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

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Message-ID: <671d564e-db1c-ed61-3538-97dd1916714d@gmail.com>
Date:   Tue, 31 Jan 2023 11:38:36 +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 11:05, 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
have GXL HW and we didn't want to submit a patch just based on speculation.

>> Reviewed-by: Heiner Kallweit <hkallweit1@...il.com>
>> Signed-off-by: Chris Healy <healych@...zon.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,
>>  	},
>>  };
>