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

From: Arınç ÜNAL
Date: Fri Apr 07 2023 - 06:53:55 EST


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@xxxxxxxxx wrote:
From: Arınç ÜNAL <arinc.unal@xxxxxxxxxx>

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@xxxxxxxxxx>
---

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