From patchwork Wed Sep 10 19:30:06 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: 4880571 Return-Path: X-Original-To: patchwork-linux-omap@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 6DC749F32E for ; Wed, 10 Sep 2014 19:57:54 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 87606201DD for ; Wed, 10 Sep 2014 19:57:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 99FF7201BC for ; Wed, 10 Sep 2014 19:57:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753636AbaIJT5u (ORCPT ); Wed, 10 Sep 2014 15:57:50 -0400 Received: from www.linutronix.de ([62.245.132.108]:35682 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752714AbaIJT5t (ORCPT ); Wed, 10 Sep 2014 15:57:49 -0400 Received: from localhost ([127.0.0.1] helo=bazinga.breakpoint.cc) by Galois.linutronix.de with esmtp (Exim 4.80) (envelope-from ) id 1XRnat-0001bs-W7; Wed, 10 Sep 2014 21:30:20 +0200 From: Sebastian Andrzej Siewior To: linux-serial@vger.kernel.org Cc: linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, tony@atomide.com, balbi@ti.com, gregkh@linuxfoundation.org, Sebastian Andrzej Siewior , vinod.koul@intel.com Subject: [PATCH 11/16] tty: serial: 8250_dma: keep own book keeping about RX transfers Date: Wed, 10 Sep 2014 21:30:06 +0200 Message-Id: <1410377411-26656-12-git-send-email-bigeasy@linutronix.de> X-Mailer: git-send-email 2.1.0 In-Reply-To: <1410377411-26656-1-git-send-email-bigeasy@linutronix.de> References: <1410377411-26656-1-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 Sender: linux-omap-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-omap@vger.kernel.org X-Spam-Status: No, score=-9.4 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, 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 Reviewed-by: Tony Lindgren Tested-by: Tony Lindgren 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 e836d128e63a..fa1dc966f394 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); @@ -173,21 +174,21 @@ 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); } @@ -196,7 +197,7 @@ 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, @@ -205,6 +206,7 @@ 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;