From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Hurley Subject: Re: [PATCH 4/5] tty: serial: 8250 core: add runtime pm Date: Fri, 18 Jul 2014 11:53:21 -0400 Message-ID: <53C942F1.2000408@hurleysoftware.com> References: <1405521903-5877-5-git-send-email-bigeasy@linutronix.de> <20140716151604.GG1365@saruman.home> <53C6A050.2050409@linutronix.de> <20140716160614.GI1365@saruman.home> <53C7EC6F.6060902@hurleysoftware.com> <20140717154300.GA16623@linutronix.de> <20140717160206.GI10459@saruman.home> <53C7F4A3.5080508@linutronix.de> <20140717161848.GK10459@saruman.home> <53C8DC3E.3020701@linutronix.de> <20140718153116.GN24914@saruman.home> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20140718153116.GN24914@saruman.home> Sender: linux-kernel-owner@vger.kernel.org To: balbi@ti.com, Sebastian Andrzej Siewior Cc: linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Tony Lindgren , linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, Greg Kroah-Hartman , mika.westerberg@linux.intel.com List-Id: linux-serial@vger.kernel.org On 07/18/2014 11:31 AM, Felipe Balbi wrote: > On Fri, Jul 18, 2014 at 10:35:10AM +0200, Sebastian Andrzej Siewior wrote: >> >On 07/17/2014 06:18 PM, Felipe Balbi wrote: >> > >>>> > >>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. Regards, Peter Hurley