We should disable tx/rx delay in rgmii mode, but driver doesn't do so.
Hence add a device tree property to avoid breaking current users and
disable only when this property is set

<Fixme: change author to ...>
Signed-off-by: Vinod Koul <vk...@kernel.org>
---
 drivers/net/dsa/qca8k.c | 27 ++++++++++++++++++---------
 1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/drivers/net/dsa/qca8k.c b/drivers/net/dsa/qca8k.c
index 7e97e620bd44..6dfb390ebe66 100644
--- a/drivers/net/dsa/qca8k.c
+++ b/drivers/net/dsa/qca8k.c
@@ -420,7 +420,9 @@ qca8k_mib_init(struct qca8k_priv *priv)
 static int
 qca8k_set_pad_ctrl(struct qca8k_priv *priv, int port, int mode)
 {
-       u32 reg;
+       u32 reg, val;
+       struct dsa_switch *ds = priv->ds;
+       bool rx_delay_disable, tx_delay_disable;
 
        switch (port) {
        case 0:
@@ -439,17 +441,24 @@ qca8k_set_pad_ctrl(struct qca8k_priv *priv, int port, int 
mode)
         */
        switch (mode) {
        case PHY_INTERFACE_MODE_RGMII:
-               qca8k_write(priv, reg,
-                           QCA8K_PORT_PAD_RGMII_EN |
-                           QCA8K_PORT_PAD_RGMII_TX_DELAY(3) |
-                           QCA8K_PORT_PAD_RGMII_RX_DELAY(3));
-
-               /* According to the datasheet, RGMII delay is enabled through
+               rx_delay_disable = of_property_read_bool(ds->dst->cpu_dp->dn,
+                                                        "rx-delay-disable");
+               tx_delay_disable = of_property_read_bool(ds->dst->cpu_dp->dn,
+                                                        "tx-delay-disable");
+               val = QCA8K_PORT_PAD_RGMII_EN;
+               if (!rx_delay_disable)
+                       val |= QCA8K_PORT_PAD_RGMII_RX_DELAY(3);
+               if (!tx_delay_disable)
+                       val |= QCA8K_PORT_PAD_RGMII_TX_DELAY(3);
+               qca8k_write(priv, reg, val);
+
+               /* According to the datasheet, RGMII rx delay is enabled through
                 * PORT5_PAD_CTRL for all ports, rather than individual port
                 * registers
                 */
-               qca8k_write(priv, QCA8K_REG_PORT5_PAD_CTRL,
-                           QCA8K_PORT_PAD_RGMII_RX_DELAY_EN);
+               if (!rx_delay_disable)
+                       qca8k_write(priv, QCA8K_REG_PORT5_PAD_CTRL,
+                                   QCA8K_PORT_PAD_RGMII_RX_DELAY_EN);
                break;
        case PHY_INTERFACE_MODE_SGMII:
                qca8k_write(priv, reg, QCA8K_PORT_PAD_SGMII_EN);
-- 
2.20.1

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