linux-kernel - Re: [PATCH v3 2/2] HID: Make elan touch controllers power on after panel is enabled

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Message-ID: <CAD=FV=WCfFWHAh=XxA_jZpMsS_L0U_k=_g_oj36Nd=4winZ24g@mail.gmail.com>
Date: Mon, 18 Aug 2025 13:14:08 -0700
From: Doug Anderson <dianders@...omium.org>
To: Pin-yen Lin <treapking@...omium.org>
Cc: Neil Armstrong <neil.armstrong@...aro.org>, Jessica Zhang <quic_jesszhan@...cinc.com>, 
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>, 
	Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
	Jiri Kosina <jikos@...nel.org>, Benjamin Tissoires <bentiss@...nel.org>, linux-kernel@...r.kernel.org, 
	linux-input@...r.kernel.org, Chen-Yu Tsai <wenst@...omium.org>, 
	dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH v3 2/2] HID: Make elan touch controllers power on after
 panel is enabled

Hi,

On Mon, Aug 18, 2025 at 4:50 AM Pin-yen Lin <treapking@...omium.org> 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@...omium.org>
> Signed-off-by: Pin-yen Lin <treapking@...omium.org>
>
> ---
>
> 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/