| Message ID | 20231106154807.3866712-2-u.kleine-koenig@pengutronix.de (mailing list archive) |
|---|---|
| State | New, archived |
| 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 04:48:09PM +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/at91sam9_wdt: section mismatch in reference: at91wdt_driver+0x4 (section: .data) -> at91wdt_remove (section: .exit.text) > > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Reviewed-by: Guenter Roeck <linux@roeck-us.net>
On 06/11/2023 at 16:48, 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/at91sam9_wdt: section mismatch in reference: at91wdt_driver+0x4 (section: .data) -> at91wdt_remove (section: .exit.text) > > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com> > --- > drivers/watchdog/at91sam9_wdt.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) [..]
diff --git a/drivers/watchdog/at91sam9_wdt.c b/drivers/watchdog/at91sam9_wdt.c index b111b28acb94..507adb12754d 100644 --- a/drivers/watchdog/at91sam9_wdt.c +++ b/drivers/watchdog/at91sam9_wdt.c @@ -324,7 +324,7 @@ static inline int of_at91wdt_init(struct device_node *np, struct at91wdt *wdt) } #endif -static int __init at91wdt_probe(struct platform_device *pdev) +static int at91wdt_probe(struct platform_device *pdev) { int err; struct at91wdt *wdt; @@ -372,7 +372,7 @@ static int __init at91wdt_probe(struct platform_device *pdev) return 0; } -static int __exit at91wdt_remove(struct platform_device *pdev) +static int at91wdt_remove(struct platform_device *pdev) { struct at91wdt *wdt = platform_get_drvdata(pdev); watchdog_unregister_device(&wdt->wdd); @@ -393,14 +393,14 @@ MODULE_DEVICE_TABLE(of, at91_wdt_dt_ids); #endif static struct platform_driver at91wdt_driver = { - .remove = __exit_p(at91wdt_remove), + .probe = at91wdt_probe, + .remove = at91wdt_remove, .driver = { .name = "at91_wdt", .of_match_table = of_match_ptr(at91_wdt_dt_ids), }, }; - -module_platform_driver_probe(at91wdt_driver, at91wdt_probe); +module_platform_driver(at91wdt_driver); MODULE_AUTHOR("Renaud CERRATO <r.cerrato@til-technologies.fr>"); MODULE_DESCRIPTION("Watchdog driver for Atmel AT91SAM9x processors");
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/at91sam9_wdt: section mismatch in reference: at91wdt_driver+0x4 (section: .data) -> at91wdt_remove (section: .exit.text) Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> --- drivers/watchdog/at91sam9_wdt.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)