RE: [PATCH net-next] net: phy: microchip_t1: add cable test support for lan87xx phy

-----Original Message-----
From: Andrew Lunn <andrew@lunn.ch>
Sent: Wednesday, October 27, 2021 10:47 AM
To: Yuiko Oshino - C18177 <redacted>
Cc: davem@davemloft.net; netdev@vger.kernel.org; Nisar Sayed - I17970
[off-list ref]; UNGLinuxDriver
[off-list ref]
Subject: Re: [PATCH net-next] net: phy: microchip_t1: add cable test support for
lan87xx phy

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quoted

quoted

quoted

+     /* start cable diag */
+     /* check if part is alive - if not, return diagnostic error */
+     rc = access_ereg(phydev, PHYACC_ATTR_MODE_READ,

PHYACC_ATTR_BANK_SMI,

quoted

+                      0x00, 0);
+     if (rc < 0)
+             return rc;
+
+     if (rc != 0x2100)
+             return -ENODEV;

What does this actually mean? Would -EOPNOTSUPP be better?

This register should return the value of 0x2100. So if the return value is different,

then I assume there is no device.

If the device does not exist, can we have go this far? Would probe of the PHY
failed? Or are you talking about a device within a device? Is cable test
implemented using an optional component?

     Andrew

You are right.
I will remove the two lines.
Thank you.
Yuiko