[PATCH net-next] net: bgmac: support MDIO described in DT

Subsystems: broadcom iproc gbit ethernet driver, networking drivers, the rest

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6 messages, 2 authors, 2021-10-02 · open the first message on its own page

[PATCH net-next] net: bgmac: support MDIO described in DT

From: Rafał Miłecki <zajec5@gmail.com>
Date: 2021-09-20 12:34:54

From: Rafał Miłecki <rafal@milecki.pl>

Check ethernet controller DT node for "mdio" subnode and use it with
of_mdiobus_register() when present. That allows specifying MDIO and its
PHY devices in a standard DT based way.

This is required for BCM53573 SoC support which has an MDIO attached
switch.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
---
 drivers/net/ethernet/broadcom/bgmac-bcma-mdio.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/broadcom/bgmac-bcma-mdio.c b/drivers/net/ethernet/broadcom/bgmac-bcma-mdio.c
index 6ce80cbcb48e..086739e4f40a 100644
--- a/drivers/net/ethernet/broadcom/bgmac-bcma-mdio.c
+++ b/drivers/net/ethernet/broadcom/bgmac-bcma-mdio.c
@@ -10,6 +10,7 @@
 
 #include <linux/bcma/bcma.h>
 #include <linux/brcmphy.h>
+#include <linux/of_mdio.h>
 #include "bgmac.h"
 
 static bool bcma_mdio_wait_value(struct bcma_device *core, u16 reg, u32 mask,
@@ -211,6 +212,7 @@ struct mii_bus *bcma_mdio_mii_register(struct bgmac *bgmac)
 {
 	struct bcma_device *core = bgmac->bcma.core;
 	struct mii_bus *mii_bus;
+	struct device_node *np;
 	int err;
 
 	mii_bus = mdiobus_alloc();
@@ -229,7 +231,9 @@ struct mii_bus *bcma_mdio_mii_register(struct bgmac *bgmac)
 	mii_bus->parent = &core->dev;
 	mii_bus->phy_mask = ~(1 << bgmac->phyaddr);
 
-	err = mdiobus_register(mii_bus);
+	np = of_get_child_by_name(core->dev.of_node, "mdio");
+
+	err = of_mdiobus_register(mii_bus, np);
 	if (err) {
 		dev_err(&core->dev, "Registration of mii bus failed\n");
 		goto err_free_bus;
-- 
2.26.2

Re: [PATCH net-next] net: bgmac: support MDIO described in DT

From: Florian Fainelli <f.fainelli@gmail.com>
Date: 2021-09-20 16:11:12

On 9/20/21 5:34 AM, Rafał Miłecki wrote:
quoted hunk
From: Rafał Miłecki <rafal@milecki.pl>

Check ethernet controller DT node for "mdio" subnode and use it with
of_mdiobus_register() when present. That allows specifying MDIO and its
PHY devices in a standard DT based way.

This is required for BCM53573 SoC support which has an MDIO attached
switch.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
---
 drivers/net/ethernet/broadcom/bgmac-bcma-mdio.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/broadcom/bgmac-bcma-mdio.c b/drivers/net/ethernet/broadcom/bgmac-bcma-mdio.c
index 6ce80cbcb48e..086739e4f40a 100644
--- a/drivers/net/ethernet/broadcom/bgmac-bcma-mdio.c
+++ b/drivers/net/ethernet/broadcom/bgmac-bcma-mdio.c
@@ -10,6 +10,7 @@
 
 #include <linux/bcma/bcma.h>
 #include <linux/brcmphy.h>
+#include <linux/of_mdio.h>
 #include "bgmac.h"
 
 static bool bcma_mdio_wait_value(struct bcma_device *core, u16 reg, u32 mask,
@@ -211,6 +212,7 @@ struct mii_bus *bcma_mdio_mii_register(struct bgmac *bgmac)
 {
 	struct bcma_device *core = bgmac->bcma.core;
 	struct mii_bus *mii_bus;
+	struct device_node *np;
 	int err;
 
 	mii_bus = mdiobus_alloc();
@@ -229,7 +231,9 @@ struct mii_bus *bcma_mdio_mii_register(struct bgmac *bgmac)
 	mii_bus->parent = &core->dev;
 	mii_bus->phy_mask = ~(1 << bgmac->phyaddr);
 
