netdev - Re: [PATCH] net: tulip: turn compile-time warning into dev

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Date:	Thu, 19 Nov 2015 13:37:45 -0800
From:	Grant Grundler <grantgrundler@...il.com>
To:	Will Deacon <will.deacon@....com>
Cc:	Arnd Bergmann <arnd@...db.de>,
	"open list:TULIP NETWORK DRI..." <netdev@...r.kernel.org>,
	David Miller <davem@...emloft.net>, ard.biesheuvel@...aro.org,
	Grant Grundler <grundler@...isc-linux.org>
Subject: Re: [PATCH] net: tulip: turn compile-time warning into dev_warn()

On Thu, Nov 19, 2015 at 4:26 AM, Will Deacon <will.deacon@....com> wrote:
> On Thu, Nov 19, 2015 at 11:42:26AM +0100, Arnd Bergmann wrote:
>> The tulip driver causes annoying build-time warnings for allmodconfig
>> builds for all recent architectures:
>>
>> dec/tulip/winbond-840.c:910:2: warning: #warning Processor architecture undefined
>> dec/tulip/tulip_core.c:101:2: warning: #warning Processor architecture undefined!
>>
>> This is the last remaining warning for arm64, and I'd like to get rid of
>> it. We don't really know the cache line size, architecturally it would
>> be at least 16 bytes, but all implementations I found have 64 or 128
>> bytes. Configuring tulip for 32-byte lines as we do on ARM32 seems to
>> be the safe but slow default, and nobody who cares about performance these
>> days would use a tulip chip anyway, so we can just use that.
>>
>> To save the next person the job of trying to find out what this is for
>> and picking a default for their architecture just to kill off the warning,
>> I'm now removing the preprocessor #warning and turning it into a pr_warn
>> or dev_warn that prints the equivalent information when the driver gets
>> loaded.
>>
>> Signed-off-by: Arnd Bergmann <arnd@...db.de>
>>
>> diff --git a/drivers/net/ethernet/dec/tulip/tulip_core.c b/drivers/net/ethernet/dec/tulip/tulip_core.c
>> index ed41559bae77..b553409e04ad 100644
>> --- a/drivers/net/ethernet/dec/tulip/tulip_core.c
>> +++ b/drivers/net/ethernet/dec/tulip/tulip_core.c
>> @@ -98,8 +98,7 @@ static int csr0 = 0x01A00000 | 0x4800;
>>  #elif defined(__mips__)
>>  static int csr0 = 0x00200000 | 0x4000;
>>  #else
>> -#warning Processor architecture undefined!
>> -static int csr0 = 0x00A00000 | 0x4800;
>> +static int csr0;
>>  #endif
>>
>>  /* Operational parameters that usually are not changed. */
>> @@ -1982,6 +1981,12 @@ static int __init tulip_init (void)
>>       pr_info("%s", version);
>>  #endif
>>
>> +     if (!csr0) {
>> +             pr_warn("tulip: unknown CPU architecture, using default csr0\n");
>> +             /* default to 8 longword cache line alignment */
>> +             csr0 = 0x00A00000 | 0x4800;
>
> Maybe print "defaulting to 8 longword cache line alignment" instead of
> "default csr0"?

This is a good idea.

>> diff --git a/drivers/net/ethernet/dec/tulip/winbond-840.c b/drivers/net/ethernet/dec/tulip/winbond-840.c
>> index 9beb3d34d4ba..3c0e4d5c5fef 100644
>> --- a/drivers/net/ethernet/dec/tulip/winbond-840.c
>> +++ b/drivers/net/ethernet/dec/tulip/winbond-840.c
>> @@ -907,7 +907,7 @@ static void init_registers(struct net_device *dev)
>>  #elif defined(CONFIG_SPARC) || defined (CONFIG_PARISC) || defined(CONFIG_ARM)
>>       i |= 0x4800;
>>  #else
>> -#warning Processor architecture undefined
>> +     dev_warn(&dev->dev, "unknown CPU architecture, using default csr0 setting\n");
>>       i |= 0x4800;
>
> Then we could print the default csr0 value here.
>
> But, to be honest, this patch fixes a #warning on arm64 for a driver that
> I never expect to be used. So whatever you do to silence it:
>
>   Acked-by: Will Deacon <will.deacon@....com>

yeah - same here:
Acked-by: Grant Grundler <grundler@...isc-linux.org>

cheers,
grant

>
> /me waits for on-soc tulip integration.
>
> Will
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