linux-kernel - Re: [RFC PATCH 2/2] fbcon: expose cursor blink interval via sysfs

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Message-ID: <54C62E4B.3070009@ti.com>
Date:	Mon, 26 Jan 2015 14:08:43 +0200
From:	Tomi Valkeinen <tomi.valkeinen@...com>
To:	Scot Doyle <lkml14@...tdoyle.com>,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>
CC:	<linux-fbdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 2/2] fbcon: expose cursor blink interval via sysfs

On 24/01/15 03:19, Scot Doyle wrote:
> The fbcon cursor, when set to blink, is hardcoded to toggle display state
> five times per second. Expose this setting via
> /sys/class/graphics/fbcon/cursor_blink_ms
> 
> Values written to the interface set the approximate time interval in
> milliseconds between cursor toggles, from 1 to 32767. Since the interval
> is stored internally as a number of jiffies, the millisecond value read
> from the interface may not exactly match the entered value.
> 
> An outstanding blink timer is reset after a new value is entered.
> 
> If the cursor blink is disabled, either via the 'cursor_blink' boolean
> setting or some other mechanism, the 'cursor_blink_ms' setting may still
> be modified. The new value will be used if the blink is reactivated.
> 
> Tested with intelfb.
> 
> Signed-off-by: Scot Doyle <lkml14@...tdoyle.com>
> ---
>  drivers/video/console/fbcon.c | 75 +++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 75 insertions(+)
> 
> diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c
> index 7a2030b..0ddfcf6 100644
> --- a/drivers/video/console/fbcon.c
> +++ b/drivers/video/console/fbcon.c
> @@ -3495,11 +3495,86 @@ err:
>  	return count;
>  }
>  
> +static ssize_t show_cursor_blink_ms(struct device *device,
> +				    struct device_attribute *attr, char *buf)
> +{
> +	struct fb_info *info;
> +	struct fbcon_ops *ops;
> +	int idx, ms = -1;
> +
> +	if (fbcon_has_exited)
> +		return 0;

Why not return an error here?

> +
> +	console_lock();
> +	idx = con2fb_map[fg_console];
> +
> +	if (idx == -1 || registered_fb[idx] == NULL)
> +		goto err;

Same here?

> +	info = registered_fb[idx];
> +	ops = info->fbcon_par;
> +
> +	if (!ops)
> +		goto err;

And here.

> +
> +	ms = jiffies_to_msecs(ops->blink_jiffies);
> +
> +err:
> +	console_unlock();
> +	return snprintf(buf, PAGE_SIZE, "%d\n", ms);
> +}
> +
> +static ssize_t store_cursor_blink_ms(struct device *device,
> +				     struct device_attribute *attr,
> +				     const char *buf, size_t count)
> +{
> +	struct fb_info *info;
> +	struct fbcon_ops *ops;
> +	int idx;
> +	unsigned long ms;
> +
> +	if (fbcon_has_exited)
> +		return count;
> +
> +	console_lock();
> +	idx = con2fb_map[fg_console];
> +
> +	if (idx == -1 || registered_fb[idx] == NULL)
> +		goto err;
> +
> +	info = registered_fb[idx];
> +
> +	if (!info->fbcon_par)
> +		goto err;
> +
> +	ops = info->fbcon_par;
> +
> +	if (!ops)
> +		goto err;

Here also all the above look like errors to me, so why not return an error?

> +
> +	if (!kstrtoul(buf, 0, &ms)) {
> +		ms = min_t(unsigned long, ms, SHRT_MAX);
> +		ops->blink_jiffies = max_t(int, msecs_to_jiffies(ms), 1);
> +
> +		if (info->queue.func == fb_flashcursor &&
> +		    ops->flags & FBCON_FLAGS_CURSOR_TIMER) {
> +			fbcon_del_cursor_timer(info);
> +			fbcon_add_cursor_timer(info);
> +		}
> +	}
> +
> +err:
> +	console_unlock();
> +	return count;
> +}
> +
>  static struct device_attribute device_attrs[] = {
>  	__ATTR(rotate, S_IRUGO|S_IWUSR, show_rotate, store_rotate),
>  	__ATTR(rotate_all, S_IWUSR, NULL, store_rotate_all),
>  	__ATTR(cursor_blink, S_IRUGO|S_IWUSR, show_cursor_blink,
>  	       store_cursor_blink),
> +	__ATTR(cursor_blink_ms, S_IRUGO|S_IWUSR, show_cursor_blink_ms,
> +	       store_cursor_blink_ms),
>  };
>  
>  static int fbcon_init_device(void)
> 



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