From patchwork Wed Nov 12 18:14:25 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Frank Rowand X-Patchwork-Id: 5291351 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 9A0BBC11AC for ; Wed, 12 Nov 2014 18:17:44 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 48079201ED for ; Wed, 12 Nov 2014 18:17:43 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id ADB2A201BB for ; Wed, 12 Nov 2014 18:17:37 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1XocRu-0001i4-Dk; Wed, 12 Nov 2014 18:15:22 +0000 Received: from mail-lb0-x233.google.com ([2a00:1450:4010:c04::233]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1XocRT-0008Ud-44 for linux-arm-kernel@lists.infradead.org; Wed, 12 Nov 2014 18:14:57 +0000 Received: by mail-lb0-f179.google.com with SMTP id l4so9874440lbv.10 for ; Wed, 12 Nov 2014 10:14:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=message-id:date:from:reply-to:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding; bh=nSQZ1BT3r0WH3YuNQfB66YMmnSPQHxn9rNuTXsOMAg4=; b=IfTT9cVD1a5sXbG0Hy4/Cndb3guenlamknv7YT7xcGS9npU0vLregl9N/IWjaJKl1m eeK17wJfKacWCFpsBd2j/dYH2xqntg3cE00vVYwbGeuzSftS65s4UDjI+zCKse/yIzLA /htF0lRD4t48ijASyncuI0IAq3aYOlq236nYGqOu3NGjOufsxJyKB8iV7+GFzH3B7pcQ OIPefN2PW5/jSLtL2swp5+Mxcg5mDDqmXQP/yRG72DaubiRiUm+O2DW3rhdIdAW3ULWq /ErfWcYpfxiiwZaspPAXI5UN5qvzg2YGUwVikDS6rpRNftScPqChRv5TclHRSaTlyFGM hGcg== X-Received: by 10.152.37.69 with SMTP id w5mr3160841laj.67.1415816069873; Wed, 12 Nov 2014 10:14:29 -0800 (PST) Received: from [192.168.1.62] (c-67-170-214-152.hsd1.ca.comcast.net. [67.170.214.152]) by mx.google.com with ESMTPSA id l1sm6892478lbd.32.2014.11.12.10.14.26 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 12 Nov 2014 10:14:29 -0800 (PST) Message-ID: <5463A381.9060305@gmail.com> Date: Wed, 12 Nov 2014 10:14:25 -0800 From: Frank Rowand User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20130801 Thunderbird/17.0.8 MIME-Version: 1.0 To: Stephen Boyd Subject: Re: [PATCH] tty: serial: msm_serial: Use DT aliases References: <1414024381-12204-1-git-send-email-sboyd@codeaurora.org> <5461150B.2010907@codeaurora.org> <54616CB3.5000405@gmail.com> <54616F74.5010408@codeaurora.org> <54618077.9000108@gmail.com> In-Reply-To: <54618077.9000108@gmail.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20141112_101455_366170_CB14C3BB X-CRM114-Status: GOOD ( 23.24 ) X-Spam-Score: -0.8 (/) Cc: Arnd Bergmann , Kevin Hilman , Greg Kroah-Hartman , Tyler Baker , lkml , linux-serial@vger.kernel.org, linux-arm-msm , Olof Johansson , "linux-arm-kernel@lists.infradead.org" X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: frowand.list@gmail.com Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-3.0 required=5.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED, FREEMAIL_FROM, RCVD_IN_DNSWL_LOW, RP_MATCHES_RCVD, T_DKIM_INVALID, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP On 11/10/2014 7:20 PM, Frank Rowand wrote: > On 11/10/2014 6:07 PM, Stephen Boyd wrote: >> On 11/10/2014 05:56 PM, Frank Rowand wrote: >>> On 11/10/2014 11:42 AM, Stephen Boyd wrote: >>>> diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c >>>> index 09364dd8cf3a..d1bc6b6cbc70 100644 >>>> --- a/drivers/tty/serial/msm_serial.c >>>> +++ b/drivers/tty/serial/msm_serial.c >>>> @@ -1046,14 +1046,14 @@ static int msm_serial_probe(struct platform_device *pdev) >>>> const struct of_device_id *id; >>>> int irq, line; >>>> >>>> - if (pdev->id == -1) >>>> - pdev->id = atomic_inc_return(&msm_uart_next_id) - 1; >>>> - >>>> if (pdev->dev.of_node) >>>> line = of_alias_get_id(pdev->dev.of_node, "serial"); >>>> else >>>> line = pdev->id; >>>> >>>> + if (line < 0) >>>> + line = atomic_inc_return(&msm_uart_next_id) - 1; >>>> + >>>> if (unlikely(line < 0 || line >= UART_NR)) >>> Then this original check for "line < 0" can also be removed. >>> >>> >> >> Well this matches what was there before. It would do atomic_inc_return >> if the line was negative and then still check for a negative value. I >> don't mind removing it though. Perhaps we should use an ida?: >> > > OK, you are right. If (pdev->id < -1) and (!pdev->dev.of_node) then > the check is still needed. > > You could use an ida. Some drivers use a bit map. I really don't think > this should become a complicated algorithm though. If the rule is that > either all UARTS have an alias, or no UART has an alias, then I think > the patch could be something like the following. > > This combines your original patch, plus your fix patch, plus making > the aliases all or nothing. Not tested, not even compiled. > > What do you think? < snip - previous version of patch > Previous version of the patch did not protect against no alias, followed by alias. From: Frank Rowand This patch is intended to show roughly what an implementation of an all or nothing policy for using serialN aliases would look like. It is intended simply to help determine whether this policy should be used. Combines Stephen's first patch, Stephen's fix patch (to make the serialN alias optional), plus makes use of the serialN alias all or nothing (either all ports have an alias or none do). This is not a correct implementation because the atomic_read(&msm_uart_next_id) does not protect against concurrency; instead a lock should be used. Not tested, not even compiled. Not-Signed-off-by: Frank Rowand Index: linux/drivers/tty/serial/msm_serial.c =================================================================== --- linux.orig/drivers/tty/serial/msm_serial.c +++ linux/drivers/tty/serial/msm_serial.c @@ -1044,17 +1044,31 @@ static int msm_serial_probe(struct platf struct resource *resource; struct uart_port *port; const struct of_device_id *id; - int irq; + int irq, line; + static int no_prev_alias = 1; - if (pdev->id == -1) - pdev->id = atomic_inc_return(&msm_uart_next_id) - 1; + if (pdev->dev.of_node) { + line = of_alias_get_id(pdev->dev.of_node, "serial"); + if (line < 0 && no_prev_alias) { + line = atomic_inc_return(&msm_uart_next_id) - 1; + } else { + no_prev_alias = 0; + if (atomic_read(&msm_uart_next_id)) + line = -ENXIO; + } + } else { + if (pdev->id < 0 && no_prev_alias) + line = atomic_inc_return(&msm_uart_next_id) - 1; + else + line = pdev->id; + } - if (unlikely(pdev->id < 0 || pdev->id >= UART_NR)) + if (unlikely(line < 0 || line >= UART_NR)) return -ENXIO; - dev_info(&pdev->dev, "msm_serial: detected port #%d\n", pdev->id); + dev_info(&pdev->dev, "msm_serial: detected port #%d\n", line); - port = get_port_from_line(pdev->id); + port = get_port_from_line(line); port->dev = &pdev->dev; msm_port = UART_TO_MSM(port);