Re: [PATCH] of_mdio: Fix broken PHY IRQ in case of probe deferral

Geert Uytterhoeven
2017-05-18T16:13:29Z

Hi Andrew,

On Thu, May 18, 2017 at 6:09 PM, Andrew Lunn <andrew@lunn.ch> wrote:
> On Thu, May 18, 2017 at 02:59:05PM +0200, Geert Uytterhoeven wrote:
>> If an Ethernet PHY is initialized before the interrupt controller it is
>> connected to, a message like the following is printed:
>>
>> irq: no irq domain found for /interrupt-controller@e61c0000 !
>>
>> However, the actual error is ignored, leading to a non-functional (-1)
>> PHY interrupt later:
>>
>> Micrel KSZ8041RNLI ee700000.ethernet-ffffffff:01: attached PHY driver [Micrel KSZ8041RNLI] (mii_bus:phy_addr=ee700000.ethernet-ffffffff:01, irq=-1)
>>
>> Depending on whether the PHY driver will fall back to polling, Ethernet
>> may or may not work.
>>
>> To fix this:
>> 1. Switch of_mdiobus_register_phy() from irq_of_parse_and_map() to
>> of_irq_get().
>> Unlike the former, the latter returns -EPROBE_DEFER if the
>> interrupt controller is not yet available, so this condition can be
>> detected.
>> Other errors are handled the same as before, i.e. use the passed
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>> mdio->irq[addr] as interrupt.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>> 2. Propagate and handle errors from of_mdiobus_register_phy() and
>> of_mdiobus_register_device().
>>
>> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
>> ---
>> Seen on r8a7791/koelsch when using the new CPG/MSSR clock driver.
>> I assume it always happened on RZ/G1 in mainline.
>> ---
>> drivers/of/of_mdio.c | 39 +++++++++++++++++++++++++++------------
>> 1 file changed, 27 insertions(+), 12 deletions(-)
>>
>> diff --git a/drivers/of/of_mdio.c b/drivers/of/of_mdio.c
>> index 7e4c80f9b6cda0d3..f9ac2893f56184be 100644
>> --- a/drivers/of/of_mdio.c
>> +++ b/drivers/of/of_mdio.c
>> @@ -44,7 +44,7 @@ static int of_get_phy_id(struct device_node *device, u32 *phy_id)
>> return -EINVAL;
>> }
>>
>> -static void of_mdiobus_register_phy(struct mii_bus *mdio,
>> +static int of_mdiobus_register_phy(struct mii_bus *mdio,
>> struct device_node *child, u32 addr)
>> {
>> struct phy_device *phy;
>> @@ -60,9 +60,13 @@ static void of_mdiobus_register_phy(struct mii_bus *mdio,
>> else
>> phy = get_phy_device(mdio, addr, is_c45);
>> if (IS_ERR(phy))
>> - return;
>> + return PTR_ERR(phy);
>>
>> - rc = irq_of_parse_and_map(child, 0);
>> + rc = of_irq_get(child, 0);
>> + if (rc == -EPROBE_DEFER) {
>> + phy_device_free(phy);
>> + return rc;
>> + }
>
> Maybe this should be consistent. All other places there is an error,
> you return it. Here however, you only return the error if it is
> EPROBE_DEFER.

That's because of the "else" branch in the code below:

if (rc > 0) {
phy->irq = rc;
mdio->irq[addr] = rc;
} else {
phy->irq = mdio->irq[addr];
}

cfr. the marked part of the patch description.
I didn't want to change that behavior, as it's not clear to me why it's handled
that way.

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