[RFC PATCH v3 0/5] HID: spi-hid: add quad-SPI support for Romulus13

[Jizhou Tong]

Hi Jingyuan, Dale,

This RFC adds quad-SPI support for the Surface Laptop 7 13.8-inch
(Romulus13) touchpad to Jingyuan's v7 driver [1], on top of the two reset
GPIO error fixes sent separately.

It adds aligned transport buffers, spi-mem 1-4-4 transfers, bounded input
fragment assembly, and Romulus match data. After a device reset, Romulus
recreates the HID device so iptsd reapplies the touchpad mode without
restarting iptsd. Single-lane devices retain their ordinary SPI transfers.

Following Conor's review [2], the compatible and quad-width constraints
now extend hid-over-spi.yaml. There is no separate Romulus binding or
redundant declaration of the globally allowed pinctrl properties.

The final driver source matches the SPI-HID source in my tested downstream
SL7 kernel. Touchpad input and suspend/resume work there with the downstream
Qualcomm GENI/GPI QSPI controller and board changes. Those dependencies
are being prepared separately from this HID transport RFC.

The core, ACPI and OF modules build with W=1 against the prepared SL7
kernel build. Software tests cover header and fragment bounds, DMA buffer
alignment and allocation failures, SPI/QSPI transfer phases, reset errors,
and resume/re-probe ordering. The common binding passes schema validation
and compiled positive/negative examples, including both IRQ spellings.

Changes since v2:
- Rebase onto v7's compatible data, descriptor and PM handling.
- Drop the readiness/error-counter ABI; keep v7's removal of counters.
- Extend the common binding and remove redundant pinctrl declarations.
- Keep quad-only output framing checks out of the single-lane path.

[1] https://lore.kernel.org/all/20261024-send-upstream-v7-0-abad13174b43@xxxxxxxxxxxx/
[2] https://lore.kernel.org/all/20261028-punctured-flagpole-c7ec4cfc4609@spud/

Jizhou Tong (5):
  HID: spi-hid: isolate DMA transfers from protocol buffers
  HID: spi-hid: add spi-mem quad-SPI transfers
  HID: spi-hid: assemble bounded fragmented input reports
  dt-bindings: input: hid-over-spi: add the Surface Laptop 7 touchpad
  HID: spi-hid: support the Romulus13 QSPI touchpad

 .../bindings/input/hid-over-spi.yaml          |  40 ++++
 drivers/hid/spi-hid/Kconfig                   |   2 +-
 drivers/hid/spi-hid/spi-hid-acpi.c            |  26 +--
 drivers/hid/spi-hid/spi-hid-core.c            | 183 +++++++++++++++---
 drivers/hid/spi-hid/spi-hid-core.h            |   8 +
 drivers/hid/spi-hid/spi-hid-of.c              |  44 +++--
 drivers/hid/spi-hid/spi-hid.h                 |   8 +-
 7 files changed, 249 insertions(+), 62 deletions(-)


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