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

Vladimir Oltean
2023-05-24T18:15:49Z

On Mon, May 22, 2023 at 03:15:14PM +0300, arinc9.unal@gmail.com wrote:
> From: Arınç ÜNAL <arinc.unal@arinc9.com>
>
> 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@arinc9.com>
> Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
> ---

Do you know why a crystal frequency of 20 MHz is not supported?

> 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.

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.

> + return -EINVAL;
> + }
> +
> /* Reset the switch through internal reset */
> mt7530_write(priv, MT7530_SYS_CTRL,
> SYS_CTRL_PHY_RST | SYS_CTRL_SW_RST |
> --
> 2.39.2