-	err = mdiobus_register(mii_bus);
+	np = of_get_child_by_name(core->dev.of_node, "mdio");
I believe this leaks np and the use case is not exactly clear to me
here. AFAICT the Northstar SoCs have two MDIO controllers: one for
internal PHYs and one for external PHYs which how you would attach a
switch to the chip (in chipcommonA). Is 53573 somewhat different here?
What is the MDIO bus driver that is being used?
-- 
Florian

Re: [PATCH net-next] net: bgmac: support MDIO described in DT

From: Rafał Miłecki <zajec5@gmail.com>
Date: 2021-09-21 00:49:30

On 20.09.2021 18:11, Florian Fainelli wrote:
On 9/20/21 5:34 AM, Rafał Miłecki wrote:
quoted
From: Rafał Miłecki <rafal@milecki.pl>

Check ethernet controller DT node for "mdio" subnode and use it with
of_mdiobus_register() when present. That allows specifying MDIO and its
PHY devices in a standard DT based way.

This is required for BCM53573 SoC support which has an MDIO attached
switch.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
---
  drivers/net/ethernet/broadcom/bgmac-bcma-mdio.c | 6 +++++-
  1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/broadcom/bgmac-bcma-mdio.c b/drivers/net/ethernet/broadcom/bgmac-bcma-mdio.c
index 6ce80cbcb48e..086739e4f40a 100644
--- a/drivers/net/ethernet/broadcom/bgmac-bcma-mdio.c
+++ b/drivers/net/ethernet/broadcom/bgmac-bcma-mdio.c
@@ -10,6 +10,7 @@
  
  #include <linux/bcma/bcma.h>
  #include <linux/brcmphy.h>
+#include <linux/of_mdio.h>
  #include "bgmac.h"
  
  static bool bcma_mdio_wait_value(struct bcma_device *core, u16 reg, u32 mask,
@@ -211,6 +212,7 @@ struct mii_bus *bcma_mdio_mii_register(struct bgmac *bgmac)
  {
  	struct bcma_device *core = bgmac->bcma.core;
  	struct mii_bus *mii_bus;
+	struct device_node *np;
  	int err;
  
  	mii_bus = mdiobus_alloc();
@@ -229,7 +231,9 @@ struct mii_bus *bcma_mdio_mii_register(struct bgmac *bgmac)
  	mii_bus->parent = &core->dev;
  	mii_bus->phy_mask = ~(1 << bgmac->phyaddr);
  
-	err = mdiobus_register(mii_bus);
+	np = of_get_child_by_name(core->dev.of_node, "mdio");
I believe this leaks np and the use case is not exactly clear to me
here. AFAICT the Northstar SoCs have two MDIO controllers: one for
internal PHYs and one for external PHYs which how you would attach a
switch to the chip (in chipcommonA). Is 53573 somewhat different here?
What is the MDIO bus driver that is being used?
of_get_child_by_name() doesn't seem to increase refcount or anything and
I think it's how most drivers handle it. I don't think it should leak.

BCM53573 is a built with some older blocks. Please check:

4ebd50472899 ("ARM: BCM53573: Initial support for Broadcom BCM53573 SoCs")
     BCM53573 series is a new family with embedded wireless. By marketing
     people it's sometimes called Northstar but it uses different CPU and has
     different architecture so we need a new symbol for it.
     Fortunately it shares some peripherals with other iProc based SoCs so we
     will be able to reuse some drivers/bindings.

e90d2d51c412 ("ARM: BCM5301X: Add basic dts for BCM53573 based Tenda AC9")
     BCM53573 seems to be low priced alternative for Northstar chipsts. It
     uses single core Cortex-A7 and doesn't have SDU or local (TWD) timer. It
     was also stripped out of independent SPI controller and 2 GMACs.

