[PATCH net 1/1] mdio_bus: fix mdio_register_device when RESET_CONTROLLER is disabled

[PATCH net 1/1] mdio_bus: fix mdio_register_device when RESET_CONTROLLER is disabled

[Marek Behún]

When CONFIG_RESET_CONTROLLER is disabled, the
devm_reset_control_get_exclusive function returns -ENOTSUPP. This is not
handled in subsequent check and then the mdio device fails to probe.

When CONFIG_RESET_CONTROLLER is enabled, its code checks in OF for reset
device, and since it is not present, returns -ENOENT. -ENOENT is handled.
Add -ENOTSUPP also.

This happened to me when upgrading kernel on Turris Omnia. You either
have to enable CONFIG_RESET_CONTROLLER or use this patch.

Signed-off-by: Marek Behún <marek.behun@nic.cz>
Fixes: 71dd6c0dff51b ("net: phy: add support for reset-controller")
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 drivers/net/phy/mdio_bus.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index 35876562e32a..c87cb8c0dac8 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -65,7 +65,8 @@ static int mdiobus_register_reset(struct mdio_device *mdiodev)
 		reset = devm_reset_control_get_exclusive(&mdiodev->dev,
 							 "phy");
 	if (IS_ERR(reset)) {
-		if (PTR_ERR(reset) == -ENOENT || PTR_ERR(reset) == -ENOSYS)
+		if (PTR_ERR(reset) == -ENOENT || PTR_ERR(reset) == -ENOSYS ||
+		    PTR_ERR(reset) == -ENOTSUPP)
 			reset = NULL;
 		else
 			return PTR_ERR(reset);
-- 
2.23.0

Re: [PATCH net 1/1] mdio_bus: fix mdio_register_device when RESET_CONTROLLER is disabled

[Andrew Lunn]

On Mon, Nov 18, 2019 at 07:15:05PM +0100, Marek Behún wrote:
> When CONFIG_RESET_CONTROLLER is disabled, the
> devm_reset_control_get_exclusive function returns -ENOTSUPP. This is not
> handled in subsequent check and then the mdio device fails to probe.
> 
> When CONFIG_RESET_CONTROLLER is enabled, its code checks in OF for reset
> device, and since it is not present, returns -ENOENT. -ENOENT is handled.
> Add -ENOTSUPP also.
> 
> This happened to me when upgrading kernel on Turris Omnia. You either
> have to enable CONFIG_RESET_CONTROLLER or use this patch.
> 
> Signed-off-by: Marek Behún <marek.behun@nic.cz>
> Fixes: 71dd6c0dff51b ("net: phy: add support for reset-controller")

This seems reasonable.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>

    Andrew

Re: [PATCH net 1/1] mdio_bus: fix mdio_register_device when RESET_CONTROLLER is disabled

[David Miller]

From: Marek Behún <marek.behun@nic.cz>
Date: Mon, 18 Nov 2019 19:15:05 +0100

> When CONFIG_RESET_CONTROLLER is disabled, the
> devm_reset_control_get_exclusive function returns -ENOTSUPP. This is not
> handled in subsequent check and then the mdio device fails to probe.
> 
> When CONFIG_RESET_CONTROLLER is enabled, its code checks in OF for reset
> device, and since it is not present, returns -ENOENT. -ENOENT is handled.
> Add -ENOTSUPP also.
> 
> This happened to me when upgrading kernel on Turris Omnia. You either
> have to enable CONFIG_RESET_CONTROLLER or use this patch.
> 
> Signed-off-by: Marek Behún <marek.behun@nic.cz>
> Fixes: 71dd6c0dff51b ("net: phy: add support for reset-controller")

Applied and queued up for -stable.

Re: [PATCH net 1/1] mdio_bus: fix mdio_register_device when RESET_CONTROLLER is disabled

[Andy Shevchenko]

On Mon, Nov 18, 2019 at 07:15:05PM +0100, Marek Behún wrote:
> When CONFIG_RESET_CONTROLLER is disabled, the
> devm_reset_control_get_exclusive function returns -ENOTSUPP. This is not
> handled in subsequent check and then the mdio device fails to probe.
> 
> When CONFIG_RESET_CONTROLLER is enabled, its code checks in OF for reset
> device, and since it is not present, returns -ENOENT. -ENOENT is handled.
> Add -ENOTSUPP also.
> 
> This happened to me when upgrading kernel on Turris Omnia. You either
> have to enable CONFIG_RESET_CONTROLLER or use this patch.

