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




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