From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751285AbVHVW4T (ORCPT ); Mon, 22 Aug 2005 18:56:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751281AbVHVW4S (ORCPT ); Mon, 22 Aug 2005 18:56:18 -0400 Received: from zeus1.kernel.org ([204.152.191.4]:9614 "EHLO zeus1.kernel.org") by vger.kernel.org with ESMTP id S1751292AbVHVW4Q (ORCPT ); Mon, 22 Aug 2005 18:56:16 -0400 Date: Sun, 21 Aug 2005 21:14:26 -0700 From: Nishanth Aravamudan To: Marcelo Tosatti Cc: Nish Aravamudan , Kumar Gala , Andrew Morton , linux-kernel@vger.kernel.org, linuxppc-embedded , vbordug@ru.mvista.com, panto@intracom.gr Subject: Re: [PATCH] cpm_uart: Fix dpram allocation and non-console uarts Message-ID: <20050822041426.GB4554@us.ibm.com> References: <29495f1d0508172242734e1c99@mail.gmail.com> <20050821211235.GD6746@dmt.cnet> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20050821211235.GD6746@dmt.cnet> X-Operating-System: Linux 2.6.12 (i686) User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On 21.08.2005 [18:12:35 -0300], Marcelo Tosatti wrote: > Hi, > > On Wed, Aug 17, 2005 at 10:42:36PM -0700, Nish Aravamudan wrote: > > On 8/8/05, Kumar Gala wrote: > > > (A believe Marcelo would like to see this in 2.6.13, but I'll let him > > > fight over that ;) > > > > > > * Makes dpram allocations work > > > * Makes non-console UART work on both 8xx and 82xx > > > * Fixed whitespace in files that were touched > > > > > > Signed-off-by: Vitaly Bordug > > > Signed-off-by: Pantelis Antoniou > > > Signed-off-by: Kumar Gala > > > > > > --- > > > commit 1de80554bcae877dce3b6d878053eb092ef65c72 > > > tree aba124824607fea1070e86501ddccc9decce362d > > > parent ad81111fd554c9d3c14c0a50885e076af2f9ac9b > > > author Kumar K. Gala Mon, 08 Aug 2005 22:35:39 -0500 > > > committer Kumar K. Gala Mon, 08 Aug 2005 22:35:39 -0500 > > > > > > > > > diff --git a/drivers/serial/cpm_uart/cpm_uart_core.c b/drivers/serial/cpm_uart/cpm_uart_core.c > > > --- a/drivers/serial/cpm_uart/cpm_uart_core.c > > > +++ b/drivers/serial/cpm_uart/cpm_uart_core.c > > > > > > > > > @@ -376,9 +396,19 @@ static int cpm_uart_startup(struct uart_ > > > pinfo->sccp->scc_sccm |= UART_SCCM_RX; > > > } > > > > > > + if (!(pinfo->flags & FLAG_CONSOLE)) > > > + cpm_line_cr_cmd(line,CPM_CR_INIT_TRX); > > > return 0; > > > } > > > > > > +inline void cpm_uart_wait_until_send(struct uart_cpm_port *pinfo) > > > +{ > > > + unsigned long target_jiffies = jiffies + pinfo->wait_closing; > > > + > > > + while (!time_after(jiffies, target_jiffies)) > > > + schedule(); > > > +} > > > > Not sure about that call here. Does the state need to be set so that > > you won't be run again immediately? In any case, I think direct > > schedule() callers are discouraged? Do you want to call a yield() or > > schedule_timeout({0,1}) instead maybe? > > Yep, schedule_timeout(pinfo->wait_closing) looks much better. > > > > /* > > > * Shutdown the uart > > > */ > > > @@ -394,6 +424,12 @@ static void cpm_uart_shutdown(struct uar > > > > > > /* If the port is not the console, disable Rx and Tx. */ > > > if (!(pinfo->flags & FLAG_CONSOLE)) { > > > + /* Wait for all the BDs marked sent */ > > > + while(!cpm_uart_tx_empty(port)) > > > + schedule_timeout(2); > > > > > > > > I think you are using 2 jiffies to guarantee that at least one jiffy > > elapses, which is fine. But, if you do not set the state beforehand, > > schedule_timeout() returns immediately, so you have a busy-wait here. > > Right, what about the following untested patch. > > diff --git a/drivers/serial/cpm_uart/cpm_uart_core.c b/drivers/serial/cpm_uart/cpm_uart_core.c > --- a/drivers/serial/cpm_uart/cpm_uart_core.c > +++ b/drivers/serial/cpm_uart/cpm_uart_core.c > @@ -403,10 +403,9 @@ static int cpm_uart_startup(struct uart_ > > inline void cpm_uart_wait_until_send(struct uart_cpm_port *pinfo) > { > - unsigned long target_jiffies = jiffies + pinfo->wait_closing; > - > - while (!time_after(jiffies, target_jiffies)) > - schedule(); > + set_current_state(TASK_UNINTERRUPTIBLE); > + schedule_timeout(pinfo->wait_closing); > + set_current_state(TASK_RUNNING); > } Both changes look correct/better. Except you shouldn't need to set the state back to TASK_RUNNING in either case, as schedule_timeout() guarantees the task will return in that state. Thanks, Nish