbach wrote:  
> >> TSO and TBS cannot coexist. Use the first queue with TSO and the rest for
> >> TBS. Tx queues with TBS can support etf qdisc hw offload. This is done
> >> similar to dwmac-imx and dwmac-intel.  
> >
> > Can you explain your use case?  
> 
> I want to use ETF Qdisc with hardware offload, which is currently not
> possible on the stm32mp2.

Do you need multiple queues for ETF/normal traffic?
Or one ETF and one "normal"?

How do you sort the traffic between the queues?

> > And how many queues the device has in total?  
> 
> The stm32mp2 has four Tx and two Rx queues.
> 
> > You say "TSO and TBS cannot coexist" but can any queue on your
> > platform be configured to support either feature?  
> 
> I think so. The data sheet says: "Do not enable time-based scheduling for
> channels on which the TSO feature is enabled.". But, I didn't find any
> limitations on what queue/channel can enable TBS.

👍️

> > If yes why are we configuring this statically instead of making
> > appropriate configuration based on qdisc or some other uAPI knob?  
> 
> It seems like a static configuration in the driver today. I basically
> followed the same convention as dwmac-imx, dwmac-intel, dwmac-mediatek
> and dwmac-qcom-ethqos. Only dwmac-socfpga does it differently.
> 
> Tx Launch Time requires a different DMA descriptor layout. Currently
> tc_setup_etf() just returns -EINVAL if the DMA configuration is not
> setup appropriately. I guess a dynamic configuration requires to change
> the DMA config and perform a full release/open cycle.

release/open is not ideal but still better than hardcoding?