[PATCH v2 net] net: mdio-mux-meson-g12a: force internal PHY off on mux switch

From: Jerome Brunet
Date: Tue Jan 24 2023 - 05:13:55 EST


Force the internal PHY off then on when switching to the internal path.
This fixes problems where the PHY ID is not properly set.

Fixes: 7090425104db ("net: phy: add amlogic g12a mdio mux support")
Suggested-by: Qi Duan <qi.duan@xxxxxxxxxxx>
Co-developed-by: Heiner Kallweit <hkallweit1@xxxxxxxxx>
Signed-off-by: Heiner Kallweit <hkallweit1@xxxxxxxxx>
Signed-off-by: Jerome Brunet <jbrunet@xxxxxxxxxxxx>
---

Changes since v1:
- Fix variable position for reverse Xmas tree requirement.

The initial discussion about this change can be found here:
https://lore.kernel.org/all/1j4jslwen5.fsf@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx/

drivers/net/mdio/mdio-mux-meson-g12a.c | 23 ++++++++++++++++-------
1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/drivers/net/mdio/mdio-mux-meson-g12a.c b/drivers/net/mdio/mdio-mux-meson-g12a.c
index 4a2e94faf57e..c4542ecf5623 100644
--- a/drivers/net/mdio/mdio-mux-meson-g12a.c
+++ b/drivers/net/mdio/mdio-mux-meson-g12a.c
@@ -4,6 +4,7 @@
*/

#include <linux/bitfield.h>
+#include <linux/delay.h>
#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/device.h>
@@ -150,6 +151,7 @@ static const struct clk_ops g12a_ephy_pll_ops = {

static int g12a_enable_internal_mdio(struct g12a_mdio_mux *priv)
{
+ u32 value;
int ret;

/* Enable the phy clock */
@@ -163,18 +165,25 @@ static int g12a_enable_internal_mdio(struct g12a_mdio_mux *priv)

/* Initialize ephy control */
writel(EPHY_G12A_ID, priv->regs + ETH_PHY_CNTL0);
- writel(FIELD_PREP(PHY_CNTL1_ST_MODE, 3) |
- FIELD_PREP(PHY_CNTL1_ST_PHYADD, EPHY_DFLT_ADD) |
- FIELD_PREP(PHY_CNTL1_MII_MODE, EPHY_MODE_RMII) |
- PHY_CNTL1_CLK_EN |
- PHY_CNTL1_CLKFREQ |
- PHY_CNTL1_PHY_ENB,
- priv->regs + ETH_PHY_CNTL1);
+
+ /* Make sure we get a 0 -> 1 transition on the enable bit */
+ value = FIELD_PREP(PHY_CNTL1_ST_MODE, 3) |
+ FIELD_PREP(PHY_CNTL1_ST_PHYADD, EPHY_DFLT_ADD) |
+ FIELD_PREP(PHY_CNTL1_MII_MODE, EPHY_MODE_RMII) |
+ PHY_CNTL1_CLK_EN |
+ PHY_CNTL1_CLKFREQ;
+ writel(value, priv->regs + ETH_PHY_CNTL1);
writel(PHY_CNTL2_USE_INTERNAL |
PHY_CNTL2_SMI_SRC_MAC |
PHY_CNTL2_RX_CLK_EPHY,
priv->regs + ETH_PHY_CNTL2);

+ value |= PHY_CNTL1_PHY_ENB;
+ writel(value, priv->regs + ETH_PHY_CNTL1);
+
+ /* The phy needs a bit of time to power up */
+ mdelay(10);
+
return 0;
}

--
2.39.0