Re: [PATCH net-next 12/30] net: dsa: mt7530: move XTAL check to mt7530_setup()

[Arınç ÜNAL]

On 24.05.2023 21:15, Vladimir Oltean wrote:
> On Mon, May 22, 2023 at 03:15:14PM +0300, arinc9.unal@xxxxxxxxx wrote:
> > From: Arınç ÜNAL <arinc.unal@xxxxxxxxxx>
> >
> > The crystal frequency concerns the switch core. The frequency should be
> > checked when the switch is being set up so the driver can reject the
> > unsupported hardware earlier and without requiring port 6 to be used.
> >
> > Move it to mt7530_setup().
> >
> > Tested-by: Arınç ÜNAL <arinc.unal@xxxxxxxxxx>
> > Signed-off-by: Arınç ÜNAL <arinc.unal@xxxxxxxxxx>
> > ---
>
> Do you know why a crystal frequency of 20 MHz is not supported?

I don't know, it just isn't.

https://github.com/BPI-SINOVOIP/BPI-R2-bsp/blob/master/linux-mt/drivers/net/ethernet/mediatek/gsw_mt7623.c#L1076

> >   drivers/net/dsa/mt7530.c | 18 ++++++++++--------
> >   1 file changed, 10 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
> > index 049f7be0d790..fa48273269c4 100644
> > --- a/drivers/net/dsa/mt7530.c
> > +++ b/drivers/net/dsa/mt7530.c
> > @@ -408,13 +408,6 @@ mt7530_setup_port6(struct dsa_switch *ds, phy_interface_t interface)
> >   
> >   	xtal = mt7530_read(priv, MT7530_HWTRAP) & HWTRAP_XTAL_MASK;
> >   
> > -	if (xtal == HWTRAP_XTAL_20MHZ) {
> > -		dev_err(priv->dev,
> > -			"%s: MT7530 with a 20MHz XTAL is not supported!\n",
> > -			__func__);
> > -		return -EINVAL;
> > -	}
> > -
> >   	switch (interface) {
> >   	case PHY_INTERFACE_MODE_RGMII:
> >   		trgint = 0;
> > @@ -2133,7 +2126,7 @@ mt7530_setup(struct dsa_switch *ds)
> >   	struct mt7530_dummy_poll p;
> >   	phy_interface_t interface;
> >   	struct dsa_port *cpu_dp;
> > -	u32 id, val;
> > +	u32 id, val, xtal;
> >   	int ret, i;
> >   
> >   	/* The parent node of master netdev which holds the common system
> > @@ -2203,6 +2196,15 @@ mt7530_setup(struct dsa_switch *ds)
> >   		return -ENODEV;
> >   	}
> >   
> > +	xtal = mt7530_read(priv, MT7530_HWTRAP) & HWTRAP_XTAL_MASK;
> > +
> > +	if (xtal == HWTRAP_XTAL_20MHZ) {
> > +		dev_err(priv->dev,
> > +			"%s: MT7530 with a 20MHz XTAL is not supported!\n",
> > +			__func__);
>
> I don't think __func__ brings much value here, it could be dropped in
> the process of moving the code.

Will do.

> Also, the HWTRAP register is already read once, here (stored in "val"):
>
> 	INIT_MT7530_DUMMY_POLL(&p, priv, MT7530_HWTRAP);
> 	ret = readx_poll_timeout(_mt7530_read, &p, val, val != 0,
> 				 20, 1000000);
>
> I wonder if we really need to read it twice.

Likely not, good catch.

Arınç