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

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Message-ID: <CAD=FV=UV8_XGmxC=7Z18PEnj6wKz+yZQuV_4h+LJh_MNCqszvg@mail.gmail.com>
Date: Mon, 18 Aug 2025 08:45:48 -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>, 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,

On Mon, Aug 18, 2025 at 4:49 AM Pin-yen Lin <treapking@...omium.org> wrote:
>
> 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?

I'll also respond on the v3, but probably the easiest is just:

* I won't wait for a response for the HID maintainers before landing
patch #1 into drm-misc.

* If HID maintainers don't want to Ack the patch for landing through
drm-misc, we'll just pause landing of patch #2 until things percolate
to mainline.

-Doug