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net: phy: mscc: fix deadlock in vsc85xx_default_config

PATCH Applied Quentin Schulz 3 participants 3 messages Nov 23, 2018 – Nov 24, 2018

Subsystems (3)
Networking Network drivers Ethernet PHY
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Quentin Schulz

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#0 lore raw

PATCH v3 1/1 net: phy: mscc: fix deadlock in vsc85xx_default_config

The vsc85xx_default_config function called in the vsc85xx_config_init function which is used by VSC8530, VSC8531, VSC8540 and VSC8541 PHYs mistakenly calls phy_read and phy_write in-between phy_select_page and phy_restore_page.

phy_select_page and phy_restore_page actually take and release the MDIO bus lock and phy_write and phy_read take and release the lock to write or read to a PHY register.

Let's fix this deadlock by using phy_modify_paged which handles correctly a read followed by a write in a non-standard page.

Fixes 6a0bfbbe20b0 ("net: phy: mscc: migrate to phy_select/restore_page functions")
Signed-off-by Quentin Schulz <[email protected]>

---

v3:
- remove useless goto label and condition,

v2:
- use phy_modify_paged instead of
phy_select_page -> __phy_read -> __phy_write -> phy_restore_page

 drivers/net/phy/mscc.c | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)
drivers/net/phy/mscc.c +5 -9
index 62269e578718..cfe680f78a3f 100644
@@ -810,17 +810,13 @@ static int vsc85xx_default_config(struct phy_device *phydev)
 
 	phydev->mdix_ctrl = ETH_TP_MDI_AUTO;
 	mutex_lock(&phydev->lock);
-	rc = phy_select_page(phydev, MSCC_PHY_PAGE_EXTENDED_2);
-	if (rc < 0)
-		goto out_unlock;
 
-	reg_val = phy_read(phydev, MSCC_PHY_RGMII_CNTL);
-	reg_val &= ~(RGMII_RX_CLK_DELAY_MASK);
-	reg_val |= (RGMII_RX_CLK_DELAY_1_1_NS << RGMII_RX_CLK_DELAY_POS);
-	phy_write(phydev, MSCC_PHY_RGMII_CNTL, reg_val);
+	reg_val = RGMII_RX_CLK_DELAY_1_1_NS << RGMII_RX_CLK_DELAY_POS;
+
+	rc = phy_modify_paged(phydev, MSCC_PHY_PAGE_EXTENDED_2,
+			      MSCC_PHY_RGMII_CNTL, RGMII_RX_CLK_DELAY_MASK,
+			      reg_val);
 
-out_unlock:
-	rc = phy_restore_page(phydev, rc, rc > 0 ? 0 : rc);
 	mutex_unlock(&phydev->lock);
 
 	return rc;
Signature · 1 line
2.17.1
maintainer Reviewed-by on v3 1/1
#1 lore raw
Quoted 9 lines · Quentin Schulz

The vsc85xx_default_config function called in the vsc85xx_config_init function which is used by VSC8530, VSC8531, VSC8540 and VSC8541 PHYs mistakenly calls phy_read and phy_write in-between phy_select_page and phy_restore_page.

phy_select_page and phy_restore_page actually take and release the MDIO bus lock and phy_write and phy_read take and release the lock to write or read to a PHY register.

Quoted 6 lines

Let's fix this deadlock by using phy_modify_paged which handles correctly a read followed by a write in a non-standard page.

Fixes 6a0bfbbe20b0 ("net: phy: mscc: migrate to phy_select/restore_page functions")
Signed-off-by Quentin Schulz <[email protected]>
Reviewed-by Andrew Lunn <[email protected]>

Andrew

maintainer Applied
#2 lore raw
In reply to Quentin Schulz

From: Quentin Schulz <[email protected]>
Date: Fri, 23 Nov 2018 19:01:51 +0100

Quoted 9 lines

The vsc85xx_default_config function called in the vsc85xx_config_init function which is used by VSC8530, VSC8531, VSC8540 and VSC8541 PHYs mistakenly calls phy_read and phy_write in-between phy_select_page and phy_restore_page.

phy_select_page and phy_restore_page actually take and release the MDIO bus lock and phy_write and phy_read take and release the lock to write or read to a PHY register.

Quoted 5 lines

Let's fix this deadlock by using phy_modify_paged which handles correctly a read followed by a write in a non-standard page.

Fixes 6a0bfbbe20b0 ("net: phy: mscc: migrate to phy_select/restore_page functions")
Signed-off-by Quentin Schulz <[email protected]>

Applied.