linux-kernel - Re: [PATCH net] net: dsa: microchip: fix probe of I2C-connected KSZ8563

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Message-ID: <a2d900dd-7a03-1185-75be-a4ac54ccf6e8@pengutronix.de>
Date:   Fri, 20 Jan 2023 08:57:03 +0100
From:   Ahmad Fatoum <a.fatoum@...gutronix.de>
To:     Arun.Ramadoss@...rochip.com, olteanv@...il.com,
        UNGLinuxDriver@...rochip.com, andrew@...n.ch, f.fainelli@...il.com,
        kuba@...nel.org, Woojung.Huh@...rochip.com, davem@...emloft.net
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel@...gutronix.de, pabeni@...hat.com, ore@...gutronix.de,
        edumazet@...gle.com
Subject: Re: [PATCH net] net: dsa: microchip: fix probe of I2C-connected
 KSZ8563

Hello Arun,

On 20.01.23 08:01, Arun.Ramadoss@...rochip.com wrote:
> Hi Ahmad,
> On Thu, 2023-01-19 at 14:10 +0100, Ahmad Fatoum wrote:
>> [You don't often get email from a.fatoum@...gutronix.de. Learn why
>> this is important at https://aka.ms/LearnAboutSenderIdentification ]
>>
>> EXTERNAL EMAIL: Do not click links or open attachments unless you
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>>
>> Starting with commit eee16b147121 ("net: dsa: microchip: perform the
>> compatibility check for dev probed"), the KSZ switch driver now bails
>> out if it thinks the DT compatible doesn't match the actual chip:
>>
>>   ksz9477-switch 1-005f: Device tree specifies chip KSZ9893 but found
>>   KSZ8563, please fix it!
>>
>> Problem is that the "microchip,ksz8563" compatible is associated
>> with ksz_switch_chips[KSZ9893]. Same issue also affected the SPI
>> driver
>> for the same switch chip and was fixed in commit b44908095612
>> ("net: dsa: microchip: add separate struct ksz_chip_data for KSZ8563
>> chip").
>>
>> Reuse ksz_switch_chips[KSZ8563] introduced in aforementioned commit
>> to get I2C-connected KSZ8563 probing again.
>>
>> Fixes: eee16b147121 ("net: dsa: microchip: perform the compatibility
>> check for dev probed")
> 
> In this commit, there is no KSZ8563 member in struct ksz_switch_chips.
> Whether the fixes should be to this commit "net: dsa: microchip: add
> separate struct ksz_chip_data for KSZ8563" where the member is
> introduced.

I disagree. eee16b147121 introduced the check that made my device
not probe anymore, so that's what's referenced in Fixes:. Commit
b44908095612 should have had a Fixes: pointing at eee16b147121
as well, so users don't miss it. But if they miss it, they
will notice this at build-time anyway.

Cheers,
Ahmad

> 
>> chip
>> Signed-off-by: Ahmad Fatoum <a.fatoum@...gutronix.de>
>> ---
>>  drivers/net/dsa/microchip/ksz9477_i2c.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/dsa/microchip/ksz9477_i2c.c
>> b/drivers/net/dsa/microchip/ksz9477_i2c.c
>> index c1a633ca1e6d..e315f669ec06 100644
>> --- a/drivers/net/dsa/microchip/ksz9477_i2c.c
>> +++ b/drivers/net/dsa/microchip/ksz9477_i2c.c
>> @@ -104,7 +104,7 @@ static const struct of_device_id ksz9477_dt_ids[]
>> = {
>>         },
>>         {
>>                 .compatible = "microchip,ksz8563",
>> -               .data = &ksz_switch_chips[KSZ9893]
>> +               .data = &ksz_switch_chips[KSZ8563]
>>         },
>>         {
>>                 .compatible = "microchip,ksz9567",
>> --
>> 2.30.2
>>

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