| Message ID | 20231106154807.3866712-3-u.kleine-koenig@pengutronix.de (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | watchdog: Drop platform_driver_probe() and convert to platform remove callback returning void (part II) | expand |
On Mon, Nov 06, 2023 at 04:48:10PM +0100, Uwe Kleine-König wrote: > On today's platforms the benefit of platform_driver_probe() isn't that > relevant any more. It allows to drop some code after booting (or module > loading) for .probe() and discard the .remove() function completely if > the driver is built-in. This typically saves a few 100k. > > The downside of platform_driver_probe() is that the driver cannot be > bound and unbound at runtime which is ancient and also slightly > complicates testing. There are also thoughts to deprecate > platform_driver_probe() because it adds some complexity in the driver > core for little gain. Also many drivers don't use it correctly. This > driver for example misses to mark the driver struct with __refdata which > is needed to suppress a (W=1) modpost warning: > > WARNING: modpost: drivers/watchdog/txx9wdt: section mismatch in reference: txx9wdt_driver+0x4 (section: .data) -> txx9wdt_remove (section: .exit.text) > > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Reviewed-by: Guenter Roeck <linux@roeck-us.net>
diff --git a/drivers/watchdog/txx9wdt.c b/drivers/watchdog/txx9wdt.c index 89a54b6645bd..f900c519ed63 100644 --- a/drivers/watchdog/txx9wdt.c +++ b/drivers/watchdog/txx9wdt.c @@ -98,7 +98,7 @@ static struct watchdog_device txx9wdt = { .ops = &txx9wdt_ops, }; -static int __init txx9wdt_probe(struct platform_device *dev) +static int txx9wdt_probe(struct platform_device *dev) { int ret; @@ -145,7 +145,7 @@ static int __init txx9wdt_probe(struct platform_device *dev) return ret; } -static int __exit txx9wdt_remove(struct platform_device *dev) +static int txx9wdt_remove(struct platform_device *dev) { watchdog_unregister_device(&txx9wdt); clk_disable_unprepare(txx9_imclk); @@ -159,14 +159,14 @@ static void txx9wdt_shutdown(struct platform_device *dev) } static struct platform_driver txx9wdt_driver = { - .remove = __exit_p(txx9wdt_remove), + .probe = txx9wdt_probe, + .remove = txx9wdt_remove, .shutdown = txx9wdt_shutdown, .driver = { .name = "txx9wdt", }, }; - -module_platform_driver_probe(txx9wdt_driver, txx9wdt_probe); +module_platform_driver(txx9wdt_driver); MODULE_DESCRIPTION("TXx9 Watchdog Driver"); MODULE_LICENSE("GPL");
On today's platforms the benefit of platform_driver_probe() isn't that relevant any more. It allows to drop some code after booting (or module loading) for .probe() and discard the .remove() function completely if the driver is built-in. This typically saves a few 100k. The downside of platform_driver_probe() is that the driver cannot be bound and unbound at runtime which is ancient and also slightly complicates testing. There are also thoughts to deprecate platform_driver_probe() because it adds some complexity in the driver core for little gain. Also many drivers don't use it correctly. This driver for example misses to mark the driver struct with __refdata which is needed to suppress a (W=1) modpost warning: WARNING: modpost: drivers/watchdog/txx9wdt: section mismatch in reference: txx9wdt_driver+0x4 (section: .data) -> txx9wdt_remove (section: .exit.text) Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> --- drivers/watchdog/txx9wdt.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)