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Date:   Fri, 7 Apr 2023 13:50:54 +0300
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Subject: Re: [RFC PATCH net-next] net: dsa: mt7530: fix port specifications
 for MT7988
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From:   =?UTF-8?B?QXLEsW7DpyDDnE5BTA==?= <arinc.unal@arinc9.com>
To:     Daniel Golle <daniel@makrotopia.org>
Cc:     "Russell King (Oracle)" <linux@armlinux.org.uk>,
        Sean Wang <sean.wang@mediatek.com>,
        Landen Chao <Landen.Chao@mediatek.com>,
        DENG Qingfang <dqfext@gmail.com>, Andrew Lunn <andrew@lunn.ch>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Vladimir Oltean <olteanv@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        erkin.bozoglu@xeront.com, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org
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On 7.04.2023 13:46, Arınç ÜNAL wrote:
> 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?

Nevermind, it is necessary. I confused the return logic. This looks good 
to me. Should I take this to my current series? It will conflict with 
sanity check changes as I also remove pad_setup from there.

Arınç