Re: [net v4 PATCH] net: stmmac: replace priv->speed with the portTransmitRate from the tc-cbs parameters

[xiaolei wang]

On 6/8/24 19:16, Vladimir Oltean wrote:
> CAUTION: This email comes from a non Wind River email account!
> Do not click links or open attachments unless you recognize the sender and know the content is safe.
>
> On Sat, Jun 08, 2024 at 12:45:57PM +0800, Xiaolei Wang wrote:
> > The current cbs parameter depends on speed after uplinking,
> > which is not needed and will report a configuration error
> > if the port is not initially connected. The UAPI exposed by
> > tc-cbs requires userspace to recalculate the send slope anyway,
> > because the formula depends on port_transmit_rate (see man tc-cbs),
> > which is not an invariant from tc's perspective. Therefore, we
> > use offload->sendslope and offload->idleslope to derive the
> > original port_transmit_rate from the CBS formula.
> >
> > Fixes: 1f705bc61aee ("net: stmmac: Add support for CBS QDISC")
> > Signed-off-by: Xiaolei Wang <xiaolei.wang@xxxxxxxxxxxxx>
> > Reviewed-by: Wojciech Drewek <wojciech.drewek@xxxxxxxxx>
> > ---
> >
> > Change log:
> >
> > v1:
> >      https://patchwork.kernel.org/project/linux-arm-kernel/patch/20240528092010.439089-1-xiaolei.wang@xxxxxxxxxxxxx/
> > v2:
> >      Update CBS parameters when speed changes after linking up
> >      https://patchwork.kernel.org/project/linux-arm-kernel/patch/20240530061453.561708-1-xiaolei.wang@xxxxxxxxxxxxx/
> > v3:
> >      replace priv->speed with the  portTransmitRate from the tc-cbs parameters suggested by Vladimir Oltean
> >      link: https://patchwork.kernel.org/project/linux-arm-kernel/patch/20240607103327.438455-1-xiaolei.wang@xxxxxxxxxxxxx/
> > v4:
> >      Delete speed_div variable, delete redundant port_transmit_rate_kbps = qopt->idleslope - qopt->sendslope; and update commit log
> >
> >   .../net/ethernet/stmicro/stmmac/stmmac_tc.c   | 20 +++++++------------
> >   1 file changed, 7 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c
> > index 222540b55480..87af129a6a1d 100644
> > --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c
> > +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c
> > @@ -344,10 +344,11 @@ static int tc_setup_cbs(struct stmmac_priv *priv,
> >   {
> >        u32 tx_queues_count = priv->plat->tx_queues_to_use;
> >        u32 queue = qopt->queue;
> > -     u32 ptr, speed_div;
> > +     u32 ptr;
> >        u32 mode_to_use;
> >        u64 value;
> >        int ret;
> > +     s64 port_transmit_rate_kbps;
> The feedback that came along with Wojciech's review in v3 was to use
> reverse Christmas tree (RCT) variable ordering. That means to sort
> variable declarations from longest line to shortest. It is the de facto
> coding style standard for kernel networking code.

I will send a new version

thanks

xiaolei

> pw-bot: changes-requested