From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752924Ab2AQKaO (ORCPT ); Tue, 17 Jan 2012 05:30:14 -0500 Received: from eu1sys200aog111.obsmtp.com ([207.126.144.131]:51699 "EHLO eu1sys200aog111.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752400Ab2AQKaL (ORCPT ); Tue, 17 Jan 2012 05:30:11 -0500 From: Shreshtha Kumar SAHU To: , , Cc: , Shreshtha Kumar Sahu Subject: [PATCH] amba-pl011: do not disable RTS during shutdown Date: Tue, 17 Jan 2012 15:59:49 +0530 Message-ID: <1326796189-21722-1-git-send-email-shreshthakumar.sahu@stericsson.com> X-Mailer: git-send-email 1.7.4.3 MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Shreshtha Kumar Sahu In present driver, shutdown clears RTS in CR register. But the documentation "Documentation/serial/driver" suggests not to disable RTS in shutdown(). Also RTS is preserved between shutdown and startup calls, i.e. it is restored in startup if it was enabled during shutdown. So that if autorts is set and RTS is set using pl011_set_mctrl then it should continue even after shutdown->startup sequence. And hence during set_termios it will enable RTS only if RTS bit is set in UARTx_CR register. For throttling/unthrottling user should call pl011_set_mctrl. Change-Id: I743f33fb10e7e655657cd5dae1ec585e914a65bc Signed-off-by: Shreshtha Kumar Sahu Acked-by: Linus Walleij --- drivers/tty/serial/amba-pl011.c | 17 ++++++++++++++++- 1 files changed, 16 insertions(+), 1 deletions(-) diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c index 6958594..46a4690 100644 --- a/drivers/tty/serial/amba-pl011.c +++ b/drivers/tty/serial/amba-pl011.c @@ -160,6 +160,7 @@ struct uart_amba_port { unsigned int lcrh_tx; /* vendor-specific */ unsigned int lcrh_rx; /* vendor-specific */ bool autorts; + bool rts_state; /* state during shutdown */ char type[12]; bool interrupt_may_hang; /* vendor-specific */ #ifdef CONFIG_DMA_ENGINE @@ -1412,6 +1413,8 @@ static int pl011_startup(struct uart_port *port) barrier(); cr = UART01x_CR_UARTEN | UART011_CR_RXE | UART011_CR_TXE; + if (uap->rts_state) + cr |= UART011_CR_RTS; writew(cr, uap->port.membase + UART011_CR); /* Clear pending error interrupts */ @@ -1469,6 +1472,7 @@ static void pl011_shutdown_channel(struct uart_amba_port *uap, static void pl011_shutdown(struct uart_port *port) { struct uart_amba_port *uap = (struct uart_amba_port *)port; + unsigned int cr; /* * disable all interrupts @@ -1488,9 +1492,19 @@ static void pl011_shutdown(struct uart_port *port) /* * disable the port + * disable the port. It should not disable RTS. + * Also RTS state should be preserved to restore + * it during startup(). */ uap->autorts = false; - writew(UART01x_CR_UARTEN | UART011_CR_TXE, uap->port.membase + UART011_CR); + cr = readw(uap->port.membase + UART011_CR); + if (cr & UART011_CR_RTS) { + uap->rts_state = true; + cr = UART011_CR_RTS; + } else + uap->rts_state = false; + cr |= UART01x_CR_UARTEN | UART011_CR_TXE; + writew(cr, uap->port.membase + UART011_CR); /* * disable break condition and fifos @@ -1905,6 +1919,7 @@ static int pl011_probe(struct amba_device *dev, const struct amba_id *id) uap->vendor = vendor; uap->lcrh_rx = vendor->lcrh_rx; uap->lcrh_tx = vendor->lcrh_tx; + uap->rts_state = false; uap->fifosize = vendor->fifosize; uap->interrupt_may_hang = vendor->interrupt_may_hang; uap->port.dev = &dev->dev; -- 1.7.4.3