On 2014-6-5 9:14, Zheng, Lv wrote:

Hi, Lee

quoted

From: Lee Jones [mailto:lee.jones at linaro.org]
Sent: Wednesday, June 04, 2014 8:52 PM
To: Rafael J. Wysocki

On Wed, 04 Jun 2014, Rafael J. Wysocki wrote:

quoted

On Wednesday, June 04, 2014 01:09:50 PM Lee Jones wrote:

quoted

Any drivers which support ACPI and Device Tree probing need to include
both respective header files.  Without this patch, if a driver is being
used on a platform which does not support ACPI and subsequently does not
have the config option enabled, but includes linux/acpi.h the build
breaks with:

  In file included from ../include/acpi/platform/acenv.h:150:0,
                   from ../include/acpi/acpi.h:56,
                   from ../include/linux/match.h:2,
                   from ../drivers/i2c/i2c-core.c:43:
  ../include/acpi/platform/aclinux.h:73:23:
   fatal error: asm/acenv.h: No such file or directory
   #include <asm/acenv.h>
                       ^

Note that:
In our tree:
<asm/acenv.h> is only included by <acpi/acpi.h>.
And <acpi/acpi.h> is only included by
1. <linux/acpi.h> when CONFIG_ACPI enabled
2. <linux/sfi_acpi.h> - this is x86 specific, we'll clean it up by implementing stubs for all ACPI external interfaces.
So there is no case we need to exclude <asm/acenv.h> when CONFIG_ACPI is not enabled.

I cannot find linux/match.h here.
If <linux/match.h> want to include ACPI features, it shouldn't include <acpi/acpi.h>, but should include <linux/acpi.h>.
Please refer to:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=8b48463f
And stop including <acpi/acpi.h> directly in any cases.

Ah, I agree, please ignore my previous email,
sorry for the noise.

Since it is very important to include <linux/acpi.h> but not <acpi/acpi.h>,
can we document it somewhere as the guidance? Then people will not
make such mistake :)

Thanks
Hanjun