In the long term prospective shouldn't it use
reset_control_get_optional_exclusive() instead?

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH net 1/1] mdio_bus: fix mdio_register_device when RESET_CONTROLLER is disabled

[Geert Uytterhoeven]

[-- Attachment #1: Type: text/plain, Size: 4079 bytes --]

 	Hi all,

On Tue, 19 Nov 2019, Andy Shevchenko wrote:
> On Mon, Nov 18, 2019 at 07:15:05PM +0100, Marek Behún wrote:
>> When CONFIG_RESET_CONTROLLER is disabled, the
>> devm_reset_control_get_exclusive function returns -ENOTSUPP. This is not
>> handled in subsequent check and then the mdio device fails to probe.
>>
>> When CONFIG_RESET_CONTROLLER is enabled, its code checks in OF for reset
>> device, and since it is not present, returns -ENOENT. -ENOENT is handled.
>> Add -ENOTSUPP also.
>>
>> This happened to me when upgrading kernel on Turris Omnia. You either
>> have to enable CONFIG_RESET_CONTROLLER or use this patch.
>
> In the long term prospective shouldn't it use
> reset_control_get_optional_exclusive() instead?

I was thinking the same, hence I tried.

Without a reset (i.e. the returned reset is now NULL instead of
-ENOENT):

     WARNING: CPU: 1 PID: 120 at drivers/base/dd.c:519 really_probe+0xb0/0x314
     Modules linked in:
     CPU: 1 PID: 120 Comm: kworker/1:2 Not tainted 5.4.0-rc8-koelsch-08348-gbc6931ed2139022b-dirty #615
     Hardware name: Generic R-Car Gen2 (Flattened Device Tree)
     Workqueue: events deferred_probe_work_func
     [<c020e268>] (unwind_backtrace) from [<c020a428>] (show_stack+0x10/0x14)
     [<c020a428>] (show_stack) from [<c07a075c>] (dump_stack+0x88/0xa8)
     [<c07a075c>] (dump_stack) from [<c0220980>] (__warn+0xb8/0xd0)
     [<c0220980>] (__warn) from [<c0220a08>] (warn_slowpath_fmt+0x70/0x9c)
     [<c0220a08>] (warn_slowpath_fmt) from [<c05150b0>] (really_probe+0xb0/0x314)
     [<c05150b0>] (really_probe) from [<c0515598>] (driver_probe_device+0x13c/0x154)
     [<c0515598>] (driver_probe_device) from [<c0513784>] (bus_for_each_drv+0xa0/0xb4)
     [<c0513784>] (bus_for_each_drv) from [<c05153c0>] (__device_attach+0xac/0x124)
     [<c05153c0>] (__device_attach) from [<c05143f0>] (bus_probe_device+0x28/0x80)
     [<c05143f0>] (bus_probe_device) from [<c051227c>] (device_add+0x4d8/0x698)
     [<c051227c>] (device_add) from [<c0581110>] (phy_device_register+0x3c/0x74)
     [<c0581110>] (phy_device_register) from [<c0675efc>] (of_mdiobus_register_phy+0x144/0x17c)
     [<c0675efc>] (of_mdiobus_register_phy) from [<c06760f8>] (of_mdiobus_register+0x1c4/0x2d0)
     [<c06760f8>] (of_mdiobus_register) from [<c0589f18>] (sh_eth_drv_probe+0x778/0x8ac)
     [<c0589f18>] (sh_eth_drv_probe) from [<c0516ce8>] (platform_drv_probe+0x48/0x94)
     [<c0516ce8>] (platform_drv_probe) from [<c05151f8>] (really_probe+0x1f8/0x314)
     [<c05151f8>] (really_probe) from [<c0515598>] (driver_probe_device+0x13c/0x154)

The difference with the non-optional case is that
__devm_reset_control_get() registers a cleanup function if there's
no error condition, even for NULL (which is futile, will send a patch).

