netdev - Re: [PATCH v3] net: phy: meson-gxl: Add generic dummy stubs for MMD register access

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Message-ID: <74963e76-e417-c044-bd1b-7c6d53fc6994@gmail.com>
Date:   Tue, 31 Jan 2023 13:08:40 +0100
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Jerome Brunet <jbrunet@...libre.com>, cphealy@...il.com,
        andrew@...n.ch, linux@...linux.org.uk, davem@...emloft.net,
        neil.armstrong@...aro.org, khilman@...libre.com,
        netdev@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org,
        jeremy.wang@...ogic.com
Cc:     Chris Healy <healych@...zon.com>
Subject: Re: [PATCH v3] net: phy: meson-gxl: Add generic dummy stubs for MMD
 register access

On 31.01.2023 11:59, Jerome Brunet wrote:
> 
> On Tue 31 Jan 2023 at 11:38, Heiner Kallweit <hkallweit1@...il.com> wrote:
> 
>> On 31.01.2023 11:05, Jerome Brunet wrote:
>>>
>>> On Mon 30 Jan 2023 at 15:14, Chris Healy <cphealy@...il.com> wrote:
>>>
>>>> From: Chris Healy <healych@...zon.com>
>>>>
>>>> The Meson G12A Internal PHY does not support standard IEEE MMD extended
>>>> register access, therefore add generic dummy stubs to fail the read and
>>>> write MMD calls. This is necessary to prevent the core PHY code from
>>>> erroneously believing that EEE is supported by this PHY even though this
>>>> PHY does not support EEE, as MMD register access returns all FFFFs.
>>>
>>> This is definitely something that should be done, Thx !
>>>
>>>>
>>>> Fixes: 5c3407abb338 ("net: phy: meson-gxl: add g12a support")
>>>
>>> This commit does not seems appropriate, especially since only the GXL ops
>>> are changed, not the g12a variant.
>>>
>> The diff is a little bit misleading. The patch affects the G12A PHY.
>>
>>> This brings a 2nd point, any reason for not changing the g12 variant ?
>>> I'm fairly confident it does support EEE either.
>>>
>> Supposedly it's a typo and you mean "doesn't". Neither Chris nor me
> 
> Indeed ;)
> 
>> have GXL HW and we didn't want to submit a patch just based on speculation.
>>
> 
> Ah - Ok.
> I've tested something similar recently while working on the PHY.
> I confirm that both GXL and G12a should stub those calls.
> 
> ... maybe in separate patches to help stable backports.
> 
> Do you want to handle this or should I ?
> 
I can take it, will add your Suggested-by.

>>>> Reviewed-by: Heiner Kallweit <hkallweit1@...il.com>
>>>> Signed-off-by: Chris Healy <healych@...zon.com>
>>>>
> 
> Reviewed-by: Jerome Brunet <jbrunet@...libre.com>
> 
>>>> ---
>>>>
>>>> Changes in v3:
>>>> * Add reviewed-by
>>>> Change in v2:
>>>> * Add fixes tag
>>>>
>>>>  drivers/net/phy/meson-gxl.c | 2 ++
>>>>  1 file changed, 2 insertions(+)
>>>>
>>>> diff --git a/drivers/net/phy/meson-gxl.c b/drivers/net/phy/meson-gxl.c
>>>> index c49062ad72c6..5e41658b1e2f 100644
>>>> --- a/drivers/net/phy/meson-gxl.c
>>>> +++ b/drivers/net/phy/meson-gxl.c
>>>> @@ -271,6 +271,8 @@ static struct phy_driver meson_gxl_phy[] = {
>>>>  		.handle_interrupt = meson_gxl_handle_interrupt,
>>>>  		.suspend        = genphy_suspend,
>>>>  		.resume         = genphy_resume,
>>>> +		.read_mmd	= genphy_read_mmd_unsupported,
>>>> +		.write_mmd	= genphy_write_mmd_unsupported,
>>>>  	},
>>>>  };
>>>
>