Northstar uses SRAB which is some memory based (0x18007000) access to
switch register space.
BCM53573 uses different blocks & mappings and it doesn't include SRAB at
0x18007000. Accessing switch registers is handled over MDIO.

Re: [PATCH net-next] net: bgmac: support MDIO described in DT

From: Rafał Miłecki <zajec5@gmail.com>
Date: 2021-09-30 14:29:35

On 20.09.2021 19:57, Rafał Miłecki wrote:
On 20.09.2021 18:11, Florian Fainelli wrote:
quoted
I believe this leaks np and the use case is not exactly clear to me
here. AFAICT the Northstar SoCs have two MDIO controllers: one for
internal PHYs and one for external PHYs which how you would attach a
switch to the chip (in chipcommonA). Is 53573 somewhat different here?
What is the MDIO bus driver that is being used?
of_get_child_by_name() doesn't seem to increase refcount or anything and
I think it's how most drivers handle it. I don't think it should leak.

BCM53573 is a built with some older blocks. Please check:

4ebd50472899 ("ARM: BCM53573: Initial support for Broadcom BCM53573 SoCs")
     BCM53573 series is a new family with embedded wireless. By marketing
     people it's sometimes called Northstar but it uses different CPU and has
     different architecture so we need a new symbol for it.
     Fortunately it shares some peripherals with other iProc based SoCs so we
     will be able to reuse some drivers/bindings.

e90d2d51c412 ("ARM: BCM5301X: Add basic dts for BCM53573 based Tenda AC9")
     BCM53573 seems to be low priced alternative for Northstar chipsts. It
     uses single core Cortex-A7 and doesn't have SDU or local (TWD) timer. It
     was also stripped out of independent SPI controller and 2 GMACs.

Northstar uses SRAB which is some memory based (0x18007000) access to
switch register space.
BCM53573 uses different blocks & mappings and it doesn't include SRAB at
0x18007000. Accessing switch registers is handled over MDIO.
Florian: did my explanations help reviewing this patch? Would you ack it
now?

Re: [PATCH net-next] net: bgmac: support MDIO described in DT

From: Florian Fainelli <f.fainelli@gmail.com>
Date: 2021-09-30 23:04:45

On 9/30/21 7:29 AM, Rafał Miłecki wrote:
On 20.09.2021 19:57, Rafał Miłecki wrote:
quoted
On 20.09.2021 18:11, Florian Fainelli wrote:
quoted
I believe this leaks np and the use case is not exactly clear to me
here. AFAICT the Northstar SoCs have two MDIO controllers: one for
internal PHYs and one for external PHYs which how you would attach a
switch to the chip (in chipcommonA). Is 53573 somewhat different here?
What is the MDIO bus driver that is being used?
of_get_child_by_name() doesn't seem to increase refcount or anything and
I think it's how most drivers handle it. I don't think it should leak.

BCM53573 is a built with some older blocks. Please check:

4ebd50472899 ("ARM: BCM53573: Initial support for Broadcom BCM53573
SoCs")
     BCM53573 series is a new family with embedded wireless. By marketing
     people it's sometimes called Northstar but it uses different CPU
and has
     different architecture so we need a new symbol for it.
     Fortunately it shares some peripherals with other iProc based
SoCs so we
     will be able to reuse some drivers/bindings.

e90d2d51c412 ("ARM: BCM5301X: Add basic dts for BCM53573 based Tenda
AC9")
     BCM53573 seems to be low priced alternative for Northstar
chipsts. It
     uses single core Cortex-A7 and doesn't have SDU or local (TWD)
timer. It
     was also stripped out of independent SPI controller and 2 GMACs.

Northstar uses SRAB which is some memory based (0x18007000) access to
switch register space.
BCM53573 uses different blocks & mappings and it doesn't include SRAB at
0x18007000. Accessing switch registers is handled over MDIO.
Florian: did my explanations help reviewing this patch? Would you ack it
now?
Thanks for providing the background.

