>>>>> "Andy" == Andy Walls <awalls@xxxxxxxxxxxxxxxx> writes: Hi, Andy> Given choices I made when I patched up gspca/cpia1.c for my Andy> prototype LED API usage, I got these associations Andy> By exposed LED name: Andy> /sys/class/leds/video0:white:illuminator0 Indeed. But didn't we just decide that illuminators were an integral part of the video handling (similar to gain control), and only use the LED API for status LEDs that don't directly interfere with the video data? Andy> The LED API has some shortcomings/annoyances: Andy> - The method a driver provides to set the LED brightness cannot sleep, Andy> so a workqueue is needed to simply turn a hardware light on and off for Andy> USB devices. Andy> - The Documentation is not very good for end-users or kernel developers Andy> on using the LED API. No? I agree that the documentation is pretty minimalistic, but ok - It's not that complicated. Andy> - For an LED trigger not to override a user's desire to inhibit an LED, Andy> the user needs to know to cancel all the triggers on an LED before Andy> setting the LEDs brightness to 0. Only a single trigger can be active at a time for a given LED. Andy> Again, that happens to be the only real compelling use case I see for Andy> using the LED API. However, I doubt many users will try to take Andy> advantage of it, and I suspect even less will succeed in getting it Andy> configured right. Good documentation could go a long way in correcting Andy> that. That and using the LED for something else (perhaps with another trigger like I eplained earlier with wlan/hdd activity). Andy> If a user configures multiple LED triggers on an LED, those triggers Andy> will compete with each other. The net result is the most recent event Andy> from the driver, any LED triggers wins, or user manipulation of sysfs Andy> brightness. Only a single trigger can be active at a time for a given LED. Andy> With indicators that's annoying, but not a failure. With illuminators, Andy> that is a failure. Again, I don't think we should use the LED API for something as integral to the video signal as illuminators. -- Bye, Peter Korsgaard -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
