net: fec: properly guard irq coalesce setup

  Prior to the Fixes: commit, the initialization code went through the
same fec_enet_set_coalesce() function as used by ethtool, and that
function correctly checks whether the current variant has support for
irq coalescing.

Now that the initialization code instead calls fec_enet_itr_coal_set()
directly, that call needs to be guarded by a check for the
FEC_QUIRK_HAS_COALESCE bit.

Fixes: df727d4547de (net: fec: don't reset irq coalesce settings to defaults on "ip link up")
Reported-by: Greg Ungerer <gregungerer@westnet.com.au>
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
 drivers/net/ethernet/freescale/fec_main.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
  

On 12/5/22 12:46, Rasmus Villemoes wrote:
> Prior to the Fixes: commit, the initialization code went through the
> same fec_enet_set_coalesce() function as used by ethtool, and that
> function correctly checks whether the current variant has support for
> irq coalescing.
> 
> Now that the initialization code instead calls fec_enet_itr_coal_set()
> directly, that call needs to be guarded by a check for the
> FEC_QUIRK_HAS_COALESCE bit.
> 
> Fixes: df727d4547de (net: fec: don't reset irq coalesce settings to defaults on "ip link up")
> Reported-by: Greg Ungerer <gregungerer@westnet.com.au>
> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>

Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>

> ---
>   drivers/net/ethernet/freescale/fec_main.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
> index 2ca2b61b451f..23e1a94b9ce4 100644
> --- a/drivers/net/ethernet/freescale/fec_main.c
> +++ b/drivers/net/ethernet/freescale/fec_main.c
> @@ -1220,7 +1220,8 @@ fec_restart(struct net_device *ndev)
>   		writel(0, fep->hwp + FEC_IMASK);
>   
>   	/* Init the interrupt coalescing */
> -	fec_enet_itr_coal_set(ndev);
> +	if (fep->quirks & FEC_QUIRK_HAS_COALESCE)
> +		fec_enet_itr_coal_set(ndev);

There is already a guard in fec_enet_set_coalesce() so this makes sense, 
thanks!
  

Am Montag, 5. Dezember 2022, 21:46:04 CET schrieb Rasmus Villemoes:
> Prior to the Fixes: commit, the initialization code went through the
> same fec_enet_set_coalesce() function as used by ethtool, and that
> function correctly checks whether the current variant has support for
> irq coalescing.
> 
> Now that the initialization code instead calls fec_enet_itr_coal_set()
> directly, that call needs to be guarded by a check for the
> FEC_QUIRK_HAS_COALESCE bit.
> 
> Fixes: df727d4547de (net: fec: don't reset irq coalesce settings to defaults
> on "ip link up") Reported-by: Greg Ungerer <gregungerer@westnet.com.au>
> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
> ---
>  drivers/net/ethernet/freescale/fec_main.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/freescale/fec_main.c
> b/drivers/net/ethernet/freescale/fec_main.c index
> 2ca2b61b451f..23e1a94b9ce4 100644
> --- a/drivers/net/ethernet/freescale/fec_main.c
> +++ b/drivers/net/ethernet/freescale/fec_main.c
> @@ -1220,7 +1220,8 @@ fec_restart(struct net_device *ndev)
>  		writel(0, fep->hwp + FEC_IMASK);
> 
>  	/* Init the interrupt coalescing */
> -	fec_enet_itr_coal_set(ndev);
> +	if (fep->quirks & FEC_QUIRK_HAS_COALESCE)
> +		fec_enet_itr_coal_set(ndev);
>  }
> 
>  static int fec_enet_ipc_handle_init(struct fec_enet_private *fep)

I'm wondering if this check should be added to fec_enet_itr_coal_set() 
instead. Right now any additional caller has to do it's own check for 
FEC_QUIRK_HAS_COALESCE, so why not do check in fec_enet_itr_coal_set?
But I'm okay with this change as well.

Best regards,
Alexander
  

On 06/12/2022 07.16, Alexander Stein wrote:
> Am Montag, 5. Dezember 2022, 21:46:04 CET schrieb Rasmus Villemoes:
>> Prior to the Fixes: commit, the initialization code went through the
>> same fec_enet_set_coalesce() function as used by ethtool, and that
>> function correctly checks whether the current variant has support for
>> irq coalescing.
>>
>> Now that the initialization code instead calls fec_enet_itr_coal_set()
>> directly, that call needs to be guarded by a check for the
>> FEC_QUIRK_HAS_COALESCE bit.
>>
>> Fixes: df727d4547de (net: fec: don't reset irq coalesce settings to defaults
>> on "ip link up") Reported-by: Greg Ungerer <gregungerer@westnet.com.au>
>> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
>> ---
>>  drivers/net/ethernet/freescale/fec_main.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/ethernet/freescale/fec_main.c
>> b/drivers/net/ethernet/freescale/fec_main.c index
>> 2ca2b61b451f..23e1a94b9ce4 100644
>> --- a/drivers/net/ethernet/freescale/fec_main.c
>> +++ b/drivers/net/ethernet/freescale/fec_main.c
>> @@ -1220,7 +1220,8 @@ fec_restart(struct net_device *ndev)
>>  		writel(0, fep->hwp + FEC_IMASK);
>>
>>  	/* Init the interrupt coalescing */
>> -	fec_enet_itr_coal_set(ndev);
>> +	if (fep->quirks & FEC_QUIRK_HAS_COALESCE)
>> +		fec_enet_itr_coal_set(ndev);
>>  }
>>
>>  static int fec_enet_ipc_handle_init(struct fec_enet_private *fep)
> 
> I'm wondering if this check should be added to fec_enet_itr_coal_set() 
> instead. Right now any additional caller has to do it's own check for 
> FEC_QUIRK_HAS_COALESCE, so why not do check in fec_enet_itr_coal_set?

Yeah, I did consider that (see
https://lore.kernel.org/netdev/72eb4e63-10a8-702b-1113-7588fcade9fc@rasmusvillemoes.dk/).
But in the end I decided against it, for various small reasons.
Primarily my thinking was that while this caller is obviously ok with
fec_enet_itr_coal_set() just silently being a no-op, it's not clear that
some future caller wouldn't have to check the bit themselves and return
-EOPNOTSUPP or some other error just like the ethtool method does. Of
course we could also make fec_enet_itr_coal_set() not return void, but
then it's a whole different refactoring and definitely not for post-rc8.

But also, the above was what I had sent out as a "something like this?"
and tested on my own hardware before heading home, and due to the
imminent release, I wanted to send out the patch ASAP.

Rasmus
  

Hello:

This patch was applied to netdev/net.git (master)
by Jakub Kicinski <kuba@kernel.org>:

On Mon,  5 Dec 2022 21:46:04 +0100 you wrote:
> Prior to the Fixes: commit, the initialization code went through the
> same fec_enet_set_coalesce() function as used by ethtool, and that
> function correctly checks whether the current variant has support for
> irq coalescing.
> 
> Now that the initialization code instead calls fec_enet_itr_coal_set()
> directly, that call needs to be guarded by a check for the
> FEC_QUIRK_HAS_COALESCE bit.
> 
> [...]

Here is the summary with links:
  - net: fec: properly guard irq coalesce setup
    https://git.kernel.org/netdev/net/c/7e6303567ce3

You are awesome, thank you!