Messages in this thread | | | Date | Thu, 24 Nov 2016 09:26:26 +0100 | From | Sascha Hauer <> | Subject | Re: [PATCH 1/4] serial: core: Add LED trigger support |
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On Wed, Nov 23, 2016 at 11:08:19AM +0100, Greg Kroah-Hartman wrote: > On Wed, Nov 23, 2016 at 11:01:03AM +0100, Sascha Hauer wrote: > > With this patch the serial core provides LED triggers for RX and TX. > > > > As the serial core layer does not know when the hardware actually sends > > or receives characters, this needs help from the UART drivers. The > > LED triggers are registered in uart_add_led_triggers() called from > > the UART drivers which want to support LED triggers. All the driver > > has to do then is to call uart_led_trigger_[tx|rx] to indicate > > activity.
BTW last time LED triggers were discussed (https://patchwork.kernel.org/patch/9212885/) You and Arnd mandated the triggers should be implemented in the tty layer. By tty layer did you really mean the tty layer or did you mean serial_core?
We could implement it in the tty layer, but tty doesn't know when the characters are actually sent. There could be arbitrary time passing between a tty_operations->put_char and the character being on the wire.
Also I am not sure if we want to have LED triggers for each and every tty in the system
Sascha
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