However, more importantly, mdiobus_register_reset() calls a devm_*()
function on "&mdiodev->dev" ("mdio_bus ee700000.ethernet-ffffffff:01"),
which is a different device than the one being probed
(("ee700000.ethernet"), see also the callstack below).
In fact "&mdiodev->dev" hasn't been probed yet, leading to the WARNING
when it is probed later.

     [<c0582de8>] (mdiobus_register_device) from [<c05810e0>] (phy_device_register+0xc/0x74)
     [<c05810e0>] (phy_device_register) from [<c0675ef4>] (of_mdiobus_register_phy+0x144/0x17c)
     [<c0675ef4>] (of_mdiobus_register_phy) from [<c06760f0>] (of_mdiobus_register+0x1c4/0x2d0)
     [<c06760f0>] (of_mdiobus_register) from [<c0589f0c>] (sh_eth_drv_probe+0x778/0x8ac)
     [<c0589f0c>] (sh_eth_drv_probe) from [<c0516ce8>] (platform_drv_probe+0x48/0x94)

Has commit 71dd6c0dff51b5f1 ("net: phy: add support for
reset-controller") been tested with an actual reset present?

Are Ethernet drivers not (no longer) allowed to register MDIO busses?

Thanks!

Gr{oetje,eeting}s,

 						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
 							    -- Linus Torvalds

Re: [PATCH net 1/1] mdio_bus: fix mdio_register_device when RESET_CONTROLLER is disabled

[Geert Uytterhoeven]

 	Hi all,

On Tue, 19 Nov 2019, Andy Shevchenko wrote:
> On Mon, Nov 18, 2019 at 07:15:05PM +0100, Marek Behún wrote:
>> When CONFIG_RESET_CONTROLLER is disabled, the
>> devm_reset_control_get_exclusive function returns -ENOTSUPP. This is not
>> handled in subsequent check and then the mdio device fails to probe.
>>
>> When CONFIG_RESET_CONTROLLER is enabled, its code checks in OF for reset
>> device, and since it is not present, returns -ENOENT. -ENOENT is handled.
>> Add -ENOTSUPP also.
>>
>> This happened to me when upgrading kernel on Turris Omnia. You either
>> have to enable CONFIG_RESET_CONTROLLER or use this patch.
>
> In the long term prospective shouldn't it use
> reset_control_get_optional_exclusive() instead?

I was thinking the same, hence I tried.

Without a reset (i.e. the returned reset is now NULL instead of
-ENOENT):

     WARNING: CPU: 1 PID: 120 at drivers/base/dd.c:519 really_probe+0xb0/0x314
     Modules linked in:
     CPU: 1 PID: 120 Comm: kworker/1:2 Not tainted 5.4.0-rc8-koelsch-08348-gbc6931ed2139022b-dirty #615
     Hardware name: Generic R-Car Gen2 (Flattened Device Tree)
     Workqueue: events deferred_probe_work_func
     [<c020e268>] (unwind_backtrace) from [<c020a428>] (show_stack+0x10/0x14)
     [<c020a428>] (show_stack) from [<c07a075c>] (dump_stack+0x88/0xa8)
     [<c07a075c>] (dump_stack) from [<c0220980>] (__warn+0xb8/0xd0)
     [<c0220980>] (__warn) from [<c0220a08>] (warn_slowpath_fmt+0x70/0x9c)
     [<c0220a08>] (warn_slowpath_fmt) from [<c05150b0>] (really_probe+0xb0/0x314)
     [<c05150b0>] (really_probe) from [<c0515598>] (driver_probe_device+0x13c/0x154)
     [<c0515598>] (driver_probe_device) from [<c0513784>] (bus_for_each_drv+0xa0/0xb4)
     [<c0513784>] (bus_for_each_drv) from [<c05153c0>] (__device_attach+0xac/0x124)
     [<c05153c0>] (__device_attach) from [<c05143f0>] (bus_probe_device+0x28/0x80)
     [<c05143f0>] (bus_probe_device) from [<c051227c>] (device_add+0x4d8/0x698)
     [<c051227c>] (device_add) from [<c0581110>] (phy_device_register+0x3c/0x74)
     [<c0581110>] (phy_device_register) from [<c0675efc>] (of_mdiobus_register_phy+0x144/0x17c)
     [<c0675efc>] (of_mdiobus_register_phy) from [<c06760f8>] (of_mdiobus_register+0x1c4/0x2d0)
     [<c06760f8>] (of_mdiobus_register) from [<c0589f18>] (sh_eth_drv_probe+0x778/0x8ac)
     [<c0589f18>] (sh_eth_drv_probe) from [<c0516ce8>] (platform_drv_probe+0x48/0x94)
     [<c0516ce8>] (platform_drv_probe) from [<c05151f8>] (really_probe+0x1f8/0x314)
     [<c05151f8>] (really_probe) from [<c0515598>] (driver_probe_device+0x13c/0x154)

