On 12.08.17 20:46, Pavel Machek wrote: > On Sat 2017-08-12 14:34:02, Oleh Kravchenko wrote: >> On 12.08.17 13:56, Pavel Machek wrote: >>> Hi! >>> >>>>> On Sat 2017-08-12 12:09:35, Oleh Kravchenko wrote: >>>>>> This patch adds a LED class driver for the RGB LEDs found on >>>>>> the Crane Merchandising System CR0014114 LEDs board. >>>>> >>>>> What kind of hardware is this? >>>> >>>> It's from vending machines produced by Crane Merchandising System http://cranems.com/ >>>> >>>>>> Driver creates LED devices with name written using the following >>>>>> pattern "LABEL-{N}:{red,green,blue}:". >>>>> >>>>> Is the "-{N} suffix needed? >>>> >>>> It's number of RGB LED, board has 6 LEDs. >>> >>> Normally label differentiates them...? >> >> For example, possible names when two boards connected is: >> /sys/class/leds/board0-0:blue: >> /sys/class/leds/board0-0:green: >> /sys/class/leds/board0-0:red: > > Hmm. Well, this works if you can't provide better names. Still "board" > is somehow generic, andsomeone else might want to use it. "board" -> > "crms"? It's specified in device tree by defining label. In my examples: board@0 { compatible = "ccs,cr0014114"; reg = <0>; spi-max-frequency = <50000>; spi-cpha; label = "board0"; }; board@1 { compatible = "ccs,cr0014114"; reg = <1>; spi-max-frequency = <50000>; spi-cpha; label = "board1"; }; >>>>>> + while (i--) >>>>>> + led_classdev_unregister(&priv->leds[i].ldev); >>>>> >>>>> Can devm_* be used to simplify this? >>>> >>>> I think no, because it will cause race condition. >>> >>> Please take a look at devm_led_classdev_register() and friends. It >>> should be possible to simplify code without races. >> >> I don't understand how I can call destroy_workqueue() after calling unregister leds. > > Do you actually need the workqueues? It should be possible to avoid > them, using workqueue support in the core. The delay between data sends to SPI board should be at least 10 ms I think it will be bad idea to use shared workqueue from kernel, so I create separate single threaded work queue :) -- Best regards, Oleh Kravchenko
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