Re: [PATCH] serial: pmac_zilog: don't init if zilog is not available

Laurent Vivier
2020-10-20T18:19:42Z

Le 20/10/2020 à 19:37, Greg KH a écrit :
> On Tue, Oct 20, 2020 at 06:37:41PM +0200, Laurent Vivier wrote:
>> Le 20/10/2020 à 18:28, Greg KH a écrit :
>>> On Tue, Oct 20, 2020 at 06:23:03PM +0200, Laurent Vivier wrote:
>>>> We can avoid to probe for the Zilog device (and generate ugly kernel warning)
>>>> if kernel is built for Mac but not on a Mac.
>>>>
>>>> Signed-off-by: Laurent Vivier <laurent@vivier.eu>
>>>> ---
>>>> drivers/tty/serial/pmac_zilog.c | 11 +++++++++++
>>>> 1 file changed, 11 insertions(+)
>>>>
>>>> diff --git a/drivers/tty/serial/pmac_zilog.c b/drivers/tty/serial/pmac_zilog.c
>>>> index 063484b22523..d1d2e55983c3 100644
>>>> --- a/drivers/tty/serial/pmac_zilog.c
>>>> +++ b/drivers/tty/serial/pmac_zilog.c
>>>> @@ -1867,6 +1867,12 @@ static struct platform_driver pmz_driver = {
>>>> static int __init init_pmz(void)
>>>> {
>>>> int rc, i;
>>>> +
>>>> +#ifdef CONFIG_MAC
>>>> + if (!MACH_IS_MAC)
>>>> + return -ENODEV;
>>>> +#endif
>>>
>>> Why is the #ifdef needed?
>>>
>>> We don't like putting #ifdef in .c files for good reasons. Can you make
>>> the api check for this work with and without that #ifdef needed?
>>
>> The #ifdef is needed because this file can be compiled for PowerMac and
>> m68k Mac. For PowerMac, the MACH_IS_MAC is not defined, so we need the
>> #ifdef.
>>
>> We need the MAC_IS_MAC because the same kernel can be used with several
>> m68k machines, so the init_pmz can be called on a m68k machine without
>> the zilog device (it's a multi-targets kernel).
>>
>> You can check it's the good way to do by looking inside:
>>
>> drivers/video/fbdev/valkyriefb.c +317
>> drivers/macintosh/adb.c +316
>>
>> That are two files used by both, mac and pmac.
>
> Why not fix it to work properly like other arch checks are done
I would be happy to do the same.

> Put it in a .h file and do the #ifdef there. Why is this "special"?

I don't know.

Do you mean something like:

drivers/tty/serial/pmac_zilog.h
...
#ifndef MACH_IS_MAC
#define MACH_IS_MAC (0)
#endif
...

drivers/tty/serial/pmac_zilog.c
...
static int __init pmz_console_init(void)
{
if (!MACH_IS_MAC)
return -ENODEV;
...

Thanks,
Laurent