Messages in this thread | | | Subject | Re: [RFC PATCH v2] async: Add cmdline option to specify drivers to be async probed | From | Alexander Duyck <> | Date | Mon, 28 Jan 2019 08:31:11 -0800 |
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On Mon, 2019-01-28 at 09:20 +0800, Feng Tang wrote: > Asynchronous driver probing can help much on kernel 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 families of HWs, some of which > could use async probing 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 async patch 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, while async probing may make those controllers get different > index for each boot, which prevents those controller drivers to be > async probed. For platforms not using these spi/i2c slave devices, > they can use this cmdline option to benefit from the async probing. > > Suggested-by: Alexander Duyck <alexander.h.duyck@linux.intel.com> > Signed-off-by: Feng Tang <feng.tang@intel.com> > --- > drivers/base/dd.c | 23 +++++++++++++++++++++++ > 1 file changed, 23 insertions(+) > > diff --git a/drivers/base/dd.c b/drivers/base/dd.c > index 8ac10af..cfa704a 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 +678,27 @@ 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); > +} > + > +/* The format is like driver_async_probe=drv_name1,drv_name2,drv_name3 */ > +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); > + return 0; > +} > +__setup("driver_async_probe=", save_async_options); > + > bool driver_allows_async_probing(struct device_driver *drv) > { > + if (cmdline_requested_async_probing(drv->name)) > + return true; > +
This piece still should be moved. Ideally it should be down in the "default" case area we use to determine if the module parameter async_probe was used or not. Where you currently have this will overrride the driver behavior if it absolutely cannot use an asynchronous probe.
> switch (drv->probe_type) { > case PROBE_PREFER_ASYNCHRONOUS: > return true;
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