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

[Daniel Golle <daniel@makrotopia.org>]

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)
 		return -EINVAL;
 
 	priv->id = priv->info->id;

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