Re: [RFC v9 1/1] leds: asus-aura-scsi: Add ASUS Aura RGB LED driver for ROG NVMe enclosures

[Lee Jones]

On Fri, 25 Sep 2026, Lee Jones wrote:

> --- checkpatch.pl: clean (0 issues) ---
> 
> On Fri, 25 Sep 2026, Liang Haowen wrote:
> 
> > ASUS ROG external NVMe enclosures (ROG STRIX Arion, USB 0b05:1932) are
> > plain USB mass-storage devices with no HID interface: the Aura LEDs
> > hang off an ENE controller driven by vendor SCSI commands on the same
> > LUN as the disk. The enclosure has 4 independently addressable LEDs,
> > verified on hardware.
> >
> > Register a scsi_device_handler matched by INQUIRY (vendor "ROG",
> > model "ESD-S1C"); it does not claim the sdev (sd keeps owning the
> > disk) and exposes each LED as a multicolor LED class device,
> > /sys/class/leds/asus-arion-0-0-0-0::led-0 through led-3. The
> > H:C:T:L part of the sdev name keeps the names unique when more than
> > one enclosure is connected, with its colons flattened to dashes. The
> > color section stays empty, since multicolor LEDs enumerate their
> > palette via multi_intensity, and the four identical zones use the
> > function name with a "-N" ordinal, as the naming section in
> > Documentation/leds/leds-class.rst asks for.
> >
> > Protocol: a 16-byte vendor CDB (opcode 0xec, 'A' 'S' signature,
> > BE16 register index, argument count in byte 13), modelled by
> > struct ene_cdb. MODE 0x8021 (Static) must be written first in every
> > sequence or the device ignores it; colours go to 0x8160 + 3 * led
> > and 0x8100 + 3 * led (3 bytes, wire order R, B, G; both tables are
> > written because firmware revisions pull from one or the other);
> > APPLY 0x80a0 takes 0x01 to apply; the controller also accepts 0xaa
> > to save the state to its flash, which this driver never sends: the
> > LED class interface is runtime state and does not promise persistence
> > across power cycles, and a save on every update would wear the
> > controller flash. The colour reverts to the stored default on power
> > cycle, like any other runtime-only LED.
> >
> > The CDB cannot go through scsi_execute_cmd(): it sizes the command
> > via scsi_command_size(opcode), which maps vendor opcode 0xec to
> > 10 bytes, so byte 13 is dropped and the device silently ignores the
> > write (GOOD status, no error). scsi_execute_cmd() also offers no way
> > to override the derived length. The request is therefore built with
> > scsi_alloc_request(), which initializes the scsi_cmnd parts a
> > passthrough needs, with cmd_len set to the CDB size, mirroring what
> > SG_IO does from userspace. A 5 s timeout and a single retry-less
> > quiet submission cover the register writes.
> >
> > The write payload is copied into a per-device buffer before it is
> > mapped with blk_rq_map_kern(), so no stack memory is ever mapped for
> > DMA (VMAP_STACK).
> >
> > brightness_set only caches the colour and marks the LED pending
> > under a spinlock; led_mc_calc_color_components() runs under that
> > lock too, because it writes the shared subled_info array and
> > trigger events call led_set_brightness() without the led_access lock
> > that serializes sysfs stores. A single work item per enclosure then
> > snapshots the pending LEDs and runs one ENE sequence for all of
> > them. Funneling every update through one work item keeps the
> > sequences from interleaving between concurrent LED updates and
> > batches multi-LED updates into a single APPLY. A re-queued run
> > with nothing pending returns before touching the device, so it
> > cannot wear the flash with a pointless SAVE, and the lock keeps a
> > colour write from being reordered after its pending flag on weakly
> > ordered architectures.
> >
> > This is the monolithic out-of-tree version as verified on hardware;
> > the Kconfig/Makefile/MAINTAINERS wiring lands with the agreed split
> > into a SCSI transport helper and a shared ASUS Aura LED interface.
> >
> > Signed-off-by: Liang Haowen <nbg2974@xxxxxxxxx>
> > ---
> >  drivers/leds/rgb/leds-asus-aura-scsi.c | 404 +++++++++++++++++++++++++
> >  1 file changed, 404 insertions(+)
> >  create mode 100644 drivers/leds/rgb/leds-asus-aura-scsi.c
> 
> A driver source file without 'Kconfig' or 'Makefile' integration is dead code in
> the tree.  Either wire it up now or hold off on submitting until the rest of the
> pieces are ready.

Also:

Thank you for your contribution! Sashiko AI review found 3 potential issue(s) to consider:
- [Low] leds: asus-aura-scsi: undefined function kzalloc_obj() causes build failure       
- [Low] leds: asus-aura-scsi: blk_rq_map_kern() missing required request_queue argument   
- [Low] leds: asus-aura-scsi: strscpy() called with missing size argument

Was this even tested?

-- 
Lee Jones