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

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Message-ID: <0559f42a6a1ff5813884a4a78de23f54@trvn.ru>
Date: Thu, 03 Oct 2024 18:08:57 +0500
From: Nikita Travkin <nikita@...n.ru>
To: Dmitry Torokhov <dmitry.torokhov@...il.com>
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

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?

Thank you for looking at this!
Nikita

> 
> Thanks.