[PATCH v7 0/2] firmware: arm_scmi: fix module auto-loading

[Hans de Goede]

Hi All,

Here is v7 of the patch series fixing arm_scmi module autoloading this
combines:

1. Patch 1/2 from Bjorn to add support for scmi bus modaliases to modpost:
https://lore.kernel.org/all/20260618-scmi-modalias-v2-1-8c7547c1be21@xxxxxxxxxxxxxxxx/

2. A new patch 2/2 to always create devices for standard protocols,
replacing Cristian's patch to pre-register the standard protocol device-ids
from v4.

1. is not enough by itself because driver module auto-loading requires
the devices to already be created for udev to get the necessary uevents
based on which udev auto-loads modules.

But SCMI devices are only created after their { protocol, name } device-id
has been registered which is done from scmi_driver_register(), creating
a circular dependency.

2. breaks the circular dependency by always creating devices for standard
protocols without relying on the requested-devices list. This creates
devices before the module with the driver is loaded, after which module
auto loading works the same as it does on any other bus.

I've tested this on a T14s Snapdragon laptop with Fedora's kernel config
where scmi_cpufreq is a module. With this series scmi_cpufreq correctly
autoloads even if it is not included in the initramfs.

Changes in v7:
- Rebase on top of v7.3-rc3
- Drop:
  "firmware: arm_scmi: Fix scmi_protocol_table_register() error handling"
  "firmware: arm_scmi: Fix scmi_protocol_device_unrequest() race"
  these issues are already fixed through other patches in v7.3-rc3

Changes in v6:
- New: "firmware: arm_scmi: Fix scmi_protocol_device_unrequest() race"
- Add Fixes tags to the bug-fix patches
- Replace the if (!phead) return NULL; early exit with return scmi_dev;
  Since a standard protocol device may have been created at this point
  (from local Shashiko run)

Changes in v5:
- New patch: "firmware: arm_scmi: Fix scmi_protocol_table_register()
  error handling"
- Replace "Pre-register protocol, name tupples for standard protocol" with
  "Always create devices for standard protocols" pre-registering requires
  scmi_protocol_device_request() to allow duplicate device-ids, but then if
  the first driver of two with duplicate devce-ids gets unloaded device
  creation for the second driver will fail. Allowing duplicates causes all
  kinds of problems, so this new approach avoids this.
- Drop "Pre-register protocol, name tupples for IMX protocols" patch.
  Shashiko rightfully turns out this will cause problems if other vendors
  also use the same vendor protocol-id space values, e.g. 0x80, 0x81 are
  likely to also be used by other vendors.

Changes in v4:
- Drop unused driver_data member from struct scmi_device_id (Uwe)
- Drop device-id/scmi.h include from mod_devicetable.h (Uwe)
- Add device-id/scmi.h to devicetable-offsets.c and file2alias.c (Uwe)

Changes in v3:
- v3 is the first series combining Bjorn and Christian's work see above.

Regards,

Hans


Bjorn Andersson (1):
  module: add SCMI device table alias support

Hans de Goede (1):
  firmware: arm_scmi: Always create devices for standard protocols

 MAINTAINERS                       |  1 +
 drivers/firmware/arm_scmi/bus.c   | 71 +++++++++++++++++++++++++------
 include/linux/device-id/scmi.h    | 17 ++++++++
 include/linux/scmi_protocol.h     |  6 +--
 scripts/mod/devicetable-offsets.c |  5 +++
 scripts/mod/file2alias.c          | 12 ++++++
 6 files changed, 93 insertions(+), 19 deletions(-)
 create mode 100644 include/linux/device-id/scmi.h

-- 
2.55.0