Input: iqs269a - Use common error handling code in iqs269_parse_chan()

From: Markus Elfring <elfring@users.sourceforge.net>
Date: Sat, 2 Mar 2024 09:15:20 +0100

Add a jump target so that a bit of exception handling can be better reused
at the end of this function implementation.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
---
 drivers/input/misc/iqs269a.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

--
2.44.0

Hi Markus,

On Sat, Mar 02, 2024 at 09:24:53AM +0100, Markus Elfring wrote:
> From: Markus Elfring <elfring@users.sourceforge.net>
> Date: Sat, 2 Mar 2024 09:15:20 +0100
> 
> Add a jump target so that a bit of exception handling can be better reused
> at the end of this function implementation.

No, I do not think this is needed. However if you can introduce a fwnode
cleanup/free function (see include/linux/cleanup.h) maybe it would be
more useful and we could apply it to various drivers.

Thanks.

Hi Markus,

On Mon, Mar 04, 2024 at 10:55:11AM +0100, Markus Elfring wrote:
> From: Markus Elfring <elfring@users.sourceforge.net>
> Date: Mon, 4 Mar 2024 10:30:52 +0100
> 
> Scope-based resource management became supported also for this software
> area by contributions of Jonathan Cameron on 2024-02-17.
> 
> device property: Add cleanup.h based fwnode_handle_put() scope based cleanup.
> https://lore.kernel.org/r/20240217164249.921878-3-jic23@kernel.org
> 
> 
> * Thus use the attribute “__free(fwnode_handle)”.
> 
> * Reduce the scope for the local variable “ev_node” into a for loop.
> 
> Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
> ---
> 
> v2:
> An other cleanup technique was applied as requested by Dmitry Torokhov.
> 
> 
>  drivers/input/misc/iqs269a.c | 73 ++++++++++++++++++------------------
>  1 file changed, 37 insertions(+), 36 deletions(-)
> 
> diff --git a/drivers/input/misc/iqs269a.c b/drivers/input/misc/iqs269a.c
> index cd14ff9f57cf..9caee936927b 100644
> --- a/drivers/input/misc/iqs269a.c
> +++ b/drivers/input/misc/iqs269a.c
> @@ -557,7 +557,6 @@ static int iqs269_parse_chan(struct iqs269_private *iqs269,
>  			     const struct fwnode_handle *ch_node)
>  {
>  	struct i2c_client *client = iqs269->client;
> -	struct fwnode_handle *ev_node;
>  	struct iqs269_ch_reg *ch_reg;
>  	u16 engine_a, engine_b;
>  	unsigned int reg, val;
> @@ -734,47 +733,49 @@ static int iqs269_parse_chan(struct iqs269_private *iqs269,
>  	}
> 
>  	for (i = 0; i < ARRAY_SIZE(iqs269_events); i++) {
> -		ev_node = fwnode_get_named_child_node(ch_node,
> -						      iqs269_events[i].name);
> -		if (!ev_node)
> -			continue;
> -
> -		if (!fwnode_property_read_u32(ev_node, "azoteq,thresh", &val)) {
> -			if (val > IQS269_CHx_THRESH_MAX) {
> -				dev_err(&client->dev,
> -					"Invalid channel %u threshold: %u\n",
> -					reg, val);
> -				fwnode_handle_put(ev_node);
> -				return -EINVAL;
> +		{
> +			struct fwnode_handle *ev_node __free(fwnode_handle)
> +						      = fwnode_get_named_child_node(ch_node,
> +										    iqs269_events[i].name);
> +
> +			if (!ev_node)
> +				continue;
> +
> +			if (!fwnode_property_read_u32(ev_node, "azoteq,thresh", &val)) {
> +				if (val > IQS269_CHx_THRESH_MAX) {
> +					dev_err(&client->dev,
> +						"Invalid channel %u threshold: %u\n",
> +						reg, val);
> +					return -EINVAL;
> +				}
> +
> +				ch_reg->thresh[iqs269_events[i].th_offs] = val;

I may just be a curmudgeon, but this is another NAK for me. The dummy
curly braces and extra indentation make the code difficult to understand,
and this simply does not seem like a natural way to write a driver. Just
to remove 2-3 calls to fwnode_handle_put()?

>  			}
> 
> -			ch_reg->thresh[iqs269_events[i].th_offs] = val;
> -		}
> -
> -		if (!fwnode_property_read_u32(ev_node, "azoteq,hyst", &val)) {
> -			u8 *hyst = &ch_reg->hyst;
> -
> -			if (val > IQS269_CHx_HYST_MAX) {
> -				dev_err(&client->dev,
> -					"Invalid channel %u hysteresis: %u\n",
> -					reg, val);
> -				fwnode_handle_put(ev_node);
> -				return -EINVAL;
> +			if (!fwnode_property_read_u32(ev_node, "azoteq,hyst", &val)) {
> +				u8 *hyst = &ch_reg->hyst;
> +
> +				if (val > IQS269_CHx_HYST_MAX) {
> +					dev_err(&client->dev,
> +						"Invalid channel %u hysteresis: %u\n",
> +						reg, val);
> +					return -EINVAL;
> +				}
> +
> +				if (i == IQS269_EVENT_DEEP_DN ||
> +				    i == IQS269_EVENT_DEEP_UP) {
> +					*hyst &= ~IQS269_CHx_HYST_DEEP_MASK;
> +					*hyst |= (val << IQS269_CHx_HYST_DEEP_SHIFT);
> +				} else if (i == IQS269_EVENT_TOUCH_DN ||
> +					   i == IQS269_EVENT_TOUCH_UP) {
> +					*hyst &= ~IQS269_CHx_HYST_TOUCH_MASK;
> +					*hyst |= val;
> +				}
>  			}
> 
> -			if (i == IQS269_EVENT_DEEP_DN ||
> -			    i == IQS269_EVENT_DEEP_UP) {
> -				*hyst &= ~IQS269_CHx_HYST_DEEP_MASK;
> -				*hyst |= (val << IQS269_CHx_HYST_DEEP_SHIFT);
> -			} else if (i == IQS269_EVENT_TOUCH_DN ||
> -				   i == IQS269_EVENT_TOUCH_UP) {
> -				*hyst &= ~IQS269_CHx_HYST_TOUCH_MASK;
> -				*hyst |= val;
> -			}
> +			error = fwnode_property_read_u32(ev_node, "linux,code", &val);
>  		}
> 
> -		error = fwnode_property_read_u32(ev_node, "linux,code", &val);
> -		fwnode_handle_put(ev_node);
>  		if (error == -EINVAL) {
>  			continue;
>  		} else if (error) {
> --
> 2.44.0
> 

Kind regards,
Jeff LaBundy

> The extra curly braces are absolutely not needed. The for loop's body
> already defines scope, __cleanup()s should be called at the end of the body.

I present an other development opinion here.
I got the impression that the required scope should be smaller for
the adjusted local variable “ev_node” (according to the previous function implementation).

Otherwise:
How do you think about to move any source code part from the loop
into a separate function?

Regards,
Markus