Re: [PATCH net-next v3 2/9] net: dsa: microchip: ksz8795: add phylink support

On Thu, May 27, 2021 at 01:13:04AM +0300, Vladimir Oltean wrote:

On Wed, May 26, 2021 at 06:30:30AM +0200, Oleksij Rempel wrote:

quoted

From: Michael Grzeschik <redacted>

This patch adds the phylink support to the ksz8795 driver to provide
configuration exceptions on quirky KSZ8863 and KSZ8873 ports.

Signed-off-by: Michael Grzeschik <redacted>
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
---
 drivers/net/dsa/microchip/ksz8795.c | 59 +++++++++++++++++++++++++++++
 1 file changed, 59 insertions(+)

diff --git a/drivers/net/dsa/microchip/ksz8795.c b/drivers/net/dsa/microchip/ksz8795.c
index ba065003623f..cf81ae87544d 100644
--- a/drivers/net/dsa/microchip/ksz8795.c
+++ b/drivers/net/dsa/microchip/ksz8795.c

@@ -18,6 +18,7 @@
 #include <linux/micrel_phy.h>
 #include <net/dsa.h>
 #include <net/switchdev.h>
+#include <linux/phylink.h>
 
 #include "ksz_common.h"
 #include "ksz8795_reg.h"

@@ -1420,11 +1421,69 @@ static int ksz8_setup(struct dsa_switch *ds)
 	return 0;
 }
 
+static void ksz8_validate(struct dsa_switch *ds, int port,
+			  unsigned long *supported,
+			  struct phylink_link_state *state)
+{
+	__ETHTOOL_DECLARE_LINK_MODE_MASK(mask) = { 0, };
+	struct ksz_device *dev = ds->priv;
+
+	if (port == dev->cpu_port) {
+		if (state->interface != PHY_INTERFACE_MODE_RMII &&
+		    state->interface != PHY_INTERFACE_MODE_MII &&
+		    state->interface != PHY_INTERFACE_MODE_NA)
+			goto unsupported;
+	} else if (port > dev->port_cnt) {
+		bitmap_zero(supported, __ETHTOOL_LINK_MODE_MASK_NBITS);
+		dev_err(ds->dev, "Unsupported port: %i\n", port);
+		return;

Is this possible or do we just like to invent things to check?
Unless I'm missing something, ksz8_switch_init() does:

	dev->ds->num_ports = dev->port_cnt;

and dsa_port_phylink_validate() does:

	ds->ops->phylink_validate(ds, dp->index, supported, state);

where dp->index is set to @port by dsa_port_touch() in this loop:

	for (port = 0; port < ds->num_ports; port++) {
		dp = dsa_port_touch(ds, port);
		if (!dp)
			return -ENOMEM;
	}

So, if 0 <= dp->index < ds->num_ports == dev->port_cnt, what is the point?

good point

Regards,
Oleksij
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