From patchwork Fri Jul 5 06:12:28 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Huang Shijie X-Patchwork-Id: 2823986 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 B60FB9F3EB for ; Fri, 5 Jul 2013 06:41:13 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 338552015D for ; Fri, 5 Jul 2013 06:41:12 +0000 (UTC) Received: from casper.infradead.org (casper.infradead.org [85.118.1.10]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E5A552015B for ; Fri, 5 Jul 2013 06:41:09 +0000 (UTC) Received: from merlin.infradead.org ([2001:4978:20e::2]) by casper.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1Uuzgj-0007TD-Ct; Fri, 05 Jul 2013 06:40:14 +0000 Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1UuzgT-0007Tr-UC; Fri, 05 Jul 2013 06:39:58 +0000 Received: from co1ehsobe002.messaging.microsoft.com ([216.32.180.185] helo=co1outboundpool.messaging.microsoft.com) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1UuzgH-0007Rt-7I for linux-arm-kernel@lists.infradead.org; Fri, 05 Jul 2013 06:39:47 +0000 Received: from mail199-co1-R.bigfish.com (10.243.78.240) by CO1EHSOBE006.bigfish.com (10.243.66.69) with Microsoft SMTP Server id 14.1.225.22; Fri, 5 Jul 2013 06:39:29 +0000 Received: from mail199-co1 (localhost [127.0.0.1]) by mail199-co1-R.bigfish.com (Postfix) with ESMTP id 33676380455; Fri, 5 Jul 2013 06:39:29 +0000 (UTC) X-Forefront-Antispam-Report: CIP:70.37.183.190; KIP:(null); UIP:(null); IPV:NLI; H:mail.freescale.net; RD:none; EFVD:NLI X-SpamScore: 6 X-BigFish: VS6(zcb8kzzz1f42h1ee6h1de0h1fdah2073h1202h1e76h1d1ah1d2ah1fc6h1082kzz8275bhz2dh2a8h668h839hd24he5bhf0ah1288h12a5h12a9h12bdh12e5h137ah139eh13b6h1441h1504h1537h162dh1631h1758h1898h18e1h1946h19b5h1ad9h1b0ah1d0ch1d2eh1d3fh1dfeh1dffh1e23h1155h) Received: from mail199-co1 (localhost.localdomain [127.0.0.1]) by mail199-co1 (MessageSwitch) id 1373006366393067_7391; Fri, 5 Jul 2013 06:39:26 +0000 (UTC) Received: from CO1EHSMHS005.bigfish.com (unknown [10.243.78.242]) by mail199-co1.bigfish.com (Postfix) with ESMTP id 5D347D80062; Fri, 5 Jul 2013 06:39:26 +0000 (UTC) Received: from mail.freescale.net (70.37.183.190) by CO1EHSMHS005.bigfish.com (10.243.66.15) with Microsoft SMTP Server (TLS) id 14.1.225.23; Fri, 5 Jul 2013 06:39:26 +0000 Received: from az84smr01.freescale.net (10.64.34.197) by 039-SN1MMR1-002.039d.mgd.msft.net (10.84.1.15) with Microsoft SMTP Server (TLS) id 14.2.328.11; Fri, 5 Jul 2013 06:39:24 +0000 Received: from shlinux2.ap.freescale.net (shlinux2.ap.freescale.net [10.192.224.44]) by az84smr01.freescale.net (8.14.3/8.14.0) with ESMTP id r656dHG1003101; Thu, 4 Jul 2013 23:39:22 -0700 From: Huang Shijie To: Subject: [PATCH v3 2/6] serial: imx: add DMA support for imx6q Date: Fri, 5 Jul 2013 14:12:28 +0800 Message-ID: <1373004752-21302-3-git-send-email-b32955@freescale.com> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1373004752-21302-1-git-send-email-b32955@freescale.com> References: <1373004752-21302-1-git-send-email-b32955@freescale.com> MIME-Version: 1.0 X-OriginatorOrg: freescale.com X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20130705_023945_503951_A27CFFF7 X-CRM114-Status: GOOD ( 25.65 ) X-Spam-Score: -2.6 (--) Cc: Huang Shijie , shawn.guo@linaro.org, linux-arm-kernel@lists.infradead.org, linux-serial@vger.kernel.