netdev - Re: [PATCH] of_mdio: fix phy interrupt passing

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Message-ID: <53032A97.8050201@codethink.co.uk>
Date:	Tue, 18 Feb 2014 09:40:39 +0000
From:	Ben Dooks <ben.dooks@...ethink.co.uk>
To:	Grant Likely <grant.likely@...aro.org>
CC:	linux-kernel@...ts.codethink.co.uk, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	linux-sh@...r.kernel.org, sergei.shtylyov@...entembedded.com
Subject: Re: [PATCH] of_mdio: fix phy interrupt passing

On 18/02/14 09:30, Grant Likely wrote:
> On Mon, 17 Feb 2014 16:29:40 +0000, Ben Dooks <ben.dooks@...ethink.co.uk> wrote:
>> The of_mdiobus_register_phy() is not setting phy->irq this causing
>> some drivers to incorrectly assume that the PHY does not have an
>> IRQ associated with it or install an interrupt handler for the
>> PHY.
>>
>> Simplify the code setting irq and set the phy->irq at the same
>> time so that the case if mdio->irq is not NULL is easier to read.
>>
>> This fixes the issue:
>>   net eth0: attached PHY 1 (IRQ -1) to driver Micrel KSZ8041RNLI
>>
>> to the correct:
>>   net eth0: attached PHY 1 (IRQ 416) to driver Micrel KSZ8041RNLI
>>
>> Signed-off-by: Ben Dooks <ben.dooks@...ethink.co.uk>
>> ---
>>   drivers/of/of_mdio.c | 12 ++++++------
>>   1 file changed, 6 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/of/of_mdio.c b/drivers/of/of_mdio.c
>> index 875b7b6..7b3e7b0 100644
>> --- a/drivers/of/of_mdio.c
>> +++ b/drivers/of/of_mdio.c
>> @@ -44,7 +44,7 @@ static int of_mdiobus_register_phy(struct mii_bus *mdio, struct device_node *chi
>>   {
>>   	struct phy_device *phy;
>>   	bool is_c45;
>> -	int rc, prev_irq;
>> +	int rc;
>>   	u32 max_speed = 0;
>>
>>   	is_c45 = of_device_is_compatible(child,
>> @@ -55,11 +55,11 @@ static int of_mdiobus_register_phy(struct mii_bus *mdio, struct device_node *chi
>>   		return 1;
>>
>>   	if (mdio->irq) {
>> -		prev_irq = mdio->irq[addr];
>> -		mdio->irq[addr] =
>> -			irq_of_parse_and_map(child, 0);
>> -		if (!mdio->irq[addr])
>> -			mdio->irq[addr] = prev_irq;
>
> I cannot for the life for me remeber why the code was structured that
> way. Your change is better.
>
>> +		rc = irq_of_parse_and_map(child, 0);
>> +		if (rc > 0) {
>> +			mdio->irq[addr] = rc;
>> +			phy->irq = rc;
>> +		}
>>   	}
>
> The outer if is merely protecting against no irq array being allocated
> for the bus. Would not the following be better:
>
> 	rc = irq_of_parse_and_map(child, 0);
> 	if (rc > 0) {
> 		phy->irq = rc;
> 		if (mdio->irq)
> 			mdio->irq[addr] = rc;
> 	}

Thanks, that makes sense, although we've both failed to work
out if mdio->irq is set, and rc <= 0 case, so:

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

I think that covers all cases. This does rely on mdio->irq
being initialised to PHY_POLL if allocated.

Once this is in, it may be easier then to not allocate
mdio->irq for the OF case by default unless the driver
registering the PHY knows it has the interrupt number(s)
for the PHY already.

-- 
Ben Dooks				http://www.codethink.co.uk/
Senior Engineer				Codethink - Providing Genius
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