From patchwork Wed Aug 17 16:09:08 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Douglas Anderson X-Patchwork-Id: 9286109 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id E28ED6086A for ; Wed, 17 Aug 2016 16:11:09 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D50F32967C for ; Wed, 17 Aug 2016 16:11:09 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C9CD62961F; Wed, 17 Aug 2016 16:11:09 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,T_DKIM_INVALID autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 21150295C7 for ; Wed, 17 Aug 2016 16:11:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752703AbcHQQKe (ORCPT ); Wed, 17 Aug 2016 12:10:34 -0400 Received: from mail-pa0-f47.google.com ([209.85.220.47]:34923 "EHLO mail-pa0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751993AbcHQQKb (ORCPT ); Wed, 17 Aug 2016 12:10:31 -0400 Received: by mail-pa0-f47.google.com with SMTP id i5so37659454pat.2 for ; Wed, 17 Aug 2016 09:09:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id; bh=hSenG3bHt3xQvQKgmE5F4IOZ+W4iuVmcgdViwwv95co=; b=Hv4eca5yZVIa4ThPmrbhY7bz3jmHP32Ksa2Q20lgtASFvUeltcNDz/zqK8m0RYMDk5 aksUQgN9I2zPqGPsC7+4ZYI8vHA9JiCl3hAePzsFSQ3MpmprEo10GqJ7XQnaAakYANgs q9BJX0rCRrhMm/RsB4bS6vWfOtQYOwwcR+YSE= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=hSenG3bHt3xQvQKgmE5F4IOZ+W4iuVmcgdViwwv95co=; b=GoYFdjxxzQCj+AAEQExVoP6dqsdkJOPTQId6jUMToXa9NBWh0T94uJdQ6pguJKTbRf OSIWO5L+eRT7FP0nbSldRS8RkHJxfF5CwGnZbbJ4HoX4RlKfXLr0sv0aANBV5453scwU EbaLtfQG+vn3Qrdjj7fRz+Q2yZVSvcwKQXpS48K8lZ1lfZHw4PGz+jn3MHIyf8tO6z1t hUz5s2UKQHOEebc4t3+OFWSvGLnQQ9fVb+j2QZRiPSgioUjRDtXnNIKZtr/01LCuDcJw YnBLWlKmHUkuxH8/EUwoGRxppVjROgp4iMN9k/f02Jgxa5fVkvNICwrLM8usXmYr5Hs5 5NlQ== X-Gm-Message-State: AEkoousY0q58Ua/k4z14aDJWtx9mgGRqmL97q0AIx1mYkFt7jPufrw4QkA/3gbZnp4b+7qR1 X-Received: by 10.66.32.131 with SMTP id j3mr77227771pai.58.1471450186530; Wed, 17 Aug 2016 09:09:46 -0700 (PDT) Received: from chromelab4.mtv.corp.google.com ([100.98.62.8]) by smtp.gmail.com with ESMTPSA id xn11sm48436579pac.38.2016.08.17.09.09.44 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Wed, 17 Aug 2016 09:09:45 -0700 (PDT) From: Douglas Anderson To: adrian.hunter@intel.com, ulf.hansson@linaro.org, Heiko Stuebner , shawn.lin@rock-chips.com Cc: xzy.xu@rock-chips.com, Douglas Anderson , michal.simek@xilinx.com, soren.brinkmann@xilinx.com, linux-arm-kernel@lists.infradead.org, linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] mmc: sdhci-of-arasan: Don't power PHY w/ slow/no clock Date: Wed, 17 Aug 2016 09:09:08 -0700 Message-Id: <1471450148-28307-1-git-send-email-dianders@chromium.org> X-Mailer: git-send-email 2.8.0.rc3.226.g39d4020 Sender: linux-mmc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mmc@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From empirical evidence (tested on Rockchip rk3399), it appears that the PHY intended to be used with the Arasan SDHCI 5.1 controller has trouble turning on when the card clock is slow or off. Strangely these problems appear to show up consistently on some boards while other boares work fine, but on the boards where it shows up the problem reproduces 100% of the time and is quite consistent in its behavior. These problems can be fixed by always making sure that we power on the PHY (and turn on its DLL) when the card clock is faster than about 50 MHz. Once on, we need to make sure that we never power down the PHY / turn off its DLL until the clock is faster again. We'll add logic for handling this into the sdhci-of-arasan driver. Note that right now the only user of a PHY in the sdhci-of-arasan driver is arasan,sdhci-5.1. It's presumed that all arasan,sdhci-5.1 PHY implementations need this workaround, so the logic is only contingent on having a PHY to control. If future Arasan controllers don't have this problem we can add code to decide if we want this flow or not. Also note that we check for slow clocks by checking for <= 400 kHz rather than checking for 50 MHz. This keeps things the most consistent and also means we can power the PHY on at max speed (where the DLL will lock fastest). Presumably anyone who intends to run with a card clock of < 50 MHz and > 400 Khz will be running on a device where this problem is fixed anyway. I believe this brings some resolution to the problems reported before. See the commit 6fc09244d74d ("mmc: sdhci-of-arasan: Revert: Always power the PHY off/on when clock changes"). Signed-off-by: Douglas Anderson Reviewed-by: Shawn Lin Acked-by: