linux-kernel - Re: [PATCH v4 8/8] gpiolib: notify user-space about in-kernel line state changes

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Message-ID: <20241017125349.GB221864@rigel>
Date: Thu, 17 Oct 2024 20:53:49 +0800
From: Kent Gibson <warthog618@...il.com>
To: Bartosz Golaszewski <brgl@...ev.pl>
Cc: Linus Walleij <linus.walleij@...aro.org>, linux-gpio@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH v4 8/8] gpiolib: notify user-space about in-kernel line
 state changes

On Thu, Oct 17, 2024 at 10:14:16AM +0200, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
>
> @@ -1447,8 +1450,6 @@ static long linereq_set_config(struct linereq *lr, void __user *ip)
>  		}
>
>  		WRITE_ONCE(line->edflags, edflags);
> -
> -		gpiod_line_state_notify(desc, GPIO_V2_LINE_CHANGED_CONFIG);
>  	}
>  	return 0;
>  }

I still get errors from this when reconfiguring lines with debounce.
You should leave this notify in place and use _nonotify when setting the
direction.
i.e.

@@ -1436,11 +1432,11 @@ static long linereq_set_config(struct linereq *lr, void __user *ip)
                        int val = gpio_v2_line_config_output_value(&lc, i);

                        edge_detector_stop(line);
-                       ret = gpiod_direction_output(desc, val);
+                       ret = gpiod_direction_output_nonotify(desc, val);
                        if (ret)
                                return ret;
                } else {
-                       ret = gpiod_direction_input(desc);
+                       ret = gpiod_direction_input_nonotify(desc);
                        if (ret)
                                return ret;

@@ -1450,6 +1446,8 @@ static long linereq_set_config(struct linereq *lr, void __user *ip)
                }

                WRITE_ONCE(line->edflags, edflags);
+
+               gpiod_line_state_notify(desc, GPIO_V2_LINE_CHANGED_CONFIG);
        }
        return 0;
 }

Given that, all my current tests are passing.

Cheers,
Kent.