Re: [PATCH] net: phy: broadcom: add support for BCM5221 phy

Hello Andrew,

thank you for reviewing,

On 12/08/23 00:16, Andrew Lunn wrote:

On Fri, Aug 11, 2023 at 11:53:22PM +0200, Giulio Benetti wrote:

quoted

This patch adds the BCM5221 PHY support by reusing
brcm_fet_config_intr() and brcm_fet_handle_interrupt() and
implementing config_init()/suspend()/resume().

Sponsored by: Tekvox Inc.

That is a new tag. Maybe you should update
Documentation/process/submitting-patches.rst ?

I've picked this tag from commit:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=73c289bac05919286f8c7e1660fcaf6ec0468363

it's not "Sponsored-by:", do you think it's better using this last form?

I can send a patch along with V2 of this one for that.

quoted

+static int bcm5221_config_init(struct phy_device *phydev)
+{
+	int reg, err, err2, brcmtest;
+
+	/* Reset the PHY to bring it to a known state. */
+	err = phy_write(phydev, MII_BMCR, BMCR_RESET);
+	if (err < 0)
+		return err;
+
+	/* The datasheet indicates the PHY needs up to 1us to complete a reset,
+	 * build some slack here.
+	 */
+	usleep_range(1000, 2000);
+
+	/* The PHY requires 65 MDC clock cycles to complete a write operation
+	 * and turnaround the line properly.
+	 *
+	 * We ignore -EIO here as the MDIO controller (e.g.: mdio-bcm-unimac)
+	 * may flag the lack of turn-around as a read failure. This is
+	 * particularly true with this combination since the MDIO controller
+	 * only used 64 MDC cycles. This is not a critical failure in this
+	 * specific case and it has no functional impact otherwise, so we let
+	 * that one go through. If there is a genuine bus error, the next read
+	 * of MII_BRCM_FET_INTREG will error out.
+	 */
+	err = phy_read(phydev, MII_BMCR);
+	if (err < 0 && err != -EIO)
+		return err;

It is pretty normal to check the value of MII_BMCR and ensure that
BMCR_RESET has cleared. See phy_poll_reset(). It might not be needed,
if you trust the datasheet, but 802.3 C22 says it should clear.

oh ok, I'll do that on V2

quoted

+	/* Enable auto MDIX */
+	err = phy_clear_bits(phydev, BCM5221_AEGSR, BCM5221_AEGSR_MDIX_DIS);
+	if (err < 0)
+		return err;

It is better to set it based on phydev->mdix_ctrl.

ok,

quoted

@@ -1288,6 +1431,7 @@ static struct mdio_device_id __maybe_unused broadcom_tbl[] = {
  	{ PHY_ID_BCM53125, 0xfffffff0 },
  	{ PHY_ID_BCM53128, 0xfffffff0 },
  	{ PHY_ID_BCM89610, 0xfffffff0 },
+	{ PHY_ID_BCM5221, 0xfffffff0 },

This table has some sort of sorting. I would put this new entry before
PHY_ID_BCM5241.

right, this and even the struct phy_driver driver entry too then,

quoted

  #define PHY_ID_BCM50610			0x0143bd60
  #define PHY_ID_BCM50610M		0x0143bd70
  #define PHY_ID_BCM5241			0x0143bc30
+#define PHY_ID_BCM5221			0x004061e0

The value looks odd. Is the OUI correct? Is that a broadcom OUI?

Yes, you can check it in the pdf page 37:
https://docs.broadcom.com/doc/5221-DS07-405-RDS.pdf
and yes, it's odd.

Thanks again for the review, I'll do the changes here and the others
suggested by the other and send V2 patch.

Best regards
-- 
Giulio Benetti
CEO&CTO@Benetti Engineering sas