From patchwork Fri Sep 5 19:02:48 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Sebastian Andrzej Siewior X-Patchwork-Id: 4854441 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id E34999F32F for ; Fri, 5 Sep 2014 19:29:10 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 16E4520138 for ; Fri, 5 Sep 2014 19:29:10 +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 01CD42012F for ; Fri, 5 Sep 2014 19:29:09 +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 1XPzAK-0005yU-QF; Fri, 05 Sep 2014 19:27:24 +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 1XPzAH-0005ef-JV for linux-arm-kernel@lists.infradead.org; Fri, 05 Sep 2014 19:27:22 +0000 Received: from localhost ([127.0.0.1] helo=bazinga.breakpoint.cc) by Galois.linutronix.de with esmtp (Exim 4.80) (envelope-from ) id 1XPymw-0002uU-FA; Fri, 05 Sep 2014 21:03:14 +0200 From: Sebastian Andrzej Siewior To: linux-serial@vger.kernel.org Subject: [PATCH 13/18] tty: serial: 8250_dma: keep own book keeping about RX transfers Date: Fri, 5 Sep 2014 21:02:48 +0200 Message-Id: <1409943773-7874-14-git-send-email-bigeasy@linutronix.de> X-Mailer: git-send-email 2.1.0 In-Reply-To: <1409943773-7874-1-git-send-email-bigeasy@linutronix.de> References: <1409943773-7874-1-git-send-email-bigeasy@linutronix.de> MIME-Version: 1.0 X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1, SHORTCIRCUIT=-0.0001 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20140905_122721_809607_A4CC4A91 X-CRM114-Status: GOOD ( 16.80 ) X-Spam-Score: -1.7 (-) Cc: tony@atomide.com, Greg Kroah-Hartman , Sebastian Andrzej Siewior , linux-kernel@vger.kernel.org, balbi@ti.com, vinod.koul@intel.com, linux-omap@vger.kernel.org, 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=-3.6 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_NONE, 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 After dmaengine_terminate_all() has been invoked then both DMA drivers (edma and omap-dma) do not invoke dma_cookie_complete() to mark the transfer as complete. This dma_cookie_complete() is performed by the Synopsys DesignWare driver which is probably the only one that is used by omap8250-dma and hence don't see following problem… …which is that once a RX transfer has been terminated then following query of channel status reports DMA_IN_PROGRESS (again: the actual transfer has been canceled, there is nothing going on anymore). This means that serial8250_rx_dma() never enqueues another DMA transfer because it (wrongly) assumes that there is a transer already pending. Vinod Koul refuses to accept a patch which adds this dma_cookie_complete() to both drivers and so dmaengine_tx_status() would report DMA_COMPLETE instead (and behave like the Synopsys DesignWare driver already does). He argues that I am not allowed to use the cookie to query the status and that the driver already cleaned everything up after the invokation of dmaengine_terminate_all(). To end this I add a bookkeeping whether or not a RX-transfer has been started to the 8250-dma code. It has already been done for the TX side. *Now* we learn about the RX status based on our bookkeeping and don't need dmaengine_tx_status() for this anymore. Cc: vinod.koul@intel.com Signed-off-by: Sebastian Andrzej Siewior --- drivers/tty/serial/8250/8250.h | 1 + drivers/tty/serial/8250/8250_dma.c | 14 ++++++++------ 2 files changed, 9 insertions(+), 6 deletions(-) diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h index 09489b391568..a7581b37f264 100644 --- a/drivers/tty/serial/8250/8250.h +++ b/drivers/tty/serial/8250/8250.h @@ -42,6 +42,7 @@ struct uart_8250_dma { unsigned char tx_running:1; unsigned char tx_err: 1; + unsigned char rx_running:1; }; struct old_serial_port { diff --git a/drivers/tty/serial/8250/8250_dma.c b/drivers/tty/serial/8250/8250_dma.c index 48dc57aad0dd..6cd8a4db609a 100644 --- a/drivers/tty/serial/8250/8250_dma.c +++ b/drivers/tty/serial/8250/8250_dma.c @@ -60,6 +60,7 @@ static void __dma_rx_do_complete(struct uart_8250_port *p, bool error) dma_sync_single_for_cpu(dma->rxchan->device->dev, dma->rx_addr, dma->rx_size, DMA_FROM_DEVICE); + dma->rx_running = 0; dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state); dmaengine_terminate_all(dma->rxchan); @@ -162,21 +163,21 @@ int serial8250_rx_dma(struct uart_8250_port *p, unsigned int iir) { struct uart_8250_dma *dma = p->dma; struct dma_async_tx_descriptor *desc; - struct dma_tx_state state; - int dma_status; - - dma_status = dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state); switch (iir & 0x3f) { case UART_IIR_RLSI: /* 8250_core handles errors and break interrupts */ + if (dma->rx_running) { + dmaengine_pause(dma->rxchan); + __dma_rx_do_complete(p, true); + } return -EIO; case UART_IIR_RX_TIMEOUT: /* * If RCVR FIFO trigger level was not reached, complete the * transfer and let 8250_core copy the remaining data. */ - if (dma_status == DMA_IN_PROGRESS) { + if (dma->rx_running) { dmaengine_pause(dma->rxchan); __dma_rx_do_complete(p, true); } @@ -185,7 +186,7 @@ int serial8250_rx_dma(struct uart_8250_port *p, unsigned int iir) break; } - if (dma_status) + if (dma->rx_running) return 0; desc = dmaengine_prep_slave_single(dma->rxchan, dma->rx_addr, @@ -194,6 +195,7 @@ int serial8250_rx_dma(struct uart_8250_port *p, unsigned int iir) if (!desc) return -EBUSY; + dma->rx_running = 1; desc->callback = __dma_rx_complete; desc->callback_param = p;