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

Arınç ÜNAL
2023-05-25T07:05:36Z

On 24.05.2023 21:15, Vladimir Oltean wrote:
> 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?

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