Re: [RFC PATCH net-next] net: dsa: mt7530: fix port specifications for MT7988

["Arınç ÜNAL" <arinc.unal@arinc9.com>]

On 7.04.2023 12:28, Daniel Golle wrote:
> On Fri, Apr 07, 2023 at 11:56:08AM +0300, Arınç ÜNAL wrote:
>> On 7.04.2023 00:57, Daniel Golle wrote:
>>> On Fri, Apr 07, 2023 at 12:43:41AM +0300, Arınç ÜNAL wrote:
>>>> On 6.04.2023 14:07, Russell King (Oracle) wrote:
>>>>> On Thu, Apr 06, 2023 at 01:04:45PM +0300, arinc9.unal@gmail.com wrote:
>>>>>> From: Arınç ÜNAL <arinc.unal@arinc9.com>
>>>>>>
>>>>>> On the switch on the MT7988 SoC, there are only 4 PHYs. There's only port 6
>>>>>> as the CPU port, there's no port 5. Split the switch statement with a check
>>>>>> to enforce these for the switch on the MT7988 SoC. The internal phy-mode is
>>>>>> specific to MT7988 so put it for MT7988 only.
>>>>>>
>>>>>> Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
>>>>>> ---
>>>>>>
>>>>>> Daniel, this is based on the information you provided me about the switch.
>>>>>> I will add this to my current patch series if it looks good to you.
>>>>>>
>>>>>> Arınç
>>>>>>
>>>>>> ---
>>>>>>     drivers/net/dsa/mt7530.c | 67 ++++++++++++++++++++++++++--------------
>>>>>>     1 file changed, 43 insertions(+), 24 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
>>>>>> index 6fbbdcb5987f..f167fa135ef1 100644
>>>>>> --- a/drivers/net/dsa/mt7530.c
>>>>>> +++ b/drivers/net/dsa/mt7530.c
>>>>>> @@ -2548,7 +2548,7 @@ static void mt7988_mac_port_get_caps(struct dsa_switch *ds, int port,
>>>>>>     	phy_interface_zero(config->supported_interfaces);
>>>>>>     	switch (port) {
>>>>>> -	case 0 ... 4: /* Internal phy */
>>>>>> +	case 0 ... 3: /* Internal phy */
>>>>>>     		__set_bit(PHY_INTERFACE_MODE_INTERNAL,
>>>>>>     			  config->supported_interfaces);
>>>>>>     		break;
>>>>>> @@ -2710,37 +2710,56 @@ mt753x_phylink_mac_config(struct dsa_switch *ds, int port, unsigned int mode,
>>>>>>     	struct mt7530_priv *priv = ds->priv;
>>>>>>     	u32 mcr_cur, mcr_new;
>>>>>> -	switch (port) {
>>>>>> -	case 0 ... 4: /* Internal phy */
>>>>>> -		if (state->interface != PHY_INTERFACE_MODE_GMII &&
>>>>>> -		    state->interface != PHY_INTERFACE_MODE_INTERNAL)
>>>>>> -			goto unsupported;
>>>>>> -		break;
>>>>>> -	case 5: /* Port 5, a CPU port. */
>>>>>> -		if (priv->p5_interface == state->interface)
>>>>>> +	if (priv->id == ID_MT7988) {
>>>>>> +		switch (port) {
>>>>>> +		case 0 ... 3: /* Internal phy */
>>>>>> +			if (state->interface != PHY_INTERFACE_MODE_INTERNAL)
>>>>>
>>>>> How do these end up with PHY_INTERFACE_MODE_INTERNAL ? phylib defaults
>>>>> to GMII mode without something else being specified in DT.
>>>>>
>>>>> Also note that you should *not* be validating state->interface in the
>>>>> mac_config() method because it's way too late to reject it - if you get
>>>>> an unsupported interface here, then that is down to the get_caps()
>>>>> method being buggy. Only report interfaces in get_caps() that you are
>>>>> prepared to handle in the rest of the system.
>>>>
>>>> This is already the case for all three get_caps(). The supported interfaces
>>>> for each port are properly defined.
>>>>
>>>> Though mt7988_mac_port_get_caps() clears the config->supported_interfaces