The difference with the non-optional case is that
__devm_reset_control_get() registers a cleanup function if there's
no error condition, even for NULL (which is futile, will send a patch).

However, more importantly, mdiobus_register_reset() calls a devm_*()
function on "&mdiodev->dev" ("mdio_bus ee700000.ethernet-ffffffff:01"),
which is a different device than the one being probed
(("ee700000.ethernet"), see also the callstack below).
In fact "&mdiodev->dev" hasn't been probed yet, leading to the WARNING
when it is probed later.

     [<c0582de8>] (mdiobus_register_device) from [<c05810e0>] (phy_device_register+0xc/0x74)
     [<c05810e0>] (phy_device_register) from [<c0675ef4>] (of_mdiobus_register_phy+0x144/0x17c)
     [<c0675ef4>] (of_mdiobus_register_phy) from [<c06760f0>] (of_mdiobus_register+0x1c4/0x2d0)
     [<c06760f0>] (of_mdiobus_register) from [<c0589f0c>] (sh_eth_drv_probe+0x778/0x8ac)
     [<c0589f0c>] (sh_eth_drv_probe) from [<c0516ce8>] (platform_drv_probe+0x48/0x94)

Has commit 71dd6c0dff51b5f1 ("net: phy: add support for
reset-controller") been tested with an actual reset present?

Are Ethernet drivers not (no longer) allowed to register MDIO busses?

Thanks!

Gr{oetje,eeting}s,

 						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
 							    -- Linus Torvalds

Re: [PATCH net 1/1] mdio_bus: fix mdio_register_device when RESET_CONTROLLER is disabled

[Andrew Lunn]

> The difference with the non-optional case is that
> __devm_reset_control_get() registers a cleanup function if there's
> no error condition, even for NULL (which is futile, will send a patch).
> 
> However, more importantly, mdiobus_register_reset() calls a devm_*()
> function on "&mdiodev->dev" ("mdio_bus ee700000.ethernet-ffffffff:01"),
> which is a different device than the one being probed
> (("ee700000.ethernet"), see also the callstack below).
> In fact "&mdiodev->dev" hasn't been probed yet, leading to the WARNING
> when it is probed later.
> 
>     [<c0582de8>] (mdiobus_register_device) from [<c05810e0>] (phy_device_register+0xc/0x74)
>     [<c05810e0>] (phy_device_register) from [<c0675ef4>] (of_mdiobus_register_phy+0x144/0x17c)
>     [<c0675ef4>] (of_mdiobus_register_phy) from [<c06760f0>] (of_mdiobus_register+0x1c4/0x2d0)
>     [<c06760f0>] (of_mdiobus_register) from [<c0589f0c>] (sh_eth_drv_probe+0x778/0x8ac)
>     [<c0589f0c>] (sh_eth_drv_probe) from [<c0516ce8>] (platform_drv_probe+0x48/0x94)
> 
> Has commit 71dd6c0dff51b5f1 ("net: phy: add support for
> reset-controller") been tested with an actual reset present?
> 
> Are Ethernet drivers not (no longer) allowed to register MDIO busses?

That is not good. The devm_reset_control_get() call need replaces with
an unmanaged version, and a call to reset_control_put() added to
mdiobus_unregister_device().

David, could you look at this, it was a patch from you that added
this.

