From mboxrd@z Thu Jan 1 00:00:00 1970 From: Geert Uytterhoeven Date: Fri, 18 Sep 2015 11:08:26 +0000 Subject: [PATCH v4 03/10] serial: sh-sci: Submit RX DMA from RX interrupt on (H)SCIF Message-Id: <1442574513-20648-4-git-send-email-geert+renesas@glider.be> List-Id: References: <1442574513-20648-1-git-send-email-geert+renesas@glider.be> In-Reply-To: <1442574513-20648-1-git-send-email-geert+renesas@glider.be> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Greg Kroah-Hartman , Jiri Slaby Cc: Muhammad Hamza Farooq , Magnus Damm , Yoshihiro Shimoda , Laurent Pinchart , Nobuhiro Iwamatsu , Yoshihiro Kaneko , Kazuya Mizuguchi , Koji Matsuoka , Wolfram Sang , Guennadi Liakhovetski , linux-serial@vger.kernel.org, linux-sh@vger.kernel.org, Geert Uytterhoeven For DMA receive requests, the driver is only notified by DMA completion after the whole DMA request has been transferred. If less data is received, it will stay stuck until more data arrives. The driver handles this by setting up a timer handler from the receive interrupt, after reception of the first character. Unlike SCIFA and SCIFB, SCIF and HSCIF don't issue receive interrupts on reception of individual characters if a receive DMA request is in progress, so the timer is never set up. To fix receive DMA on SCIF and HSCIF, submit the receive DMA request from the receive interrupt handler instead. In some sense this is similar to the SCIFA/SCIFB behavior, where the RDRQE (Rx Data Transfer Request Enable) bit is also set from the receive interrupt handler. Signed-off-by: Geert Uytterhoeven --- v4: - Dropped RFC status, - Rebased on top of "[PATCH] serial: sh-sci: Shuffle functions around", hence the forward declaration of sci_submit_rx() is no longer needed, and the declared-but-never-defined compiler warning if CONFIG_SERIAL_SH_SCI_DMA=n is gone. v3: - New, this replaces the one-byte DMA transfer from "[PATCH/RFC v2 28/29] serial: sh-sci: Add (H)SCIF DMA support". --- drivers/tty/serial/sh-sci.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c index eb2b369b1cf1be0b..02aaf4d213d9c280 100644 --- a/drivers/tty/serial/sh-sci.c +++ b/drivers/tty/serial/sh-sci.c @@ -1317,7 +1317,8 @@ static void rx_timer_fn(unsigned long arg) spin_unlock_irqrestore(&port->lock, flags); - sci_submit_rx(s); + if (port->type = PORT_SCIFA || port->type = PORT_SCIFB) + sci_submit_rx(s); } static void sci_request_dma(struct uart_port *port) @@ -1403,7 +1404,8 @@ static void sci_request_dma(struct uart_port *port) setup_timer(&s->rx_timer, rx_timer_fn, (unsigned long)s); - sci_submit_rx(s); + if (port->type = PORT_SCIFA || port->type = PORT_SCIFB) + sci_submit_rx(s); } } @@ -1442,6 +1444,7 @@ static irqreturn_t sci_rx_interrupt(int irq, void *ptr) scr |= SCSCR_RDRQE; } else { scr &= ~SCSCR_RIE; + sci_submit_rx(s); } serial_port_out(port, SCSCR, scr); /* Clear current interrupt */ -- 1.9.1