>>>> bitmap before reporting the supported interfaces. I don't think this is
>>>> needed as all bits in the bitmap should already be initialized to zero when
>>>> the phylink_config structure is allocated.
>>>>
>>>> I'm not sure if your suggestion is to make sure the supported interfaces are
>>>> properly reported on get_caps(), or validate state->interface somewhere
>>>> else.
>>>
>>> I think what Russell meant is just there is no point in being overly
>>> precise about permitted interface modes in mt753x_phylink_mac_config,
>>> as this function is not meant and called too late to validate the
>>> validity of the selected interface mode.
>>>
>>> You change to mt7988_mac_port_get_caps looks correct to me and doing
>>> this will already prevent mt753x_phylink_mac_config from ever being
>>> called on MT7988 for port == 4 as well as and port == 5.
>>
>> Ah, thanks for pointing this out Daniel. I see ds->ops->phylink_get_caps()
>> is run right before phylink_create() on dsa_port_phylink_create(), as it
>> should get the capabilities before creating an instance.
>>
>> Should I remove phy_interface_zero(config->supported_interfaces);
>> mt7988_mac_port_get_caps()? I'd prefer to do identical operations on each
>> get_caps(), if there's no apparent reason for this to be on
>> mt7988_mac_port_get_caps().
> 
> Yes, sounds sane to me, please do so.
> 
> Also we could make .mac_port_config optional, as for MT7988 we actually
> won't need it at all:
> 
> diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
> index e4bb5037d3525..5efcb9897eb18 100644
> --- a/drivers/net/dsa/mt7530.c
> +++ b/drivers/net/dsa/mt7530.c
> @@ -2653,17 +2653,6 @@ static bool mt753x_is_mac_port(u32 port)
>   	return (port == 5 || port == 6);
>   }
>   
> -static int
> -mt7988_mac_config(struct dsa_switch *ds, int port, unsigned int mode,
> -		  phy_interface_t interface)
> -{
> -	if (dsa_is_cpu_port(ds, port) &&
> -	    interface == PHY_INTERFACE_MODE_INTERNAL)
> -		return 0;
> -
> -	return -EINVAL;
> -}
> -
>   static int
>   mt7531_mac_config(struct dsa_switch *ds, int port, unsigned int mode,
>   		  phy_interface_t interface)
> @@ -2704,6 +2693,9 @@ mt753x_mac_config(struct dsa_switch *ds, int port, unsigned int mode,
>   {
>   	struct mt7530_priv *priv = ds->priv;
>   
> +	if (!priv->info->mac_port_config)
> +		return 0;
> +
>   	return priv->info->mac_port_config(ds, port, mode, state->interface);
>   }
>   
> @@ -3157,7 +3149,6 @@ const struct mt753x_info mt753x_table[] = {
>   		.pad_setup = mt7988_pad_setup,
>   		.cpu_port_config = mt7988_cpu_port_config,
>   		.mac_port_get_caps = mt7988_mac_port_get_caps,
> -		.mac_port_config = mt7988_mac_config,
>   	},
>   };
>   EXPORT_SYMBOL_GPL(mt753x_table);
> @@ -3186,8 +3177,7 @@ mt7530_probe_common(struct mt7530_priv *priv)
>   	 */
>   	if (!priv->info->sw_setup || !priv->info->pad_setup ||
>   	    !priv->info->phy_read_c22 || !priv->info->phy_write_c22 ||
> -	    !priv->info->mac_port_get_caps ||
> -	    !priv->info->mac_port_config)
> +	    !priv->info->mac_port_get_caps)

Why split the sanity check? Isn't just removing mt7988_mac_config() and 
.mac_port_config = mt7988_mac_config enough?

Arınç