Re: [RESEND #2] [PATCH v2] LEDS: Add output invertion option to backlight trigger

Richard Purdie
2011-01-06T12:15:26Z

On Thu, 2011-01-06 at 16:08 +0900, Paul Mundt wrote:
> (Trying an alternate address for Richard, and adding Andrew to Cc..)
>
> On Thu, Dec 09, 2010 at 02:41:50PM +0100, Janusz Krzysztofik wrote:
> > This patch extends the LED backlight tirgger driver with an option that allows
> > for inverting the trigger output polarity.
> >
> > With the invertion option provided, I (ab)use the backlight trigger for
> > driving a LED that indicates LCD display blank condtition on my Amstrad Delta
> > videophone. Since the machine has no dedicated power LED, it was not possible
> > to distinguish if the display was blanked, or the machine was turned off,
> > without touching it.
> >
> > The invert sysfs control is patterned after a similiar function of the GPIO
> > trigger driver.
> >
> > Created and tested against linux-2.6.36-rc5 on Amstrad Delta.
> > Retested on linux-2.6.37-rc4.
> >
> > Signed-off-by: Janusz Krzysztofik <jkrzyszt@tis.icnet.pl>
> > Cc: Richard Purdie <rpurdie@rpsys.net>

Acked-by: Richard Purdie <richard.purdie@linuxfoundation.org>

I'll let Andrew take the patch though.

> > ---
> >
> > Resent because I still can't see any response received, while yet another
> > merge window is going to pass away soon.
> >
> > Applies cleanly on top of 2.6.37-rc4, so no need for yet another refresh. Only
> > tried to clean up the commit message slightly - maybe my English is not good
> > enough to bother with, if not the code?
> >
> > v1 -> v2 changes:
> > - improve some conditional expressions to be more readable; thanks to Ralph
> > Corderoy (from e3-hacking) and Lars-Peter Clausen for their suggestions,
> > - refresh against linux-2.6.36-rc5.
> >
> > drivers/leds/ledtrig-backlight.c | 60
> > ++++++++++++++++++++++++++++++++++++---
> > 1 file changed, 56 insertions(+), 4 deletions(-)
> >
> > diff -upr linux-2.6.36-rc5.orig/drivers/leds/ledtrig-backlight.c linux-2.6.36-rc5/drivers/leds/ledtrig-backlight.c
> > --- linux-2.6.36-rc5.orig/drivers/leds/ledtrig-backlight.c 2010-09-24 15:35:13.000000000 +0200
> > +++ linux-2.6.36-rc5/drivers/leds/ledtrig-backlight.c 2010-10-03 15:59:49.000000000 +0200
> > @@ -26,6 +26,7 @@ struct bl_trig_notifier {
> > int brightness;
> > int old_status;
> > struct notifier_block notifier;
> > + unsigned invert;
> > };
> >
> > static int fb_notifier_callback(struct notifier_block *p,
> > @@ -36,23 +37,63 @@ static int fb_notifier_callback(struct n
> > struct led_classdev *led = n->led;
> > struct fb_event *fb_event = data;
> > int *blank = fb_event->data;
> > + int new_status = *blank ? BLANK : UNBLANK;
> >
> > switch (event) {
> > case FB_EVENT_BLANK :
> > - if (*blank && n->old_status == UNBLANK) {
> > + if (new_status == n->old_status)
> > + break;
> > +
> > + if ((n->old_status == UNBLANK) ^ n->invert) {
> > n->brightness = led->brightness;
> > led_set_brightness(led, LED_OFF);
> > - n->old_status = BLANK;
> > - } else if (!*blank && n->old_status == BLANK) {
> > + } else {
> > led_set_brightness(led, n->brightness);
> > - n->old_status = UNBLANK;
> > }
> > +
> > + n->old_status = new_status;
> > +
> > break;
> > }
> >
> > return 0;
> > }
> >
> > +static ssize_t bl_trig_invert_show(struct device *dev,
> > + struct device_attribute *attr, char *buf)
> > +{
> > + struct led_classdev *led = dev_get_drvdata(dev);
> > + struct bl_trig_notifier *n = led->trigger_data;
> > +
> > + return sprintf(buf, "%s\n", n->invert ? "yes" : "no");
> > +}
> > +
> > +static ssize_t bl_trig_invert_store(struct device *dev,
> > + struct device_attribute *attr, const char *buf, size_t num)
> > +{
> > + struct led_classdev *led = dev_get_drvdata(dev);
> > + struct bl_trig_notifier *n = led->trigger_data;
> > + unsigned invert;
> > + int ret;
> > +
> > + ret = sscanf(buf, "%u", &invert);
> > + if (ret < 1) {
> > + dev_err(dev, "invalid value\n");
> > + return -EINVAL;
> > + }
> > +
> > + n->invert = !!invert;
> > +
> > + /* After inverting, we need to update the LED. */
> > + if ((n->old_status == BLANK) ^ n->invert)
> > + led_set_brightness(led, LED_OFF);
> > + else
> > + led_set_brightness(led, n->brightness);
> > +
> > + return num;
> > +}
> > +static DEVICE_ATTR(invert, 0644, bl_trig_invert_show, bl_trig_invert_store);
> > +
> > static void bl_trig_activate(struct led_classdev *led)
> > {
> > int ret;
> > @@ -66,6 +107,10 @@ static void bl_trig_activate(struct led_
> > return;
> > }
> >
> > + ret = device_create_file(led->dev, &dev_attr_invert);
> > + if (ret)
> > + goto err_invert;
> > +
> > n->led = led;
> > n->brightness = led->brightness;
> > n->old_status = UNBLANK;
> > @@ -74,6 +119,12 @@ static void bl_trig_activate(struct led_
> > ret = fb_register_client(&n->notifier);
> > if (ret)
> > dev_err(led->dev, "unable to register backlight trigger\n");
> > +
> > + return;
> > +
> > +err_invert:
> > + led->trigger_data = NULL;
> > + kfree(n);
> > }
> >
> > static void bl_trig_deactivate(struct led_classdev *led)
> > @@ -82,6 +133,7 @@ static void bl_trig_deactivate(struct le
> > (struct bl_trig_notifier *) led->trigger_data;
> >
> > if (n) {
> > + device_remove_file(led->dev, &dev_attr_invert);
> > fb_unregister_client(&n->notifier);
> > kfree(n);
> > }
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at http://vger.kernel.org/majordomo-info.html
>