On Thu, Aug 7, 2014 at 7:21 PM, Paul Walmsley <paul@xxxxxxxxx> wrote:
>
> It's commit a71e3c37960ce5f9c6a519bc1215e3ba9fa83e75:
>
> Author: Ezequiel Garcia <ezequiel.garcia@xxxxxxxxxxxxxxxxxx>
> Date: Wed Jul 23 16:47:31 2014 -0300
>
> net: phy: Set the driver when registering an MDIO bus device
>
> mdiobus_register() registers a device which is already bound to a driver.
> Hence, the driver pointer should be set properly in order to track down
> the driver associated to the MDIO bus.
>
> This will be used to allow ethernet driver to pin down a MDIO bus driver,
> preventing it from being unloaded while the PHY device is running.
>
> Reviewed-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
> Tested-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
> Signed-off-by: Ezequiel Garcia <ezequiel.garcia@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
>
>
> What's bad is that this went in late during v3.16-rc fixes. So now v3.16
> itself is broken, and there's no way to fix it.
I have sent a patch reverting this commit and it is in mainline now.
It will reach 3.16.1:
commit ce7991e8198b80eb6b4441b6f6114bea4a665d66
Author: Fabio Estevam <fabio.estevam@xxxxxxxxxxxxx>
Date: Tue Aug 5 08:13:42 2014 -0300
Revert "net: phy: Set the driver when registering an MDIO bus device"
Commit a71e3c37960ce5f9 ("net: phy: Set the driver when
registering an MDIO bus
device") caused the following regression on the fec driver:
root@imx6qsabresd:~# echo mem > /sys/power/state
PM: Syncing filesystems ... done.
Freezing user space processes ... (elapsed 0.003 seconds) done.
Freezing remaining freezable tasks ... (elapsed 0.002 seconds) done.
Unable to handle kernel NULL pointer dereference at virtual address 0000002c
pgd = bcd14000
[0000002c] *pgd=4d9e0831, *pte=00000000, *ppte=00000000
Internal error: Oops: 17 [#1] SMP ARM
Modules linked in:
CPU: 0 PID: 617 Comm: sh Not tainted 3.16.0 #17
task: bc0c4e00 ti: bceb6000 task.ti: bceb6000
PC is at fec_suspend+0x10/0x70
LR is at dpm_run_callback.isra.7+0x34/0x6c
pc : [<803f8a98>] lr : [<80361f44>] psr: 600f0013
sp : bceb7d70 ip : bceb7d88 fp : bceb7d84
r10: 8091523c r9 : 00000000 r8 : bd88f478
r7 : 803f8a88 r6 : 81165988 r5 : 00000000 r4 : 00000000
r3 : 00000000 r2 : 00000000 r1 : bd88f478 r0 : bd88f478
Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user
Control: 10c5387d Table: 4cd1404a DAC: 00000015
Process sh (pid: 617, stack limit = 0xbceb6240)
Stack: (0xbceb7d70 to 0xbceb8000)
....
The problem with the original commit is explained by Russell King:
"It has the effect (as can be seen from the oops) of attaching the MDIO bus
device (itself is a bus-less device) to the platform driver, which means
that if the platform driver supports power management, it will be called
to power manage the MDIO bus device.
Moreover, drivers do not expect to be called for power management
operations for devices which they haven't probed, and certainly not for
devices which aren't part of the same bus that the driver is registered
against."
This reverts commit a71e3c37960ce5f9c6a519bc1215e3ba9fa83e75.
Cc: <stable@xxxxxxxxxxxxxxx> #3.16
Signed-off-by: Fabio Estevam <fabio.estevam@xxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
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