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.15 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=-4.4 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, 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 We only enable the DMA support when the following are meet: [1] The uart port supports the hardware flow control(CTS/RTS). (Some uart port does not support the CTS/RTS.) [2] The application enables the CTS/RTS. [3] The Soc is imx6q. For the sdma's firmware limit, we do not support the DMA except the imx6q platform. [4] The uart is not used as a console. Signed-off-by: Huang Shijie --- drivers/tty/serial/imx.c | 405 +++++++++++++++++++++++++++++++++++++++++++++- 1 files changed, 400 insertions(+), 5 deletions(-) diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index a9643ef..d04a09e 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -49,9 +49,11 @@ #include #include #include +#include #include #include +#include /* Register definitions */ #define URXD0 0x0 /* Receiver Register */ @@ -83,6 +85,7 @@ #define UCR1_ADBR (1<<14) /* Auto detect baud rate */ #define UCR1_TRDYEN (1<<13) /* Transmitter ready interrupt enable */ #define UCR1_IDEN (1<<12) /* Idle condition interrupt */ +#define UCR1_ICD_REG(x) (((x) & 3) << 10) /* idle condition detect */ #define UCR1_RRDYEN (1<<9) /* Recv ready interrupt enable */ #define UCR1_RDMAEN (1<<8) /* Recv ready DMA enable */ #define UCR1_IREN (1<<7) /* Infrared interface enable */ @@ -91,6 +94,7 @@ #define UCR1_SNDBRK (1<<4) /* Send break */ #define UCR1_TDMAEN (1<<3) /* Transmitter ready DMA enable */ #define IMX1_UCR1_UARTCLKEN (1<<2) /* UART clock enabled, i.mx1 only */ +#define UCR1_ATDMAEN (1<<2) /* Aging DMA Timer Enable */ #define UCR1_DOZE (1<<1) /* Doze */ #define UCR1_UARTEN (1<<0) /* UART enabled */ #define UCR2_ESCI (1<<15) /* Escape seq interrupt enable */ @@ -126,6 +130,7 @@ #define UCR4_ENIRI (1<<8) /* Serial infrared interrupt enable */ #define UCR4_WKEN (1<<7) /* Wake interrupt enable */ #define UCR4_REF16 (1<<6) /* Ref freq 16 MHz */ +#define UCR4_IDDMAEN (1<<6) /* DMA IDLE Condition Detected */ #define UCR4_IRSC (1<<5) /* IR special case */ #define UCR4_TCEN (1<<3) /* Transmit complete interrupt enable */ #define UCR4_BKEN (1<<2) /* Break condition interrupt enable */ @@ -210,6 +215,19 @@ struct imx_port { struct clk *clk_ipg; struct clk *clk_per; const struct imx_uart_data *devdata; + + /* DMA fields */ + unsigned int dma_is_inited:1; + unsigned int dma_is_enabled:1; + unsigned int dma_is_rxing:1; + unsigned int dma_is_txing:1; + struct dma_chan *dma_chan_rx, *dma_chan_tx; + struct scatterlist rx_sgl, tx_sgl[2]; + void *rx_buf; + unsigned int rx_bytes, tx_bytes; + struct work_struct tsk_dma_rx, tsk_dma_tx; + unsigned int dma_tx_nents; + wait_queue_head_t dma_wait; }; struct imx_port_ucrs { @@ -400,6 +418,13 @@ static void imx_stop_tx(struct uart_port *port) return; } + /* + * We are maybe in the SMP context, so if the DMA TX thread is running + * on other cpu, we have to wait for it to