linux-kernel - Re: [PATCH] Input: stmpe-keypad

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Date:   Fri, 9 Mar 2018 21:32:21 -0600
From:   "Gustavo A. R. Silva" <garsilva@...eddedor.com>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:     linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Input: stmpe-keypad - remove VLA usage

Hi Dmitry,

On 03/09/2018 05:32 PM, Dmitry Torokhov wrote:
> On Fri, Mar 09, 2018 at 04:42:08PM -0600, Gustavo A. R. Silva wrote:
>> In preparation to enabling -Wvla, remove VLA and replace it
>> with a fixed-length array instead.
>>
>> Fixed as part of the directive to remove all VLAs from
>> the kernel: https://lkml.org/lkml/2018/3/7/621
>>
>> Signed-off-by: Gustavo A. R. Silva <garsilva@...eddedor.com>
>> ---
>>   drivers/input/keyboard/stmpe-keypad.c | 10 ++++++----
>>   1 file changed, 6 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/input/keyboard/stmpe-keypad.c b/drivers/input/keyboard/stmpe-keypad.c
>> index 8c6c0b9..cfa1dbe 100644
>> --- a/drivers/input/keyboard/stmpe-keypad.c
>> +++ b/drivers/input/keyboard/stmpe-keypad.c
>> @@ -48,6 +48,8 @@
>>   #define STMPE_KEYPAD_KEYMAP_MAX_SIZE \
>>   	(STMPE_KEYPAD_MAX_ROWS * STMPE_KEYPAD_MAX_COLS)
>>   
>> +#define MAX_NUM_DATA			5
>> +
>>   /**
>>    * struct stmpe_keypad_variant - model-specific attributes
>>    * @auto_increment: whether the KPC_DATA_BYTE register address
>> @@ -74,7 +76,7 @@ struct stmpe_keypad_variant {
>>   static const struct stmpe_keypad_variant stmpe_keypad_variants[] = {
>>   	[STMPE1601] = {
>>   		.auto_increment		= true,
>> -		.num_data		= 5,
>> +		.num_data		= MAX_NUM_DATA,
>>   		.num_normal_data	= 3,
>>   		.max_cols		= 8,
>>   		.max_rows		= 8,
>> @@ -84,7 +86,7 @@ static const struct stmpe_keypad_variant stmpe_keypad_variants[] = {
>>   	[STMPE2401] = {
>>   		.auto_increment		= false,
>>   		.set_pullup		= true,
>> -		.num_data		= 3,
>> +		.num_data		= MAX_NUM_DATA - 2,
> 
> Logically MAX_NUM_DATA - 2 does not mean anything, it is simply a way
> for you to get to 3, so I'd rather we did not do that.
> 

Yeah. I agree.

> Can we do
> 
> #define STMPE1601_NUM_DATA	5
> #define STMPE2401_NUM_DATA	3
> #define STMPE2403_NUM_DATA	5
> #define MAX_NUM_DATA		max3(STMPE1601_NUM_DATA, \
> 				     STMPE2401_NUM_DATA, \
> 				     STMPE2403_NUM_DATA)
> 
> 
> or simply
> 
> /* Make sure it covers all cases above */
> #define MAX_NUM_DATA		5

This one works just fine.

I'll send v2 of this patch shortly.

Thanks for the feedback.
I appreciate it.
--
Gustavo

> 
>>   		.num_normal_data	= 2,
>>   		.max_cols		= 8,
>>   		.max_rows		= 12,
>> @@ -94,7 +96,7 @@ static const struct stmpe_keypad_variant stmpe_keypad_variants[] = {
>>   	[STMPE2403] = {
>>   		.auto_increment		= true,
>>   		.set_pullup		= true,
>> -		.num_data		= 5,
>> +		.num_data		= MAX_NUM_DATA,
>>   		.num_normal_data	= 3,
>>   		.max_cols		= 8,
>>   		.max_rows		= 12,
>> @@ -156,7 +158,7 @@ static irqreturn_t stmpe_keypad_irq(int irq, void *dev)
>>   	struct stmpe_keypad *keypad = dev;
>>   	struct input_dev *input = keypad->input;
>>   	const struct stmpe_keypad_variant *variant = keypad->variant;
>> -	u8 fifo[variant->num_data];
>> +	u8 fifo[MAX_NUM_DATA];
>>   	int ret;
>>   	int i;
>>   
>> -- 
>> 2.7.4
>>
> 
> Thanks.
>