Adrian Hunter --- Tested on chromeos kernel-4.4 with backports. drivers/mmc/host/sdhci-of-arasan.c | 61 ++++++++++++++++++++++++++++---------- 1 file changed, 46 insertions(+), 15 deletions(-) diff --git a/drivers/mmc/host/sdhci-of-arasan.c b/drivers/mmc/host/sdhci-of-arasan.c index e0f193f7e3e5..ec2fd00a913d 100644 --- a/drivers/mmc/host/sdhci-of-arasan.c +++ b/drivers/mmc/host/sdhci-of-arasan.c @@ -77,6 +77,7 @@ struct sdhci_arasan_soc_ctl_map { * @host: Pointer to the main SDHCI host structure. * @clk_ahb: Pointer to the AHB clock * @phy: Pointer to the generic phy + * @is_phy_on: True if the PHY is on; false if not. * @sdcardclk_hw: Struct for the clock we might provide to a PHY. * @sdcardclk: Pointer to normal 'struct clock' for sdcardclk_hw. * @soc_ctl_base: Pointer to regmap for syscon for soc_ctl registers. @@ -86,6 +87,7 @@ struct sdhci_arasan_data { struct sdhci_host *host; struct clk *clk_ahb; struct phy *phy; + bool is_phy_on; struct clk_hw sdcardclk_hw; struct clk *sdcardclk; @@ -170,13 +172,47 @@ static void sdhci_arasan_set_clock(struct sdhci_host *host, unsigned int clock) struct sdhci_arasan_data *sdhci_arasan = sdhci_pltfm_priv(pltfm_host); bool ctrl_phy = false; - if (clock > MMC_HIGH_52_MAX_DTR && (!IS_ERR(sdhci_arasan->phy))) - ctrl_phy = true; + if (!IS_ERR(sdhci_arasan->phy)) { + if (!sdhci_arasan->is_phy_on && clock <= 400000) { + /* + * If PHY off, set clock to max speed and power PHY on. + * + * Although PHY docs apparently suggest power cycling + * when changing the clock the PHY doesn't like to be + * powered on while at low speeds like those used in ID + * mode. Even worse is powering the PHY on while the + * clock is off. + * + * To workaround the PHY limitatoins, the best we can + * do is to power it on at a faster speed and then slam + * through low speeds without power cycling. + */ + sdhci_set_clock(host, host->max_clk); + spin_unlock_irq(&host->lock); + phy_power_on(sdhci_arasan->phy); + spin_lock_irq(&host->lock); + sdhci_arasan->is_phy_on = true; + + /* + * We'll now fall through to the below case with + * ctrl_phy = false (so we won't turn off/on). The + * sdhci_set_clock() will set the real clock. + */ + } else if (clock > 400000) { + /* + * At higher clock speeds the PHY is fine being power + * cycled and docs say you _should_ power cycle when + * changing clock speeds. + */ + ctrl_phy = true; + } + } - if (ctrl_phy) { + if (ctrl_phy && sdhci_arasan->is_phy_on) { spin_unlock_irq(&host->lock); phy_power_off(sdhci_arasan->phy); spin_lock_irq(&host->lock); + sdhci_arasan->is_phy_on = false; } sdhci_set_clock(host, clock); @@ -185,6 +221,7 @@ static void sdhci_arasan_set_clock(struct sdhci_host *host, unsigned int clock) spin_unlock_irq(&host->lock); phy_power_on(sdhci_arasan->phy); spin_lock_irq(&host->lock); + sdhci_arasan->is_phy_on = true; } } @@ -239,13 +276,14 @@ static int sdhci_arasan_suspend(struct device *dev) if (ret) return ret; - if (!IS_ERR(sdhci_arasan->phy)) { + if (!IS_ERR(sdhci_arasan->phy) && sdhci_arasan->is_phy_on) { ret = phy_power_off(sdhci_arasan->phy); if (ret) { dev_err(dev, "Cannot power off phy.\n"); sdhci_resume_host(host); return ret; } + sdhci_arasan->is_phy_on = false; } clk_disable(pltfm_host->clk); @@ -281,12 +319,13 @@ static int sdhci_arasan_resume(struct device *dev) return ret; } - if (!IS_ERR(sdhci_arasan->phy)) { + if (!IS_ERR(sdhci_arasan->phy) && host->mmc->actual_clock) { ret = phy_power_on(sdhci_arasan->phy); if (ret) { dev_err(dev, "Cannot power on phy.\n"); return ret; } + sdhci_arasan->is_phy_on = true; } return sdhci_resume_host(host); @@ -547,12 +586,6 @@ static int sdhci_arasan_probe(struct platform_device *pdev) goto unreg_clk; } - ret = phy_power_on(sdhci_arasan->phy); - if (ret < 0) { - dev_err(&pdev->dev, "phy_power_on err.\n"); - goto err_phy_power; - } - host->mmc_host_ops.hs400_enhanced_strobe = sdhci_arasan_hs400_enhanced_strobe; } @@ -565,9 +598,6 @@ static int sdhci_arasan_probe(struct platform_device *pdev) err_add_host: if (!IS_ERR(sdhci_arasan->phy)) - phy_power_off(sdhci_arasan->phy); -err_phy_power: - if (!IS_ERR(sdhci_arasan->phy)) phy_exit(sdhci_arasan->phy); unreg_clk: sdhci_arasan_unregister_sdclk(&pdev->dev); @@ -589,7 +619,8 @@ static int sdhci_arasan_remove(struct platform_device *pdev) struct clk *clk_ahb = sdhci_arasan->clk_ahb; if (!IS_ERR(sdhci_arasan->phy)) { - phy_power_off(sdhci_arasan->phy); + if (sdhci_arasan->is_phy_on) + phy_power_off(sdhci_arasan->phy); phy_exit(sdhci_arasan->phy); }