From patchwork Thu Jul 17 15:43:00 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sebastian Andrzej Siewior X-Patchwork-Id: 4576381 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id E65C7C0514 for ; Thu, 17 Jul 2014 15:45:19 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 1C6CB2017D for ; Thu, 17 Jul 2014 15:45:19 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 42FC62018E for ; Thu, 17 Jul 2014 15:45:18 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1X7nqE-0002MS-FJ; Thu, 17 Jul 2014 15:43:30 +0000 Received: from galois.linutronix.de ([2001:470:1f0b:db:abcd:42:0:1]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1X7nq9-0002DQ-Vm for linux-arm-kernel@lists.infradead.org; Thu, 17 Jul 2014 15:43:27 +0000 Received: from bigeasy by Galois.linutronix.de with local (Exim 4.80) (envelope-from ) id 1X7npk-0004OB-UH; Thu, 17 Jul 2014 17:43:00 +0200 Date: Thu, 17 Jul 2014 17:43:00 +0200 From: Sebastian Andrzej Siewior To: Peter Hurley Subject: Re: [PATCH 4/5] tty: serial: 8250 core: add runtime pm Message-ID: <20140717154300.GA16623@linutronix.de> References: <1405521903-5877-1-git-send-email-bigeasy@linutronix.de> <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> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <53C7EC6F.6060902@hurleysoftware.com> X-Key-Id: 97C4700B X-Key-Fingerprint: 09E2 D1F3 9A3A FF13 C3D3 961C 0688 1C1E 97C4 700B User-Agent: Mutt/1.5.21 (2010-09-15) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20140717_084326_184009_1AAB2FC7 X-CRM114-Status: GOOD ( 11.60 ) X-Spam-Score: -0.0 (/) Cc: Tony Lindgren , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, balbi@ti.com, linux-serial@vger.kernel.org, linux-omap@vger.kernel.org, mika.westerberg@linux.intel.com, linux-arm-kernel@lists.infradead.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP * Peter Hurley | 2014-07-17 11:31:59 [-0400]: >On 07/16/2014 12:06 PM, Felipe Balbi wrote: >>On Wed, Jul 16, 2014 at 05:54:56PM +0200, Sebastian Andrzej Siewior wrote: >>>On 07/16/2014 05:16 PM, Felipe Balbi wrote: > >>>>I wonder if you should get_sync() on start_tx() and only >>>>put_autosuspend() at stop_tx(). I guess the outcome would be >>>>largely the same, no ? >>> >>>I just opened minicom on ttyS0 and gave a try. start_tx() was invoked >>>each time I pressed a key (sent a character). I haven't seen stop_tx() >>>even after after I closed minicom. I guess stop_tx() is invoked if you >>>switch half-duplex communication. >> >>that's bad, I expected stop to be called also after each character. > >The 8250 core auto-stops tx when the tx ring buffer is empty (except >in the case of dma, where stopping tx isn't necessary). This is correct. So this is what I have now for the non-dma case: and now I need to come up with something that is not if (port != omap) for that #if 0 block. The code disables the TX FIFO empty interrupt once the transfer is complete. I want to call __stop_tx() once the tx fifo is empty. Felipe, Would a check for dev->power.use_autosuspend be the right thing to do? >Regards, >Peter Hurley Sebastian diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c index 2e4a93b..480a1c0 100644 --- a/drivers/tty/serial/8250/8250_core.c +++ b/drivers/tty/serial/8250/8250_core.c @@ -1283,6 +1283,9 @@ static inline void __stop_tx(struct uart_8250_port *p) if (p->ier & UART_IER_THRI) { p->ier &= ~UART_IER_THRI; serial_out(p, UART_IER, p->ier); + + pm_runtime_mark_last_busy(p->port.dev); + pm_runtime_put_autosuspend(p->port.dev); } } @@ -1310,12 +1313,12 @@ static void serial8250_start_tx(struct uart_port *port) struct uart_8250_port *up = container_of(port, struct uart_8250_port, port); - pm_runtime_get_sync(port->dev); if (up->dma && !serial8250_tx_dma(up)) { goto out; } else if (!(up->ier & UART_IER_THRI)) { up->ier |= UART_IER_THRI; + pm_runtime_get_sync(port->dev); serial_port_out(port, UART_IER, up->ier); if (up->bugs & UART_BUG_TXEN) { unsigned char lsr; @@ -1500,9 +1503,10 @@ void serial8250_tx_chars(struct uart_8250_port *up) uart_write_wakeup(port); DEBUG_INTR("THRE..."); - +#if 0 if (uart_circ_empty(xmit)) __stop_tx(up); +#endif } EXPORT_SYMBOL_GPL(serial8250_tx_chars);