linux-kernel - Re: [PATCH] HID: multitouch: make mt_set

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Message-ID: <Zx_gRK9siGDtJ3PN@google.com>
Date: Mon, 28 Oct 2024 12:04:36 -0700
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: Benjamin Tissoires <bentiss@...nel.org>
Cc: Jiri Kosina <jikos@...nel.org>, linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] HID: multitouch: make mt_set_mode() less cryptic

On Mon, Oct 28, 2024 at 04:47:55PM +0100, Benjamin Tissoires wrote:
> On Oct 25 2024, Dmitry Torokhov wrote:
> > mt_set_mode() accepts 2 boolean switches indicating whether the device
> > (if it follows Windows Precision Touchpad specification) should report
> > hardware buttons and/or surface contacts. For a casual reader it is
> > completely not clear, as they look at the call site, which exact mode
> > is being requested.
> > 
> > Define report_mode enum and change mt_set_mode() to accept is as
> > an argument instead. This allows to write:
> > 
> > 	mt_set_modes(hdev, HID_LATENCY_NORMAL, TOUCHPAD_REPORT_ALL);
> > 
> > or
> > 
> > 	mt_set_modes(hdev, HID_LATENCY_HIGH, TOUCHPAD_REPORT_BUTTONS);
> > 
> > which makes intent much more clear.
> > 
> > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
> > ---
> >  drivers/hid/hid-multitouch.c | 29 +++++++++++++++++------------
> >  1 file changed, 17 insertions(+), 12 deletions(-)
> > 
> > diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
> > index 99812c0f830b..e4bb2fb5596d 100644
> > --- a/drivers/hid/hid-multitouch.c
> > +++ b/drivers/hid/hid-multitouch.c
> > @@ -83,6 +83,13 @@ enum latency_mode {
> >  	HID_LATENCY_HIGH = 1,
> >  };
> >  
> > +enum report_mode {
> > +	TOUCHPAD_REPORT_NONE = 0,
> > +	TOUCHPAD_REPORT_BUTTONS = 1,
> > +	TOUCHPAD_REPORT_CONTACTS = 2,
> 
> Maybe to be more obvious, BIT(0) and BIT(1) for the 2 values above?
> 
> I'm just concerned that someone adds "3" if we ever need to add a new
> value.

Right, I'll change it.

> 
> > +	TOUCHPAD_REPORT_ALL = TOUCHPAD_REPORT_BUTTONS | TOUCHPAD_REPORT_CONTACTS,
> > +};
> > +
> >  #define MT_IO_FLAGS_RUNNING		0
> >  #define MT_IO_FLAGS_ACTIVE_SLOTS	1
> >  #define MT_IO_FLAGS_PENDING_SLOTS	2
> > @@ -1486,8 +1493,7 @@ static bool mt_need_to_apply_feature(struct hid_device *hdev,
> >  				     struct hid_field *field,
> >  				     struct hid_usage *usage,
> >  				     enum latency_mode latency,
> > -				     bool surface_switch,
> > -				     bool button_switch,
> > +				     enum report_mode report_mode,
> >  				     bool *inputmode_found)
> >  {
> >  	struct mt_device *td = hid_get_drvdata(hdev);
> > @@ -1542,11 +1548,11 @@ static bool mt_need_to_apply_feature(struct hid_device *hdev,
> >  		return true;
> >  
> >  	case HID_DG_SURFACESWITCH:
> > -		field->value[index] = surface_switch;
> > +		field->value[index] = report_mode & TOUCHPAD_REPORT_CONTACTS;
> 
> Just to be on the safe side:
> !!(report_mode & TOUCHPAD_REPORT_CONTACTS);

Oh, yes, that makes sense. I'll send an updated patch in a minute.

Thanks.

-- 
Dmitry