linux-kernel - Re: [PATCH v2 2/2] i2c: mark device nodes only in case of successful instantiation

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Date:   Mon, 17 Oct 2016 16:37:01 +0200
From:   Ralf Ramsauer <ralf@...ses-pyramidenbau.de>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Mark Brown <broonie@...nel.org>, Wolfram Sang <wsa@...-dreams.de>,
        Linux SPI <linux-spi@...r.kernel.org>,
        Linux I2C <linux-i2c@...r.kernel.org>,
        "linux-kernel @ vger . kernel . org" <linux-kernel@...r.kernel.org>,
        Pantelis Antoniou <pantelis.antoniou@...sulko.com>
Subject: Re: [PATCH v2 2/2] i2c: mark device nodes only in case of successful
 instantiation



On 10/17/2016 04:16 PM, Geert Uytterhoeven wrote:
> On Mon, Oct 17, 2016 at 3:59 PM, Ralf Ramsauer
> <ralf@...ses-pyramidenbau.de> wrote:
>> Instantiated I2C device nodes are marked with OF_POPULATE. This was
>> introduced in 4f001fd. On unloading, loaded device nodes will of course
>> be unmarked. The problem are nodes that fail during initialisation: If a
>> node fails, it won't be unloaded and hence not be unmarked.
>>
>> If a I2C driver module is unloaded and reloaded, it will skip nodes that
>> failed before.
>>
>> Skip device nodes that are already populated and mark them only in case
>> of success.
>>
>> Note that the same issue exists for SPI.
>>
>> Fixes: 4f001fd ("i2c: Mark instantiated device nodes with OF_POPULATE")
>> Signed-off-by: Ralf Ramsauer <ralf@...ses-pyramidenbau.de>
> 
> Reviewed-by: Geert Uytterhoeven <geert+renesas@...der.be>
> 
>> --- a/drivers/i2c/i2c-core.c
>> +++ b/drivers/i2c/i2c-core.c
> 
>> @@ -1695,7 +1696,14 @@ static void of_i2c_register_devices(struct i2c_adapter *adap)
>>         for_each_available_child_of_node(bus, node) {
>>                 if (of_node_test_and_set_flag(node, OF_POPULATED))
>>                         continue;
>> -               of_i2c_register_device(adap, node);
>> +
>> +               client = of_i2c_register_device(adap, node);
>> +               if (IS_ERR(client)) {
>> +                       dev_warn(&adap->dev,
>> +                                "Failed to create I2C device for %s\n",
>> +                                node->full_name);
> 
> I don't think there's a need to add this warning, as of_i2c_register_device()
> already prints messages in all failure paths.
So does of_register_spi_device(). And there's a dev_warn() in
of_spi_register_devices() as well...
But yes, I was also thinking of this.

Nevertheless, I added it as I thought this would keep both drivers
somehow consistent. And it's a very rare error case, though.

  Ralf
> 
>> +                       of_node_clear_flag(node, OF_POPULATED);
>> +               }
>>         }
> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds
> 

-- 
Ralf Ramsauer
PGP: 0x8F10049B