linux-kernel - Re: [PATCH] Input: zinitix - Don't fail if linux,keycodes prop is absent

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Message-ID: <Zv6X46ks3xD0p4pn@google.com>
Date: Thu, 3 Oct 2024 06:10:59 -0700
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: Nikita Travkin <nikita@...n.ru>
Cc: Linus Walleij <linus.walleij@...aro.org>, linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org, Jakob Hauser <jahau@...ketmail.com>
Subject: Re: [PATCH] Input: zinitix - Don't fail if linux,keycodes prop is
 absent

On Thu, Oct 03, 2024 at 06:08:57PM +0500, Nikita Travkin wrote:
> Dmitry Torokhov писал(а) 03.10.2024 16:43:
> > Hi Nikita,
> > 
> > On Wed, Oct 02, 2024 at 06:01:48PM +0500, Nikita Travkin wrote:
> >> When initially adding the touchkey support, a mistake was made in the
> >> property parsing code. The possible negative errno from
> >> device_property_count_u32() was never checked, which was an oversight
> >> left from converting to it from the of_property as part of the review
> >> fixes.
> >> 
> >> Re-add the correct handling of the absent property, in which case zero
> >> touchkeys should be assumed, which would disable the feature.
> >> 
> >> Reported-by: Jakob Hauser <jahau@...ketmail.com>
> >> Tested-by: Jakob Hauser <jahau@...ketmail.com>
> >> Fixes: 075d9b22c8fe ("Input: zinitix - add touchkey support")
> >> Signed-off-by: Nikita Travkin <nikita@...n.ru>
> >> ---
> >>  drivers/input/touchscreen/zinitix.c | 33 ++++++++++++++++++++++-----------
> >>  1 file changed, 22 insertions(+), 11 deletions(-)
> >> 
> >> diff --git a/drivers/input/touchscreen/zinitix.c b/drivers/input/touchscreen/zinitix.c
> >> index 52b3950460e2..1f726653940c 100644
> >> --- a/drivers/input/touchscreen/zinitix.c
> >> +++ b/drivers/input/touchscreen/zinitix.c
> >> @@ -645,19 +645,30 @@ static int zinitix_ts_probe(struct i2c_client *client)
> >>  		return error;
> >>  	}
> >>  
> >> -	bt541->num_keycodes = device_property_count_u32(&client->dev, "linux,keycodes");
> >> -	if (bt541->num_keycodes > ARRAY_SIZE(bt541->keycodes)) {
> >> -		dev_err(&client->dev, "too many keys defined (%d)\n", bt541->num_keycodes);
> >> -		return -EINVAL;
> >> +	error = device_property_count_u32(&client->dev, "linux,keycodes");
> >> +	if (error == -EINVAL || error == -ENODATA) {
> >> +		bt541->num_keycodes = 0;
> >> +	} else if (error < 0) {
> >> +		dev_err(&client->dev, "Failed to count \"linux,keycodes\" property: %d\n", error);
> >> +		return error;
> >> +	} else {
> >> +		bt541->num_keycodes = error;
> >>  	}
> >>  
> >> -	error = device_property_read_u32_array(&client->dev, "linux,keycodes",
> >> -					       bt541->keycodes,
> >> -					       bt541->num_keycodes);
> >> -	if (error) {
> >> -		dev_err(&client->dev,
> >> -			"Unable to parse \"linux,keycodes\" property: %d\n", error);
> >> -		return error;
> >> +	if (bt541->num_keycodes > 0) {
> > 
> > I think this check is not needed and "if" can be folded into "else"
> > above. But anyways, do you mind if I rewrite it as follows:
> > 
> > 	...
> > 
> > 	n_keycodes = device_property_count_u32(&client->dev, "linux,keycodes");
> > 	if (n_keycodes < 0) {
> > 		error = n_keycodes;
> > 		if (error != -EINVAL && error != -ENODATA) {
> > 			dev_err(&client->dev,
> > 				"Failed to count \"linux,keycodes\" property: %d\n",
> > 				error);
> > 			return error;
> > 		}
> > 	} else if (n_keycodes > 0) {
> > 		if (n_keycodes > ARRAY_SIZE(bt541->keycodes)) {
> > 			dev_err(&client->dev,
> > 				"too many keys defined (%d)\n", n_keycodes);
> > 			return -EINVAL;
> > 		}
> > 
> > 		error = device_property_read_u32_array(&client->dev,
> > 						       "linux,keycodes",
> > 						       bt541->keycodes,
> > 						       n_keycodes);
> > 		if (error) {
> > 			dev_err(&client->dev,
> > 				"Unable to parse \"linux,keycodes\" property: %d\n",
> > 				error);
> > 			return error;
> > 		}
> > 
> > 		bt541->num_keycodes = n_keycodes;
> > 	}
> > 
> > 
> > Or maybe to avoid checking for specific error codes we should do:
> > 
> > 	if (device_property_present(&client->dev, "linux,keycodes")) {
> > 		bt541->num_keycodes = device_property_count_u32(&client->dev,
> > 								"linux,keycodes");
> > 		if (bt541->num_keycodes < 0) {
> > 			error = bt541->num_keycodes;
> > 			dev_err(&client->dev, ...);
> > 			return error;
> > 		}
> > 
> > 		...
> > 	}
> > 
> 
> Oh, yeah, I didn't think of that but explicitly checking the presence
> makes the code easier to read. I think both options are fine but I'd
> prefer the (imo) easier to read second one. Should I submit a v2 or
> you're planning to fast-track it?

Please submit v2 since you have the hardware to do a quick test.

Thanks.

-- 
Dmitry