Hi,

On Mon, Aug 18, 2025 at 4:50 AM Pin-yen Lin [off-list ref] wrote:

Introduce a new HID quirk to indicate that this device has to be enabled
after the panel's backlight is enabled, and update the driver data for
the elan devices to enable this quirk. This cannot be a I2C HID quirk
because the kernel needs to acknowledge this before powering up the
device and read the VID/PID. When this quirk is enabled, register
.panel_enabled()/.panel_disabling() instead for the panel follower.

Also rename the *panel_prepare* functions into *panel_follower* because
they could be called in other situations now.

Fixes: bd3cba00dcc63 ("HID: i2c-hid: elan: Add support for Elan eKTH6915 i2c-hid touchscreens")
Fixes: d06651bebf99e ("HID: i2c-hid: elan: Add elan-ekth6a12nay timing")

Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Pin-yen Lin <redacted>

---

Changes in v3:
- Collect review tag
- Add fixes tags

Changes in v2:
- Rename *panel_prepare* functions to *panel_follower*
- Replace after_panel_enabled flag with enabled/disabling callbacks

 drivers/hid/i2c-hid/i2c-hid-core.c    | 46 ++++++++++++++++-----------
 drivers/hid/i2c-hid/i2c-hid-of-elan.c | 11 ++++++-
 include/linux/hid.h                   |  2 ++
 3 files changed, 40 insertions(+), 19 deletions(-)

Re-iterating my response from v2 [1] so it's still seen even if people
only look at the latest version. :-) If HID folks don't mind us
landing this through drm-misc, feel free to Ack this patch. If HID
folks would rather not land through drm-misc, the default plan would
be to just wait until patch #1 makes its way to mainline before
landing patch #2.

Thanks!

[1] https://lore.kernel.org/r/CAD=FV=UV8_XGmxC=7Z18PEnj6wKz+yZQuV_4h+LJh_MNCqszvg@mail.gmail.com/ (local)