finish. + */ + if (sport->dma_is_enabled && sport->dma_is_txing) + return; + temp = readl(sport->port.membase + UCR1); writel(temp & ~UCR1_TXMPTYEN, sport->port.membase + UCR1); } @@ -412,6 +437,13 @@ static void imx_stop_rx(struct uart_port *port) struct imx_port *sport = (struct imx_port *)port; unsigned long temp; + /* + * We are maybe in the SMP context, so if the DMA TX thread is running + * on other cpu, we have to wait for it to finish. + */ + if (sport->dma_is_enabled && sport->dma_is_rxing) + return; + temp = readl(sport->port.membase + UCR2); writel(temp & ~UCR2_RXEN, sport->port.membase + UCR2); } @@ -447,6 +479,95 @@ static inline void imx_transmit_buffer(struct imx_port *sport) imx_stop_tx(&sport->port); } +static void dma_tx_callback(void *data) +{ + struct imx_port *sport = data; + struct scatterlist *sgl = &sport->tx_sgl[0]; + struct circ_buf *xmit = &sport->port.state->xmit; + unsigned long flags; + + dma_unmap_sg(sport->port.dev, sgl, sport->dma_tx_nents, DMA_TO_DEVICE); + + sport->dma_is_txing = 0; + + /* update the stat */ + spin_lock_irqsave(&sport->port.lock, flags); + xmit->tail = (xmit->tail + sport->tx_bytes) & (UART_XMIT_SIZE - 1); + sport->port.icount.tx += sport->tx_bytes; + spin_unlock_irqrestore(&sport->port.lock, flags); + + dev_dbg(sport->port.dev, "we finish the TX DMA.\n"); + + if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) + uart_write_wakeup(&sport->port); + + if (waitqueue_active(&sport->dma_wait)) { + wake_up(&sport->dma_wait); + dev_dbg(sport->port.dev, "exit in %s.\n", __func__); + return; + } + + schedule_work(&sport->tsk_dma_tx); +} + +static void dma_tx_work(struct work_struct *w) +{ + struct imx_port *sport = container_of(w, struct imx_port, tsk_dma_tx); + struct circ_buf *xmit = &sport->port.state->xmit; + struct scatterlist *sgl = sport->tx_sgl; + struct dma_async_tx_descriptor *desc; + struct dma_chan *chan = sport->dma_chan_tx; + struct device *dev = sport->port.dev; + enum dma_status status; + unsigned long flags; + int ret; + + status = chan->device->device_tx_status(chan, (dma_cookie_t)0, NULL); + if (DMA_IN_PROGRESS == status) + return; + + spin_lock_irqsave(&sport->port.lock, flags); + sport->tx_bytes = uart_circ_chars_pending(xmit); + if (sport->tx_bytes == 0) { + spin_unlock_irqrestore(&sport->port.lock, flags); + return; + } + + if (xmit->tail > xmit->head) { + sport->dma_tx_nents = 2; + sg_init_table(sgl, 2); + sg_set_buf(sgl, xmit->buf + xmit->tail, + UART_XMIT_SIZE - xmit->tail); + sg_set_buf(sgl + 1, xmit->buf, xmit->head); + } else { + sport->dma_tx_nents = 1; + sg_init_one(sgl, xmit->buf + xmit->tail, sport->tx_bytes); + } + spin_unlock_irqrestore(&sport->port.lock, flags); + + ret = dma_map_sg(dev, sgl, sport->dma_tx_nents, DMA_TO_DEVICE); + if (ret == 0) { + dev_err(dev, "DMA mapping error for TX.\n"); + return; + } + desc = dmaengine_prep_slave_sg(chan, sgl, sport->dma_tx_nents, + DMA_MEM_TO_DEV, DMA_PREP_INTERRUPT); + if (!desc) { + dev_err(dev, "We cannot prepare for the TX slave dma!\n"); + return; + } + desc->callback = dma_tx_callback; + desc->callback_param = sport; + + dev_dbg(dev, "TX: prepare to send %lu bytes by DMA.