On Fri, Jan 25, 2019 at 5:20 AM Feng Tang <[email protected]> wrote: > > Asynchronous driver probing can help much on kerenl fastboot, and > this option can provide a flexible way to optimize and quickly verify > async driver probe. > > Also it will help in below cases: > * Some driver actually covers several family of HWs, some of which > could use async probling while others don't. So we can't simply > turn on the PROBE_PREFER_ASYNCHRONOUS flag in driver, but use this > cmdline option, like igb driver discussed at > https://www.spinics.net/lists/netdev/msg545986.html > > * For SOC (System on Chip) with multiple spi or i2c controllers, most > of the slave spi/i2c devices will be assigned with fixed controller > number, which prevents these spi/i2c controller drivers to be async > probed. For plaforms not using these spi/i2c slave devices, they can > use this cmdline option to benefit from the async probing. > > Suggested-by: Alexander Duyck <[email protected]>
Actually instead of using my personal email I would prefer if you used "[email protected]". > Signed-off-by: Feng Tang <[email protected]> > --- > drivers/base/dd.c | 22 ++++++++++++++++++++++ > 1 file changed, 22 insertions(+) > > diff --git a/drivers/base/dd.c b/drivers/base/dd.c > index 8ac10af..1f257561 100644 > --- a/drivers/base/dd.c > +++ b/drivers/base/dd.c > @@ -57,6 +57,10 @@ static atomic_t deferred_trigger_count = ATOMIC_INIT(0); > static struct dentry *deferred_devices; > static bool initcalls_done; > > +/* Save the async probe drivers' name from kernel cmdline */ > +#define ASYNC_DRV_NAMES_MAX_LEN 256 > +static char async_probe_drv_names[ASYNC_DRV_NAMES_MAX_LEN]; > + > /* > * In some cases, like suspend to RAM or hibernation, It might be reasonable > * to prohibit probing of devices as it could be unsafe. > @@ -674,8 +678,26 @@ int driver_probe_device(struct device_driver *drv, > struct device *dev) > return ret; > } > > +static inline bool cmdline_requested_async_probing(const char *drv_name) > +{ > + return parse_option_str(async_probe_drv_names, drv_name); > +} > + > +static int __init save_async_options(char *buf) > +{ > + if (strlen(buf) >= ASYNC_DRV_NAMES_MAX_LEN) > + printk(KERN_WARNING "Too long list for > async_probe_drv_names!"); > + > + strlcpy(async_probe_drv_names, buf, ASYNC_DRV_NAMES_MAX_LEN - 1); > + return 0; > +} > +__setup("driver_async_probe=", save_async_options); > + > bool driver_allows_async_probing(struct device_driver *drv) > { > + if (unlikely(cmdline_requested_async_probing(drv->name))) > + return true; > + Instead of placing it here it might make more sense to place it down in the "default" case. This way we don't override a PROBE_FORCE_SYNCHRONOUS if that is the probe type value used by the driver. > switch (drv->probe_type) { > case PROBE_PREFER_ASYNCHRONOUS: > return true; > -- > 2.7.4 >
