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From:   Oleksij Rempel <o.rempel@pengutronix.de>
To:     Shawn Guo <shawnguo@kernel.org>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        Andrew Lunn <andrew@lunn.ch>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Heiner Kallweit <hkallweit1@gmail.com>
Cc:     Oleksij Rempel <o.rempel@pengutronix.de>, kernel@pengutronix.de,
        netdev@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org, linux-imx@nxp.com,
        Fabio Estevam <festevam@gmail.com>,
        David Jander <david@protonic.nl>,
        Russell King <linux@armlinux.org.uk>
Subject: [PATCH v2] ARM: imx: allow to disable board specific PHY fixups
Date:   Sun, 29 Mar 2020 13:04:57 +0200
Message-Id: <20200329110457.4113-1-o.rempel@pengutronix.de>
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Sender: linux-kernel-owner@vger.kernel.org
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All PHY fixups located in imx and mxs machine code are PHY and/or board
specific. Never the less, they are applied to all boards independent on
how related PHY is actually connected. As result:
- we have boards with wrong PHY defaults which are not overwritten or
  not properly handled by PHY drivers.
- Some PHY driver changes was never tested and bugs was never detected
  due the fixups.
- Same PHY specific errata was fixed by SoC specific fixup, so the same
  issues should be investigated again after switching to different SoC
  on same board.

Since removing this fixups will brake may existing boards, we'll provide a
Kconfig option which can be used by kernel developers and system integrators.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
---
 arch/arm/mach-imx/mach-imx6q.c  |  3 ++-
 arch/arm/mach-imx/mach-imx6sx.c |  3 ++-
 arch/arm/mach-imx/mach-imx7d.c  |  3 ++-
 arch/arm/mach-mxs/mach-mxs.c    |  3 ++-
 drivers/net/phy/Kconfig         | 16 ++++++++++++++++
 5 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/arch/arm/mach-imx/mach-imx6q.c b/arch/arm/mach-imx/mach-imx6q.c
index edd26e0ffeec..aabf0d8c23a9 100644
--- a/arch/arm/mach-imx/mach-imx6q.c
+++ b/arch/arm/mach-imx/mach-imx6q.c
@@ -162,7 +162,8 @@ static int ar8035_phy_fixup(struct phy_device *dev)
 
 static void __init imx6q_enet_phy_init(void)
 {
-	if (IS_BUILTIN(CONFIG_PHYLIB)) {
+	if (IS_BUILTIN(CONFIG_PHYLIB) &&
+	    IS_BUILTIN(CONFIG_DEPRECATED_PHY_FIXUPS)) {
 		phy_register_fixup_for_uid(PHY_ID_KSZ9021, MICREL_PHY_ID_MASK,
 				ksz9021rn_phy_fixup);
 		phy_register_fixup_for_uid(PHY_ID_KSZ9031, MICREL_PHY_ID_MASK,
diff --git a/arch/arm/mach-imx/mach-imx6sx.c b/arch/arm/mach-imx/mach-imx6sx.c
index d5310bf307ff..fdd9bef27625 100644
--- a/arch/arm/mach-imx/mach-imx6sx.c
+++ b/arch/arm/mach-imx/mach-imx6sx.c
@@ -35,7 +35,8 @@ static int ar8031_phy_fixup(struct phy_device *dev)
 #define PHY_ID_AR8031   0x004dd074
 static void __init imx6sx_enet_phy_init(void)
 {
-	if (IS_BUILTIN(CONFIG_PHYLIB))
+	if (IS_BUILTIN(CONFIG_PHYLIB) &&
+	    IS_BUILTIN(CONFIG_DEPRECATED_PHY_FIXUPS))
 		phy_register_fixup_for_uid(PHY_ID_AR8031, 0xffffffff,
 					   ar8031_phy_fixup);
 }
diff --git a/arch/arm/mach-imx/mach-imx7d.c b/arch/arm/mach-imx/mach-imx7d.c
index ebb27592a9f7..1d3d67c247a3 100644
--- a/arch/arm/mach-imx/mach-imx7d.c
+++ b/arch/arm/mach-imx/mach-imx7d.c
@@ -49,7 +49,8 @@ static int bcm54220_phy_fixup(struct phy_device *dev)
 
 static void __init imx7d_enet_phy_init(void)
 {
-	if (IS_BUILTIN(CONFIG_PHYLIB)) {
+	if (IS_BUILTIN(CONFIG_PHYLIB) &&
+	    IS_BUILTIN(CONFIG_DEPRECATED_PHY_FIXUPS)) {
 		phy_register_fixup_for_uid(PHY_ID_AR8031, 0xffffffff,
 					   ar8031_phy_fixup);
 		phy_register_fixup_for_uid(PHY_ID_BCM54220, 0xffffffff,
diff --git a/arch/arm/mach-mxs/mach-mxs.c b/arch/arm/mach-mxs/mach-mxs.c
index c109f47e9cbc..b4b631242080 100644
--- a/arch/arm/mach-mxs/mach-mxs.c
+++ b/arch/arm/mach-mxs/mach-mxs.c
@@ -257,7 +257,8 @@ static void __init apx4devkit_init(void)
 {
 	enable_clk_enet_out();
 
-	if (IS_BUILTIN(CONFIG_PHYLIB))
+	if (IS_BUILTIN(CONFIG_PHYLIB) &&
+	    IS_BUILTIN(CONFIG_DEPRECATED_PHY_FIXUPS))
 		phy_register_fixup_for_uid(PHY_ID_KSZ8051, MICREL_PHY_ID_MASK,
 					   apx4devkit_phy_fixup);
 }
diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig
index 9dabe03a668c..f54428ddf058 100644
--- a/drivers/net/phy/Kconfig
+++ b/drivers/net/phy/Kconfig
@@ -249,6 +249,22 @@ config LED_TRIGGER_PHY
 		<Speed in megabits>Mbps OR <Speed in gigabits>Gbps OR link
 		for any speed known to the PHY.
 
+config DEPRECATED_PHY_FIXUPS
+	bool "Enable deprecated PHY fixups"
+	default y
+	---help---
+	  In the early days it was common practice to configure PHYs by adding a
+	  phy_register_fixup*() in the machine code. This practice turned out to
+	  be potentially dangerous, because:
+	  - it affects all PHYs in the system
+	  - these register changes are usually not preserved during PHY reset
+	    or suspend/resume cycle.
+	  - it complicates debugging, since these configuration changes were not
+	    done by the actual PHY driver.
+	  This option allows to disable all fixups which are identified as
+	  potentially harmful and give the developers a chance to implement the
+	  proper configuration via the device tree (e.g.: phy-mode) and/or the
+	  related PHY drivers.
 
 comment "MII PHY device drivers"
 
-- 
2.26.0.rc2