\n", + uart_circ_chars_pending(xmit)); + /* fire it */ + sport->dma_is_txing = 1; + dmaengine_submit(desc); + dma_async_issue_pending(chan); + return; +} + /* * interrupts disabled on entry */ @@ -473,8 +594,10 @@ static void imx_start_tx(struct uart_port *port) temp |= UCR4_OREN; writel(temp, sport->port.membase + UCR4); - temp = readl(sport->port.membase + UCR1); - writel(temp | UCR1_TXMPTYEN, sport->port.membase + UCR1); + if (!sport->dma_is_enabled) { + temp = readl(sport->port.membase + UCR1); + writel(temp | UCR1_TXMPTYEN, sport->port.membase + UCR1); + } if (USE_IRDA(sport)) { temp = readl(sport->port.membase + UCR1); @@ -486,6 +609,15 @@ static void imx_start_tx(struct uart_port *port) writel(temp, sport->port.membase + UCR4); } + if (sport->dma_is_enabled) { + /* + * We may in the interrupt context, so arise a work_struct to + * do the real job. + */ + schedule_work(&sport->tsk_dma_tx); + return; + } + if (readl(sport->port.membase + uts_reg(sport)) & UTS_TXEMPTY) imx_transmit_buffer(sport); } @@ -601,6 +733,28 @@ out: return IRQ_HANDLED; } +/* + * If the RXFIFO is filled with some data, and then we + * arise a DMA operation to receive them. + */ +static void imx_dma_rxint(struct imx_port *sport) +{ + unsigned long temp; + + temp = readl(sport->port.membase + USR2); + if ((temp & USR2_RDR) && !sport->dma_is_rxing) { + sport->dma_is_rxing = 1; + + /* disable the `Recerver Ready Interrrupt` */ + temp = readl(sport->port.membase + UCR1); + temp &= ~(UCR1_RRDYEN); + writel(temp, sport->port.membase + UCR1); + + /* tell the DMA to receive the data. */ + schedule_work(&sport->tsk_dma_rx); + } +} + static irqreturn_t imx_int(int irq, void *dev_id) { struct imx_port *sport = dev_id; @@ -609,8 +763,12 @@ static irqreturn_t imx_int(int irq, void *dev_id) sts = readl(sport->port.membase + USR1); - if (sts & USR1_RRDY) - imx_rxint(irq, dev_id); + if (sts & USR1_RRDY) { + if (sport->dma_is_enabled) + imx_dma_rxint(sport); + else + imx_rxint(irq, dev_id); + } if (sts & USR1_TRDY && readl(sport->port.membase + UCR1) & UCR1_TXMPTYEN) @@ -667,7 +825,8 @@ static void imx_set_mctrl(struct uart_port *port, unsigned int mctrl) temp = readl(sport->port.membase + UCR2) & ~UCR2_CTS; if (mctrl & TIOCM_RTS) - temp |= UCR2_CTS; + if (!sport->dma_is_enabled) + temp |= UCR2_CTS; writel(temp, sport->port.membase + UCR2); } @@ -706,6 +865,226 @@ static int imx_setup_ufcr(struct imx_port *sport, unsigned int mode) return 0; } +#define RX_BUF_SIZE (PAGE_SIZE) +static int start_rx_dma(struct imx_port *sport); +static void dma_rx_work(struct work_struct *w) +{ + struct imx_port *sport = container_of(w, struct imx_port, tsk_dma_rx); + struct tty_port *port = &sport->port.state->port; + + if (sport->rx_bytes) { + tty_insert_flip_string(port, sport->rx_buf, sport->rx_bytes); + tty_flip_buffer_push(port); + sport->rx_bytes = 0; + } + + if (sport->dma_is_rxing) + start_rx_dma(sport); +} + +static void imx_rx_dma_done(struct imx_port *sport) +{ + unsigned long temp; + + /* Enable this interrupt when the RXFIFO is empty. */ + temp = readl(sport->port.membase + UCR1); + temp |= UCR1_RRDYEN; + writel(temp, sport->port.membase + UCR1); + + sport->dma_is_rxing = 0; + + /* Is the shutdown waiting for us? */ + if (waitqueue_active(&sport->dma_wait)) + wake_up(&sport->dma_wait); +} + +/* + * There are three kinds of RX DMA interrupts(such as in the MX6Q): + * [1] the RX DMA buffer is full. + * [2] the Aging timer expires(wait for 8 bytes long) + * [3] the Idle Condition Detect(enabled the UCR4_IDDMAEN). + * + * The [2] is trigger when a character was been sitting in the FIFO + * meanwhile [3] can wait for 32 bytes long when the RX line is + * on IDLE state and RxFIFO is empty. + */ +static void dma_rx_callback(void *data) +{ + struct imx_port *sport = data; + struct dma_chan *chan = sport->dma_chan_rx; + struct scatterlist *sgl = &sport->rx_sgl; + struct dma_tx_state state; + enum dma_status status; + unsigned int count; + + /* unmap it first */ + dma_unmap_sg(sport->port.dev, sgl, 1, DMA_FROM_DEVICE); + + status = chan->device->device_tx_status(chan, (dma_cookie_t)0, &state); + count = RX_BUF_SIZE - state.residue; + dev_dbg(sport->port.dev, "We get %d bytes.\n", count); + + if (count) { + sport->rx_bytes = count; + schedule_work(&sport->tsk_dma_rx); + } else + imx_rx_dma_done(sport); +} + +static int start_rx_dma(struct imx_port *sport) +{ + struct scatterlist *sgl = &sport->rx_sgl; + struct dma_chan *chan = sport->dma_chan_rx; + struct device *dev = sport->port.dev; + struct dma_async_tx_descriptor *desc; + int ret; + + sg_init_one(sgl, sport->rx_buf, RX_BUF_SIZE); + ret = dma_map_sg(dev, sgl, 1, DMA_FROM_DEVICE); + if (ret == 0) { + dev_err(dev, "DMA mapping error for RX.\n"); + return -EINVAL; + } + desc = dmaengine_prep_slave_sg(chan, sgl, 1, DMA_DEV_TO_MEM, + DMA_PREP_INTERRUPT); + if (!desc) { + dev_err(dev, "We cannot prepare for the RX slave dma!\n"); + return -EINVAL; + } + desc->callback = dma_rx_callback; + desc->callback_param = sport; + + dev_dbg(dev, "RX: prepare for the DMA.\n"); + dmaengine_submit(desc); + dma_async_issue_pending(chan); + return 0; +} + +static void imx_uart_dma_exit(struct imx_port *sport) +{ + if (sport->dma_chan_rx) { + dma_release_channel(sport->dma_chan_rx); + sport->dma_chan_rx = NULL; + + kfree(sport->rx_buf); + sport->rx_buf = NULL; + } + + if (sport->dma_chan_tx) { + dma_release_channel(sport->dma_chan_tx); + sport->dma_chan_tx = NULL; + } + + sport->dma_is_inited = 0; +} + +static int imx_uart_dma_init(struct imx_port *sport) +{ + struct dma_slave_config slave_config; + struct device *dev = sport->port.dev; + int ret; + + /* Prepare for RX : */ + sport->dma_chan_rx = dma_request_slave_channel(dev, "rx"); + if (!sport->dma_chan_rx) { + dev_dbg(dev, "cannot get the DMA channel.\n"); + ret = -EINVAL; + goto err; + } + + slave_config.direction = DMA_DEV_TO_MEM; + slave_config.src_addr = sport->port.mapbase + URXD0; + slave_config.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; + slave_config.src_maxburst = RXTL; + ret = dmaengine_slave_config(sport->dma_chan_rx, &slave_config); + if (ret) { + dev_err(dev, "error in RX dma configuration.\n"); + goto err; + } + + sport->rx_buf = kzalloc(PAGE_SIZE, GFP_KERNEL); + if (!sport->rx_buf) { + dev_err(dev, "cannot alloc DMA buffer.