You still appear to be needing an of_node_put() after
of_mdiobus_register() because that function does increase the reference
count.
-- 
Florian

Re: [PATCH net-next] net: bgmac: support MDIO described in DT

From: Rafał Miłecki <zajec5@gmail.com>
Date: 2021-10-02 11:46:19

On 01.10.2021 01:04, Florian Fainelli wrote:
On 9/30/21 7:29 AM, Rafał Miłecki wrote:
quoted
On 20.09.2021 19:57, Rafał Miłecki wrote:
quoted
On 20.09.2021 18:11, Florian Fainelli wrote:
quoted
I believe this leaks np and the use case is not exactly clear to me
here. AFAICT the Northstar SoCs have two MDIO controllers: one for
internal PHYs and one for external PHYs which how you would attach a
switch to the chip (in chipcommonA). Is 53573 somewhat different here?
What is the MDIO bus driver that is being used?
of_get_child_by_name() doesn't seem to increase refcount or anything and
I think it's how most drivers handle it. I don't think it should leak.

BCM53573 is a built with some older blocks. Please check:

4ebd50472899 ("ARM: BCM53573: Initial support for Broadcom BCM53573
SoCs")
      BCM53573 series is a new family with embedded wireless. By marketing
      people it's sometimes called Northstar but it uses different CPU
and has
      different architecture so we need a new symbol for it.
      Fortunately it shares some peripherals with other iProc based
SoCs so we
      will be able to reuse some drivers/bindings.

e90d2d51c412 ("ARM: BCM5301X: Add basic dts for BCM53573 based Tenda
AC9")
      BCM53573 seems to be low priced alternative for Northstar
chipsts. It
      uses single core Cortex-A7 and doesn't have SDU or local (TWD)
timer. It
      was also stripped out of independent SPI controller and 2 GMACs.

Northstar uses SRAB which is some memory based (0x18007000) access to
switch register space.
BCM53573 uses different blocks & mappings and it doesn't include SRAB at
0x18007000. Accessing switch registers is handled over MDIO.
Florian: did my explanations help reviewing this patch? Would you ack it
now?
Thanks for providing the background.

You still appear to be needing an of_node_put() after
of_mdiobus_register() because that function does increase the reference
count.
I really can't find code increasing refcount.

I even attempted to runtime test it and I still can't see a leaking ref. See:

[    1.168863] bgmac_bcma bcma0:5: [bcma_mdio_mii_register] BEFORE count:2
[    1.176235] libphy: bcma_mdio mii bus: probed
[    1.181513] bcm53xx bcma_mdio-0-0:1e: found switch: BCM53125, rev 4
[    1.187936] bcm53xx bcma_mdio-0-0:1e: failed to register switch: -517
[    1.194610] bgmac_bcma bcma0:5: [bcma_mdio_mii_register]  AFTER count:2

diff --git a/drivers/net/ethernet/broadcom/bgmac-bcma-mdio.c b/drivers/net/ethernet/broadcom/bgmac-bcma-mdio.c
index 086739e4f..e52a3d8b7 100644
--- a/drivers/net/ethernet/broadcom/bgmac-bcma-mdio.c
+++ b/drivers/net/ethernet/broadcom/bgmac-bcma-mdio.c
@@ -233,11 +233,14 @@ struct mii_bus *bcma_mdio_mii_register(struct bgmac *bgmac)

         np = of_get_child_by_name(core->dev.of_node, "mdio");

+
+       dev_info(&core->dev, "[%s] BEFORE count:%d\n", __func__, refcount_read(&np->kobj.kref.refcount));
         err = of_mdiobus_register(mii_bus, np);
         if (err) {
                 dev_err(&core->dev, "Registration of mii bus failed\n");
                 goto err_free_bus;
         }
+       dev_info(&core->dev, "[%s]  AFTER count:%d\n", __func__, refcount_read(&np->kobj.kref.refcount));

         return mii_bus;
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