From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752186AbbBLTXm (ORCPT ); Thu, 12 Feb 2015 14:23:42 -0500 Received: from www.linutronix.de ([62.245.132.108]:57829 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751199AbbBLTXj (ORCPT ); Thu, 12 Feb 2015 14:23:39 -0500 Date: Thu, 12 Feb 2015 20:23:33 +0100 From: Sebastian Andrzej Siewior To: Peter Hurley Cc: Tony Lindgren , Nicolas Schichan , gregkh@linuxfoundation.org, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, balbi@ti.com, linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH 03/16] tty: serial: 8250_core: read only RX if there is something in the FIFO Message-ID: <20150212192333.GA18882@linutronix.de> References: <1410377411-26656-4-git-send-email-bigeasy@linutronix.de> <54D8B772.1010405@freebox.fr> <54D9441B.7070403@hurleysoftware.com> <54D9F3C7.5000809@freebox.fr> <54DA43F8.9090904@hurleysoftware.com> <54DBB531.2030504@hurleysoftware.com> <20150211200313.GE2531@atomide.com> <54DBBE9E.90104@hurleysoftware.com> <54DC6832.3070507@linutronix.de> <54DCD584.3010500@hurleysoftware.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <54DCD584.3010500@hurleysoftware.com> X-Key-Id: 97C4700B X-Key-Fingerprint: 09E2 D1F3 9A3A FF13 C3D3 961C 0688 1C1E 97C4 700B User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Peter Hurley | 2015-02-12 11:32:04 [-0500]: >That said, I don't think serial8250_do_startup() is really doing that much >for OMAP h/w startup; open-coding what omap_8250 really needs is probably >< 10 loc. 10 loc? I have a few more. serial8250_clear_fifos(), serial_link_irq_chain() aren't exported. serial8250_set_mctrl() can maybe accessed via uart_ops->set_mctrl(). Maybe I'm not removing the obvious not required code but here it looks better to just a BUG flag for the Omap. --- a/drivers/tty/serial/8250/8250_omap.c +++ b/drivers/tty/serial/8250/8250_omap.c @@ -557,9 +557,74 @@ static int omap_8250_startup(struct uart_port *port) pm_runtime_get_sync(port->dev); - ret = serial8250_do_startup(port); - if (ret) - goto err; + up->mcr = 0; + + /* + * Clear the FIFO buffers and disable them. + * (they will be reenabled in set_termios()) + */ + serial8250_clear_fifos(up); + + /* + * Clear the interrupt registers. + */ + if (serial_port_in(port, UART_LSR) & UART_LSR_DR) + serial_port_in(port, UART_RX); + serial_port_in(port, UART_IIR); + serial_port_in(port, UART_MSR); + + retval = serial_link_irq_chain(up); + if (retval) + goto out; + + /* + * Now, initialize the UART + */ + serial_port_out(port, UART_LCR, UART_LCR_WLEN8); + + spin_lock_irqsave(&port->lock, flags); + /* + * Most PC uarts need OUT2 raised to enable interrupts. + */ + if (port->irq) + up->port.mctrl |= TIOCM_OUT2; + + serial8250_set_mctrl(port, port->mctrl); + + spin_unlock_irqrestore(&port->lock, flags); + + /* + * Clear the interrupt registers again for luck, and clear the + * saved flags to avoid getting false values from polling + * routines or the previous session. + */ + if (serial_port_in(port, UART_LSR) & UART_LSR_DR) + serial_port_in(port, UART_RX); + serial_port_in(port, UART_IIR); + serial_port_in(port, UART_MSR); + up->lsr_saved_flags = 0; + up->msr_saved_flags = 0; + + /* + * Request DMA channels for both RX and TX. + */ + if (up->dma) { + retval = serial8250_request_dma(up); + if (retval) { + pr_warn_ratelimited("ttyS%d - failed to request DMA\n", + serial_index(port)); + up->dma = NULL; + } + } + + /* + * Finally, enable interrupts. Note: Modem status interrupts + * are set via set_termios(), which will be occurring imminently + * anyway, so we don't enable them here. + */ + up->ier = UART_IER_RLSI | UART_IER_RDI; + serial_port_out(port, UART_IER, up->ier); + #ifdef CONFIG_PM up->capabilities |= UART_CAP_RPM; Sebastian