6.12-stable review patch. If anyone has any objections, please let me know.
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From: Oleksij Rempel o.rempel@pengutronix.de
commit 3ceb6ac2116ecda1c5d779bb73271479e70fccb4 upstream.
Correct RGMII delay application logic in lan937x_set_tune_adj().
The function was missing `data16 &= ~PORT_TUNE_ADJ` before setting the new delay value. This caused the new value to be bitwise-OR'd with the existing PORT_TUNE_ADJ field instead of replacing it.
For example, when setting the RGMII 2 TX delay on port 4, the intended TUNE_ADJUST value of 0 (RGMII_2_TX_DELAY_2NS) was incorrectly OR'd with the default 0x1B (from register value 0xDA3), leaving the delay at the wrong setting.
This patch adds the missing mask to clear the field, ensuring the correct delay value is written. Physical measurements on the RGMII TX lines confirm the fix, showing the delay changing from ~1ns (before change) to ~2ns.
While testing on i.MX 8MP showed this was within the platform's timing tolerance, it did not match the intended hardware-characterized value.
Fixes: b19ac41faa3f ("net: dsa: microchip: apply rgmii tx and rx delay in phylink mac config") Cc: stable@vger.kernel.org Signed-off-by: Oleksij Rempel o.rempel@pengutronix.de Link: https://patch.msgid.link/20251114090951.4057261-1-o.rempel@pengutronix.de Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/dsa/microchip/lan937x_main.c | 1 + 1 file changed, 1 insertion(+)
--- a/drivers/net/dsa/microchip/lan937x_main.c +++ b/drivers/net/dsa/microchip/lan937x_main.c @@ -339,6 +339,7 @@ static void lan937x_set_tune_adj(struct ksz_pread16(dev, port, reg, &data16);
/* Update tune Adjust */ + data16 &= ~PORT_TUNE_ADJ; data16 |= FIELD_PREP(PORT_TUNE_ADJ, val); ksz_pwrite16(dev, port, reg, data16);