Thread (31 messages) 31 messages, 4 authors, 2014-08-13

[PATCH 4/5] tty: serial: 8250 core: add runtime pm

From: Felipe Balbi <hidden>
Date: 2014-07-18 16:02:58
Also in: linux-omap, linux-serial, lkml

On Fri, Jul 18, 2014 at 11:53:21AM -0400, Peter Hurley wrote:
On 07/18/2014 11:31 AM, Felipe Balbi wrote:
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On Fri, Jul 18, 2014 at 10:35:10AM +0200, Sebastian Andrzej Siewior wrote:
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On 07/17/2014 06:18 PM, Felipe Balbi wrote:
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No, this is okay. If you look, it checks for "up->ier &
UART_IER_THRI". On the second invocation it will see that this
bit is already set and therefore won't call get_sync() for the
second time. That bit is removed in the _stop_tx() path.
oh, right. But that's actually unnecessary. Calling
pm_runtime_get() multiple times will just increment the usage
counter multiple times, which means you can call __stop_tx()
multiple times too and everything gets balanced, right ?
No. start_tx() will be called multiple times but only the first
invocation invoke pm_runtime_get(). Now I noticed that I forgot to
right, but that's unnecessary. You can pm_runtime_get() every time
start_tx() is called. Just make sure to put everytime stop_tx() is
called too.
The interface is asymmetric.

start_tx() may be invoked multiple times for which only 1 interrupt
will occur, and thus only invoke __stop_tx() once.
alright, thanks for the info.

-- 
balbi
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