Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753341AbaFMUSm (ORCPT ); Fri, 13 Jun 2014 16:18:42 -0400 Received: from filtteri5.pp.htv.fi ([213.243.153.188]:43671 "EHLO filtteri5.pp.htv.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751456AbaFMUSk (ORCPT ); Fri, 13 Jun 2014 16:18:40 -0400 Date: Fri, 13 Jun 2014 23:18:31 +0300 From: Aaro Koskinen To: Peter Hurley , Benjamin Herrenschmidt Cc: David Miller , linux-kernel@vger.kernel.org, sparclinux@vger.kernel.org, Greg Kroah-Hartman , Seth Bollinger Subject: Re: Linux 3.15: serial console regression Message-ID: <20140613201831.GA2360@drone.musicnaut.iki.fi> References: <20140609205917.GA913@drone.musicnaut.iki.fi> <1402357697-20976-1-git-send-email-peter@hurleysoftware.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1402357697-20976-1-git-send-email-peter@hurleysoftware.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Mon, Jun 09, 2014 at 07:48:17PM -0400, Peter Hurley wrote: > On 06/09/2014 04:59 PM, Aaro Koskinen wrote:> Hi, > > While testing the final 3.15, I noticed the serial console (sunsab) > > does not work anymore on Sun Ultra. > > > > It will tx fine the console output during the boot. But then I try > > to type something e.g. at the login: prompt, it behaves oddly: > > it re-transmits some old output, and then stalls for a few secs, usually > > for each character. Typed characters are however received correctly. > > But the console is impossible to use... > > > > I bisected this to: > > > > 717f3bbab3c7628736ef738fdbf3d9a28578c26c is the first bad commit > > commit 717f3bbab3c7628736ef738fdbf3d9a28578c26c > > Author: Seth Bollinger > > Date: Tue Mar 25 12:55:37 2014 -0500 > > > > serial_core: Fix conditional start_tx on ring buffer not empty > > [Let's try that again. This time without the mess] > > Thanks for the report Aaro. > > Looks like Seth's fix exposes some broken assumptions in the Sun > serial drivers. The same problem is present also on PowerPC G5 Xserve (pmac_zilog driver), and the below type of fix works there too. A. > --- %< --- > From: Peter Hurley > Date: Mon, 9 Jun 2014 19:21:43 -0400 > Subject: [PATCH] serial: sunsab: Test for no tx data on tx restart > > Commit 717f3bbab3c7628736ef738fdbf3d9a28578c26c, > 'serial_core: Fix conditional start_tx on ring buffer not empty' > exposes an incorrect assumption in sunsab's start_tx method; the > tx ring buffer can, in fact, be empty when restarting tx when > performing flow control. > > Test for empty tx ring buffer when in sunsab's start_tx method. > > Signed-off-by: Peter Hurley > --- > drivers/tty/serial/sunsab.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/tty/serial/sunsab.c b/drivers/tty/serial/sunsab.c > index 5faa8e9..b99a4ea 100644 > --- a/drivers/tty/serial/sunsab.c > +++ b/drivers/tty/serial/sunsab.c > @@ -427,6 +427,9 @@ static void sunsab_start_tx(struct uart_port *port) > struct circ_buf *xmit = &up->port.state->xmit; > int i; > > + if (uart_circ_empty(xmit)) > + return; > + > up->interrupt_mask1 &= ~(SAB82532_IMR1_ALLS|SAB82532_IMR1_XPR); > writeb(up->interrupt_mask1, &up->regs->w.imr1); > > -- > 2.0.0 > > -- > To unsubscribe from this list: send the line "unsubscribe sparclinux" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/