Hi Greg,

On Fri, 23 Dec 2016 19:09:23 +0100 Greg KH wrote:

On Fri, Dec 23, 2016 at 08:33:55PM +0800, Jisheng Zhang wrote:

quoted

dw8250_acpi_match is used only when ACPI is enabled. Fix the following
gcc warning when W=1 is set:

drivers/tty/serial/8250/8250_dw.c:640:36: warning: 'dw8250_acpi_match'
defined but not used [-Wunused-const-variable=]  

Don't set W=1 then, this type of "fix" is foolish and is just going to
make code messier, sorry.

Per my understanding of commit c9c6837d3931 ("kbuild: move
-Wunused-const-variable to W=1 warning level"), "Once we have eliminated
the majority of the warnings for both, we can put them back into the
default list.", so we'll have such warning one day without W=1 in the
future.

And FWICT, other devices drivers which could be used in ACPI and DT also
add the "#ifdef ACPI" to the acpi match table, such as:

drivers/ata/ahci_xgene.c
drivers/dma/dw/platform.c
drivers/i2c/busses/i2c-designware-platdrv.c
drivers/hid/i2c-hid/i2c-hid.c
drivers/usb/dwc3/core.c

Thanks,
Jisheng