Re: [net-next RFC PATCH v4 15/15] net: dsa: qca8k: cache lo and hi for mdio write

Ansuel Smith
2021-12-12T17:43:44Z

On Sat, Dec 11, 2021 at 08:04:42PM -0800, Florian Fainelli wrote:
>
>
> On 12/11/2021 11:57 AM, Ansuel Smith wrote:
> > From Documentation, we can cache lo and hi the same way we do with the
> > page. This massively reduce the mdio write as 3/4 of the time we only
> > require to write the lo or hi part for a mdio write.
> >
> > Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
> > ---
> > drivers/net/dsa/qca8k.c | 49 ++++++++++++++++++++++++++++++++++++-----
> > 1 file changed, 44 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/net/dsa/qca8k.c b/drivers/net/dsa/qca8k.c
> > index 375a1d34e46f..b109a74031c6 100644
> > --- a/drivers/net/dsa/qca8k.c
> > +++ b/drivers/net/dsa/qca8k.c
> > @@ -94,6 +94,48 @@ qca8k_split_addr(u32 regaddr, u16 *r1, u16 *r2, u16 *page)
> > *page = regaddr & 0x3ff;
> > }
> > +static u16 qca8k_current_lo = 0xffff;
>
> Let's assume I have two qca8k switches in my system on the same or a
> different MDIO bus, is not the caching supposed to be a per-qca8k switch
> instance thing?
>

Also another user made me notice this... This problem is present from
when the driver was implemented and I think with the assumption that
only one switch was present in the device. We actually found SoC with 2
qca8k switch.
I will add a patch to move these stuff (and the cache page variable) in
the qca8k priv.

> > +
> > +static int
> > +qca8k_set_lo(struct mii_bus *bus, int phy_id, u32 regnum, u16 lo)
> > +{
> > + int ret;
> > +
> > + if (lo == qca8k_current_lo) {
> > + // pr_info("SAME LOW");
>
> Stray debugging left.
>

Sorry.

> > + return 0;
> > + }
> > +
> > + ret = bus->write(bus, phy_id, regnum, lo);
> > + if (ret < 0)
> > + dev_err_ratelimited(&bus->dev,
> > + "failed to write qca8k 32bit lo register\n");
> > +
> > + qca8k_current_lo = lo;
> > + return 0;
> > +}
> > +
> > +static u16 qca8k_current_hi = 0xffff;
> > +
> > +static int
> > +qca8k_set_hi(struct mii_bus *bus, int phy_id, u32 regnum, u16 hi)
> > +{
> > + int ret;
> > +
> > + if (hi == qca8k_current_hi) {
> > + // pr_info("SAME HI");
>
> Likewise
> --
> Florian

--
Ansuel