On Fri, Dec 11, 2020 at 10:03 AM Marc Zyngier <maz@xxxxxxxxxx> wrote: > > On 2020-12-11 17:51, Saravana Kannan wrote: > > On Fri, Dec 11, 2020 at 8:34 AM Robin Murphy <robin.murphy@xxxxxxx> > > wrote: > >> > >> On 2020-12-11 14:11, Qian Cai wrote: > >> > On Fri, 2020-11-20 at 18:02 -0800, Saravana Kannan wrote: > >> >> The current implementation of fw_devlink is very inefficient because it > >> >> tries to get away without creating fwnode links in the name of saving > >> >> memory usage. Past attempts to optimize runtime at the cost of memory > >> >> usage were blocked with request for data showing that the optimization > >> >> made significant improvement for real world scenarios. > >> >> > >> >> We have those scenarios now. There have been several reports of boot > >> >> time increase in the order of seconds in this thread [1]. Several OEMs > >> >> and SoC manufacturers have also privately reported significant > >> >> (350-400ms) increase in boot time due to all the parsing done by > >> >> fw_devlink. > >> >> > >> >> So this patch uses all the setup done by the previous patches in this > >> >> series to refactor fw_devlink to be more efficient. Most of the code has > >> >> been moved out of firmware specific (DT mostly) code into driver core. > >> >> > >> >> This brings the following benefits: > >> >> - Instead of parsing the device tree multiple times during bootup, > >> >> fw_devlink parses each fwnode node/property only once and creates > >> >> fwnode links. The rest of the fw_devlink code then just looks at these > >> >> fwnode links to do rest of the work. > >> >> > >> >> - Makes it much easier to debug probe issue due to fw_devlink in the > >> >> future. fw_devlink=on blocks the probing of devices if they depend on > >> >> a device that hasn't been added yet. With this refactor, it'll be very > >> >> easy to tell what that device is because we now have a reference to > >> >> the fwnode of the device. > >> >> > >> >> - Much easier to add fw_devlink support to ACPI and other firmware > >> >> types. A refactor to move the common bits from DT specific code to > >> >> driver core was in my TODO list as a prerequisite to adding ACPI > >> >> support to fw_devlink. This series gets that done. > >> >> > >> >> [1] - https://lore.kernel.org/linux-omap/ea02f57e-871d-cd16-4418-c1da4bbc4696@xxxxxx/ > >> >> Signed-off-by: Saravana Kannan <saravanak@xxxxxxxxxx> > >> >> Tested-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> > >> >> Tested-by: Grygorii Strashko <grygorii.strashko@xxxxxx> > >> > > >> > Reverting this commit and its dependency: > >> > > >> > 2d09e6eb4a6f driver core: Delete pointless parameter in fwnode_operations.add_links > >> > > >> > from today's linux-next fixed a boot crash on an arm64 Thunder X2 server. > >> > >> Since the call stack implicates the platform-device-wrangling we do in > >> IORT code I took a quick look; AFAICS my guess would be it's blowing > >> up > >> trying to walk a zeroed list head since "driver core: Add > >> fwnode_init()" > >> missed acpi_alloc_fwnode_static(). > > > > Thanks Robin. I'm pretty sure this is the reason. I thought I fixed > > all ACPI cases, but clearly I missed this one. I'll send out a patch > > for this today. If you think there are any other places I missed > > please let me know. I'll try some git grep foo to see if I missed any > > other instances of fwnode ops being set. > > Yup, that fixed it here (QDF2400). > > Thanks, > > M. > > diff --git a/include/linux/acpi.h b/include/linux/acpi.h > index 39263c6b52e1..2630c2e953f7 100644 > --- a/include/linux/acpi.h > +++ b/include/linux/acpi.h > @@ -55,7 +55,7 @@ static inline struct fwnode_handle > *acpi_alloc_fwnode_static(void) > if (!fwnode) > return NULL; > > - fwnode->ops = &acpi_static_fwnode_ops; > + fwnode_init(fwnode, &acpi_static_fwnode_ops); > > return fwnode; > } > Lol, my only contribution to the patch will be the commit text. I'll send them with reported-by, suggested-by and tested-by if no one less beats me to it. -Saravana
