Re: [PATCH net v3 1/3] net: stmmac: Limit the number of MTL queues to hardware capability

[Kunihiko Hayashi]

On 2025/01/24 20:43, Russell King (Oracle) wrote:
> On Fri, Jan 24, 2025 at 07:13:57PM +0900, Kunihiko Hayashi wrote:
> > The number of MTL queues to use is specified by the parameter
> > "snps,{tx,rx}-queues-to-use" from stmmac_platform layer.
> >
> > However, the maximum numbers of queues are constrained by upper limits
> > determined by the capability of each hardware feature. It's appropriate
> > to limit the values not to exceed the upper limit values and display
> > a warning message.
> >
> > This only works if the hardware capability has the upper limit values.
> >
> > Fixes: d976a525c371 ("net: stmmac: multiple queues dt configuration")
> > Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@xxxxxxxxxxxxx>
> > ---
> >   drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 15 +++++++++++++++
> >   1 file changed, 15 insertions(+)
> >
> > diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> > index 7bf275f127c9..be1e6fa6d557 100644
> > --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> > +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> > @@ -7232,6 +7232,21 @@ static int stmmac_hw_init(struct stmmac_priv
> *priv)
> >   	if (priv->dma_cap.tsoen)
> >   		dev_info(priv->device, "TSO supported\n");
> >   
> > +	if (priv->dma_cap.number_rx_queues &&
> > +	    priv->dma_cap.number_rx_queues < priv->plat->rx_queues_to_use)
> {
>
> While this looks "nicer", which of these two do you think reads better
> and is easier to understand:
>
> "If priv->dma_cap.number_rx_queues is set, and
>   priv->dma_cap.number_rx_queues is less than
>   priv->plat->rx_queues_to_use then print a message about
>   priv->plat->rx_queues_to_use exceeding priv->dma_cap.number_rx_queues"
>
> "If priv->dma_cap.number_rx_queues is set, and
>   priv->plat->rx_queues_to_use is greater than
>   priv->dma_cap.number_rx_queues, then print a message about
>   priv->plat->rx_queues_to_use exceeding priv->dma_cap.number_rx_queues"
>
> With the former one has to mentally flip the test around in the if
> statement to check that it does indeed match the warning that is
> printed.

This patch focuses only on the conditional lines, however, certainly
it's not good to have the meaning of the message and the condition
reversed.

I'll fix it next.

Thank you,

---
Best Regards
Kunihiko Hayashi