\n"); + ret = -ENOMEM; + goto err; + } + sport->rx_bytes = 0; + + /* Prepare for TX : */ + sport->dma_chan_tx = dma_request_slave_channel(dev, "tx"); + if (!sport->dma_chan_tx) { + dev_err(dev, "cannot get the TX DMA channel!\n"); + ret = -EINVAL; + goto err; + } + + slave_config.direction = DMA_MEM_TO_DEV; + slave_config.dst_addr = sport->port.mapbase + URTX0; + slave_config.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; + slave_config.dst_maxburst = TXTL; + ret = dmaengine_slave_config(sport->dma_chan_tx, &slave_config); + if (ret) { + dev_err(dev, "error in TX dma configuration."); + goto err; + } + + sport->dma_is_inited = 1; + + return 0; +err: + imx_uart_dma_exit(sport); + return ret; +} + +static void imx_enable_dma(struct imx_port *sport) +{ + unsigned long temp; + struct tty_port *port = &sport->port.state->port; + + port->low_latency = 1; + INIT_WORK(&sport->tsk_dma_tx, dma_tx_work); + INIT_WORK(&sport->tsk_dma_rx, dma_rx_work); + init_waitqueue_head(&sport->dma_wait); + + /* set UCR1 */ + temp = readl(sport->port.membase + UCR1); + temp |= UCR1_RDMAEN | UCR1_TDMAEN | UCR1_ATDMAEN | + /* wait for 32 idle frames for IDDMA interrupt */ + UCR1_ICD_REG(3); + writel(temp, sport->port.membase + UCR1); + + /* set UCR4 */ + temp = readl(sport->port.membase + UCR4); + temp |= UCR4_IDDMAEN; + writel(temp, sport->port.membase + UCR4); + + sport->dma_is_enabled = 1; +} + +static void imx_disable_dma(struct imx_port *sport) +{ + unsigned long temp; + struct tty_port *port = &sport->port.state->port; + + /* clear UCR1 */ + temp = readl(sport->port.membase + UCR1); + temp &= ~(UCR1_RDMAEN | UCR1_TDMAEN | UCR1_ATDMAEN); + writel(temp, sport->port.membase + UCR1); + + /* clear UCR2 */ + temp = readl(sport->port.membase + UCR2); + temp &= ~(UCR2_CTSC | UCR2_CTS); + writel(temp, sport->port.membase + UCR2); + + /* clear UCR4 */ + temp = readl(sport->port.membase + UCR4); + temp &= ~UCR4_IDDMAEN; + writel(temp, sport->port.membase + UCR4); + + sport->dma_is_enabled = 0; + port->low_latency = 0; +} + /* half the RX buffer size */ #define CTSTL 16 @@ -870,6 +1249,15 @@ static void imx_shutdown(struct uart_port *port) unsigned long temp; unsigned long flags; + if (sport->dma_is_enabled) { + /* We have to wait for the DMA to finish. */ + wait_event(sport->dma_wait, + !sport->dma_is_rxing && !sport->dma_is_txing); + imx_stop_rx(port); + imx_disable_dma(sport); + imx_uart_dma_exit(sport); + } + spin_lock_irqsave(&sport->port.lock, flags); temp = readl(sport->port.membase + UCR2); temp &= ~(UCR2_TXEN); @@ -956,6 +1344,11 @@ imx_set_termios(struct uart_port *port, struct ktermios *termios, if (sport->have_rtscts) { ucr2 &= ~UCR2_IRTS; ucr2 |= UCR2_CTSC; + + /* Can we enable the DMA support? */ + if (is_imx6q_uart(sport) && !uart_console(port) + && !sport->dma_is_inited) + imx_uart_dma_init(sport); } else { termios->c_cflag &= ~CRTSCTS; } @@ -1069,6 +1462,8 @@ imx_set_termios(struct uart_port *port, struct ktermios *termios, if (UART_ENABLE_MS(&sport->port, termios->c_cflag)) imx_enable_ms(&sport->port); + if (sport->dma_is_inited && !sport->dma_is_enabled) + imx_enable_dma(sport); spin_unlock_irqrestore(&sport->port.lock, flags); }