From patchwork Fri Sep 5 19:02:44 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: 4854131 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 698BF9F314 for ; Fri, 5 Sep 2014 19:06:13 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 7D0E6201D3 for ; Fri, 5 Sep 2014 19:06:12 +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 97055200E1 for ; Fri, 5 Sep 2014 19:06:11 +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 1XPynw-0008MX-8E; Fri, 05 Sep 2014 19:04:16 +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 1XPynE-0007iF-El for linux-arm-kernel@lists.infradead.org; Fri, 05 Sep 2014 19:03:34 +0000 Received: from localhost ([127.0.0.1] helo=bazinga.breakpoint.cc) by Galois.linutronix.de with esmtp (Exim 4.80) (envelope-from ) id 1XPymu-0002uU-KR; Fri, 05 Sep 2014 21:03:12 +0200 From: Sebastian Andrzej Siewior To: linux-serial@vger.kernel.org Subject: [PATCH 09/18] tty: serial: 8250_dma: handle error on TX submit Date: Fri, 5 Sep 2014 21:02:44 +0200 Message-Id: <1409943773-7874-10-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> 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_120332_690118_70E57A88 X-CRM114-Status: GOOD ( 13.07 ) X-Spam-Score: -1.7 (-) Cc: tony@atomide.com, Greg Kroah-Hartman , Sebastian Andrzej Siewior , linux-kernel@vger.kernel.org, balbi@ti.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: , MIME-Version: 1.0 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 Right now it is possible that serial8250_tx_dma() fails and returns -EBUSY. The caller (serial8250_start_tx()) will then enable UART_IER_THRI which will generate an interrupt once the TX FIFO is empty. In serial8250_handle_irq() nothing will happen because up->dma is set and so serial8250_tx_chars() won't be invoked. We end up with plenty of interrupts and some "too much work for irq" output. This patch introduces dma_tx_err in struct uart_8250_port to signal that the last invocation of serial8250_tx_dma() failed so we can fill the TX FIFO manually. Should the next invocation of serial8250_start_tx() succeed then the dma_tx_err flag along with the THRI bit is removed and DMA only usage may continue. Signed-off-by: Sebastian Andrzej Siewior --- drivers/tty/serial/8250/8250.h | 1 + drivers/tty/serial/8250/8250_core.c | 4 +++- drivers/tty/serial/8250/8250_dma.c | 30 +++++++++++++++++++++++++----- 3 files changed, 29 insertions(+), 6 deletions(-) diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h index 1bcb4b2141a6..a63d198f8d03 100644 --- a/drivers/tty/serial/8250/8250.h +++ b/drivers/tty/serial/8250/8250.h @@ -41,6 +41,7 @@ struct uart_8250_dma { size_t tx_size; unsigned char tx_running:1; + unsigned char tx_err: 1; }; struct old_serial_port { diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c index e8df7cd85ba7..2101134e5031 100644 --- a/drivers/tty/serial/8250/8250_core.c +++ b/drivers/tty/serial/8250/8250_core.c @@ -1592,8 +1592,10 @@ int serial8250_handle_irq(struct uart_port *port, unsigned int iir) status = serial8250_rx_chars(up, status); } serial8250_modem_status(up); - if (!up->dma && (status & UART_LSR_THRE)) + if ((!up->dma || (up->dma && up->dma->tx_err)) && + (status & UART_LSR_THRE)) { serial8250_tx_chars(up); + } spin_unlock_irqrestore(&port->lock, flags); return 1; diff --git a/drivers/tty/serial/8250/8250_dma.c b/drivers/tty/serial/8250/8250_dma.c index 148ffe4c232f..69e54abb6e71 100644 --- a/drivers/tty/serial/8250/8250_dma.c +++ b/drivers/tty/serial/8250/8250_dma.c @@ -36,8 +36,16 @@ static void __dma_tx_complete(void *param) if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) uart_write_wakeup(&p->port); - if (!uart_circ_empty(xmit) && !uart_tx_stopped(&p->port)) - serial8250_tx_dma(p); + if (!uart_circ_empty(xmit) && !uart_tx_stopped(&p->port)) { + int ret; + + ret = serial8250_tx_dma(p); + if (ret) { + dma->tx_err = 1; + p->ier |= UART_IER_THRI; + serial_port_out(&p->port, UART_IER, p->ier); + } + } spin_unlock_irqrestore(&p->port.lock, flags); } @@ -69,6 +77,7 @@ int serial8250_tx_dma(struct uart_8250_port *p) struct uart_8250_dma *dma = p->dma; struct circ_buf *xmit = &p->port.state->xmit; struct dma_async_tx_descriptor *desc; + int ret; if (uart_tx_stopped(&p->port) || dma->tx_running || uart_circ_empty(xmit)) @@ -80,8 +89,10 @@ int serial8250_tx_dma(struct uart_8250_port *p) dma->tx_addr + xmit->tail, dma->tx_size, DMA_MEM_TO_DEV, DMA_PREP_INTERRUPT | DMA_CTRL_ACK); - if (!desc) - return -EBUSY; + if (!desc) { + ret = -EBUSY; + goto err; + } dma->tx_running = 1; @@ -94,8 +105,17 @@ int serial8250_tx_dma(struct uart_8250_port *p) UART_XMIT_SIZE, DMA_TO_DEVICE); dma_async_issue_pending(dma->txchan); - + if (dma->tx_err) { + dma->tx_err = 0; + if (p->ier & UART_IER_THRI) { + p->ier &= ~UART_IER_THRI; + serial_out(p, UART_IER, p->ier); + } + } return 0; +err: + dma->tx_err = 1; + return ret; } EXPORT_SYMBOL_GPL(serial8250_tx_dma);