linux-kernel - Re: [PATCH v2 2/2] HID: Make elan touch controllers power on after panel is enabled

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Message-ID: <CAEXTbpcTJVCqR-NAfddd2H9oLUitcUi3XnX1GQf7hA06-Vx9UQ@mail.gmail.com>
Date: Mon, 18 Aug 2025 19:49:12 +0800
From: Pin-yen Lin <treapking@...omium.org>
To: Doug Anderson <dianders@...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>, dri-devel@...ts.freedesktop.org, 
	linux-kernel@...r.kernel.org, linux-input@...r.kernel.org, 
	Chen-Yu Tsai <wenst@...omium.org>
Subject: Re: [PATCH v2 2/2] HID: Make elan touch controllers power on after
 panel is enabled

Hi Doug,

On Fri, Aug 15, 2025 at 8:27 AM Doug Anderson <dianders@...omium.org> wrote:
>
> Hi,
>
> On Wed, Aug 13, 2025 at 5:51 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.
> >
> > Signed-off-by: Pin-yen Lin <treapking@...omium.org>
> >
> > ---
> >
> > 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(-)
>
> This seems reasonable to me.
>
> Reviewed-by: Douglas Anderson <dianders@...omium.org>
>
> Given that this affects devices that we already had support for
> (you're changing the behavior of two touchscreens), should it have a
> Fixes tag?

I'll add Fixes tags in the next version.
>
> We'll also need to figure out a process for landing the two patches. I
> can easily land the first one in drm-misc-next, but then it'll be a
> while before the i2c-hid one can land. Is it OK to wait?

I'm okay with waiting for the next release for i2c-hid patch to land.
Or should will ask the HID maintainers to ack this patch?
>
>
> -Doug

Regards,
Pin-yen