[PATCH] serial: 8250_dw: #ifdef out dw8250_acpi_match if ACPI isn't set

[PATCH] serial: 8250_dw: #ifdef out dw8250_acpi_match if ACPI isn't set

[Jisheng Zhang]

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=]

Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
---
 drivers/tty/serial/8250/8250_dw.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
index c89fafc972b6..bd43cbfd0783 100644
--- a/drivers/tty/serial/8250/8250_dw.c
+++ b/drivers/tty/serial/8250/8250_dw.c
@@ -637,6 +637,7 @@ static const struct of_device_id dw8250_of_match[] = {
 };
 MODULE_DEVICE_TABLE(of, dw8250_of_match);
 
+#ifdef CONFIG_ACPI
 static const struct acpi_device_id dw8250_acpi_match[] = {
 	{ "INT33C4", 0 },
 	{ "INT33C5", 0 },
@@ -651,6 +652,7 @@ static const struct acpi_device_id dw8250_acpi_match[] = {
 	{ },
 };
 MODULE_DEVICE_TABLE(acpi, dw8250_acpi_match);
+#endif
 
 static struct platform_driver dw8250_platform_driver = {
 	.driver = {
-- 
2.11.0

Re: [PATCH] serial: 8250_dw: #ifdef out dw8250_acpi_match if ACPI isn't set

[Greg KH]

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

greg k-h

Re: [PATCH] serial: 8250_dw: #ifdef out dw8250_acpi_match if ACPI isn't set

[Jisheng Zhang]

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:
> > 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