Re: [net-next PATCH v3 01/14] net: dsa: qca8k: cache match data to speed up access

Christian Marangi
2022-07-24T22:58:39Z

On Mon, Jul 25, 2022 at 01:30:31AM +0300, Vladimir Oltean wrote:
> On Sat, Jul 23, 2022 at 04:18:32PM +0200, Christian Marangi wrote:
> > Using of_device_get_match_data is expensive. Cache match data to speed
>
> 'is expensive' sounds like it's terribly expensive. It's just more than
> it needs to be.
>

Ok will reword.

> > up access and rework user of match data to use the new cached value.
> >
> > Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
> > ---
> > drivers/net/dsa/qca/qca8k.c | 28 ++++++++++------------------
> > drivers/net/dsa/qca/qca8k.h | 1 +
> > 2 files changed, 11 insertions(+), 18 deletions(-)
> >
> > diff --git a/drivers/net/dsa/qca/qca8k.c b/drivers/net/dsa/qca/qca8k.c
> > index 1cbb05b0323f..212b284f9f73 100644
> > --- a/drivers/net/dsa/qca/qca8k.c
> > +++ b/drivers/net/dsa/qca/qca8k.c
> > @@ -3168,6 +3155,11 @@ qca8k_sw_probe(struct mdio_device *mdiodev)
> > if (ret)
> > return ret;
> >
> > + /* Cache match data in priv struct.
> > + * Match data is already checked in read_switch_id.
> > + */
> > + priv->info = of_device_get_match_data(priv->dev);
> > +
>
> So why don't you set priv->info right before calling qca8k_read_switch_id(),
> then?
>

The idea was to make the read_switch_id a function to check if the
switch is compatible... But yhea now that i think about it doesn't
really make sense.

(Just for reference I just sent v4 as I got a report from kernel test
bot... it's really just this series with a change in 0002 patch that set
the struct for ops as a pointer... didn't encounter this with gcc but it
seems kernel test bot use some special config...)

> > priv->ds = devm_kzalloc(&mdiodev->dev, sizeof(*priv->ds), GFP_KERNEL);
> > if (!priv->ds)
> > return -ENOMEM;
> > diff --git a/drivers/net/dsa/qca/qca8k.h b/drivers/net/dsa/qca/qca8k.h
> > index ec58d0e80a70..0b990b46890a 100644
> > --- a/drivers/net/dsa/qca/qca8k.h
> > +++ b/drivers/net/dsa/qca/qca8k.h
> > @@ -401,6 +401,7 @@ struct qca8k_priv {
> > struct qca8k_mdio_cache mdio_cache;
> > struct qca8k_pcs pcs_port_0;
> > struct qca8k_pcs pcs_port_6;
> > + const struct qca8k_match_data *info;
> > };
> >
> > struct qca8k_mib_desc {
> > --
> > 2.36.1
> >
>

--
Ansuel