	Andrew

Re: [PATCH net 1/1] mdio_bus: fix mdio_register_device when RESET_CONTROLLER is disabled

[David Bauer]

Hello Andrew,

On 11/21/19 3:08 AM, Andrew Lunn wrote:
>> The difference with the non-optional case is that
>> __devm_reset_control_get() registers a cleanup function if there's
>> no error condition, even for NULL (which is futile, will send a patch).
>>
>> However, more importantly, mdiobus_register_reset() calls a devm_*()
>> function on "&mdiodev->dev" ("mdio_bus ee700000.ethernet-ffffffff:01"),
>> which is a different device than the one being probed
>> (("ee700000.ethernet"), see also the callstack below).
>> In fact "&mdiodev->dev" hasn't been probed yet, leading to the WARNING
>> when it is probed later.
>>
>>     [<c0582de8>] (mdiobus_register_device) from [<c05810e0>] (phy_device_register+0xc/0x74)
>>     [<c05810e0>] (phy_device_register) from [<c0675ef4>] (of_mdiobus_register_phy+0x144/0x17c)
>>     [<c0675ef4>] (of_mdiobus_register_phy) from [<c06760f0>] (of_mdiobus_register+0x1c4/0x2d0)
>>     [<c06760f0>] (of_mdiobus_register) from [<c0589f0c>] (sh_eth_drv_probe+0x778/0x8ac)
>>     [<c0589f0c>] (sh_eth_drv_probe) from [<c0516ce8>] (platform_drv_probe+0x48/0x94)
>>
>> Has commit 71dd6c0dff51b5f1 ("net: phy: add support for
>> reset-controller") been tested with an actual reset present?

I'm using it on a AR9132 board, however the mdio bus is probed before the
ethernet driver, hence why i was not experiencing this misbehavior.

>>
>> Are Ethernet drivers not (no longer) allowed to register MDIO busses?
> 
> That is not good. The devm_reset_control_get() call need replaces with
> an unmanaged version, and a call to reset_control_put() added to
> mdiobus_unregister_device().
> 
> David, could you look at this, it was a patch from you that added
> this.

I will prepare patches to fix this bug.

Best wishes
David

> 
> 	Andrew
> 

Re: [PATCH net 1/1] mdio_bus: fix mdio_register_device when RESET_CONTROLLER is disabled

[Geert Uytterhoeven]

Hi David,

On Thu, Nov 21, 2019 at 9:38 AM David Bauer <mail@david-bauer.net> wrote:
> On 11/21/19 3:08 AM, Andrew Lunn wrote:
> >> The difference with the non-optional case is that
> >> __devm_reset_control_get() registers a cleanup function if there's
> >> no error condition, even for NULL (which is futile, will send a patch).
> >>
> >> However, more importantly, mdiobus_register_reset() calls a devm_*()
> >> function on "&mdiodev->dev" ("mdio_bus ee700000.ethernet-ffffffff:01"),
> >> which is a different device than the one being probed
> >> (("ee700000.ethernet"), see also the callstack below).
> >> In fact "&mdiodev->dev" hasn't been probed yet, leading to the WARNING
> >> when it is probed later.
> >>
> >>     [<c0582de8>] (mdiobus_register_device) from [<c05810e0>] (phy_device_register+0xc/0x74)
> >>     [<c05810e0>] (phy_device_register) from [<c0675ef4>] (of_mdiobus_register_phy+0x144/0x17c)
> >>     [<c0675ef4>] (of_mdiobus_register_phy) from [<c06760f0>] (of_mdiobus_register+0x1c4/0x2d0)
> >>     [<c06760f0>] (of_mdiobus_register) from [<c0589f0c>] (sh_eth_drv_probe+0x778/0x8ac)
> >>     [<c0589f0c>] (sh_eth_drv_probe) from [<c0516ce8>] (platform_drv_probe+0x48/0x94)
> >>
> >> Has commit 71dd6c0dff51b5f1 ("net: phy: add support for
> >> reset-controller") been tested with an actual reset present?
>
> I'm using it on a AR9132 board, however the mdio bus is probed before the
> ethernet driver, hence why i was not experiencing this misbehavior.

Thank you, that explains it.

> >> Are Ethernet drivers not (no longer) allowed to register MDIO busses?
> >
> > That is not good. The devm_reset_control_get() call need replaces with
> > an unmanaged version, and a call to reset_control_put() added to
> > mdiobus_unregister_device().
> >
> > David, could you look at this, it was a patch from you that added
> > this.
>
> I will prepare patches to fix this bug.

Thanks!

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds