From patchwork Mon Sep 13 18:07:28 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Cyril Chemparathy X-Patchwork-Id: 175192 X-Patchwork-Delegate: khilman@deeprootsystems.com Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by demeter1.kernel.org (8.14.4/8.14.3) with ESMTP id o8DI8MEx031630 for ; Mon, 13 Sep 2010 18:08:25 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754620Ab0IMSIJ (ORCPT ); Mon, 13 Sep 2010 14:08:09 -0400 Received: from devils.ext.ti.com ([198.47.26.153]:39562 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754663Ab0IMSHj (ORCPT ); Mon, 13 Sep 2010 14:07:39 -0400 Received: from dlep36.itg.ti.com ([157.170.170.91]) by devils.ext.ti.com (8.13.7/8.13.7) with ESMTP id o8DI7cBw009009 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Mon, 13 Sep 2010 13:07:38 -0500 Received: from legion.dal.design.ti.com (localhost [127.0.0.1]) by dlep36.itg.ti.com (8.13.8/8.13.8) with ESMTP id o8DI7aXO003406; Mon, 13 Sep 2010 13:07:37 -0500 (CDT) Received: from gtrgwdeb (gtrgwdeb.telogy.design.ti.com [158.218.102.24]) by legion.dal.design.ti.com (8.11.7p1+Sun/8.11.7) with ESMTP id o8DI7af19360; Mon, 13 Sep 2010 13:07:36 -0500 (CDT) Received: by gtrgwdeb (Postfix, from userid 39959) id 7CF7E1E7989; Mon, 13 Sep 2010 14:07:34 -0400 (EDT) From: Cyril Chemparathy To: netdev@vger.kernel.org, davinci-linux-open-source@linux.davincidsp.com, linux-omap@vger.kernel.org Cc: michael.williamson@criticallink.com, caglarakyuz@gmail.com, bparrot@ti.com, Cyril Chemparathy Subject: [PATCH 6/9] net: davinci_mdio: use calculated bus access times Date: Mon, 13 Sep 2010 14:07:28 -0400 Message-Id: <1284401251-8846-7-git-send-email-cyril@ti.com> X-Mailer: git-send-email 1.7.0.4 In-Reply-To: <1284401251-8846-1-git-send-email-cyril@ti.com> References: <1284401251-8846-1-git-send-email-cyril@ti.com> Sender: linux-omap-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-omap@vger.kernel.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.3 (demeter1.kernel.org [140.211.167.41]); Mon, 13 Sep 2010 18:08:25 +0000 (UTC) diff --git a/drivers/net/davinci_mdio.c b/drivers/net/davinci_mdio.c index a9fbc26..f2d7639 100644 --- a/drivers/net/davinci_mdio.c +++ b/drivers/net/davinci_mdio.c @@ -83,11 +83,12 @@ struct davinci_mdio_data { struct device *dev; struct mii_bus *bus; bool suspended; + unsigned long access_time; /* jiffies */ }; static void __davinci_mdio_reset(struct davinci_mdio_data *data) { - u32 mdio_in, div; + u32 mdio_in, div, mdio_out_khz, access_time; mdio_in = clk_get_rate(data->clk); div = (mdio_in / data->pdata.bus_freq) - 1; @@ -96,6 +97,25 @@ static void __davinci_mdio_reset(struct davinci_mdio_data *data) /* set enable and clock divider */ __raw_writel(div | CONTROL_ENABLE, &data->regs->control); + + /* + * One mdio transaction consists of: + * 32 bits of preamble + * 32 bits of transferred data + * 24 bits of bus yield (not needed unless shared?) + */ + mdio_out_khz = mdio_in / (1000 * (div + 1)); + access_time = (88 * 1000) / mdio_out_khz; + + /* + * In the worst case, we could be kicking off a user-access immediately + * after the mdio bus scan state-machine triggered its own read. If + * so, our request could get deferred by one access cycle. We + * defensively allow for 4 access cycles. + */ + data->access_time = usecs_to_jiffies(access_time * 4); + if (!data->access_time) + data->access_time = 1; } static int davinci_mdio_reset(struct mii_bus *bus) @@ -105,15 +125,8 @@ static int davinci_mdio_reset(struct mii_bus *bus) __davinci_mdio_reset(data); - /* - * wait for scan logic to settle: - * the scan time consists of (a) a large fixed component, and (b) a - * small component that varies with the mii bus frequency. These - * were estimated using measurements at 1.1 and 2.2 MHz on tnetv107x - * silicon. Since the effect of (b) was found to be largely - * negligible, we keep things simple here. - */ - mdelay(1); + /* wait for scan logic to settle */ + msleep(PHY_MAX_ADDR * data->access_time); /* dump hardware version info */ ver = __raw_readl(&data->regs->version);