From patchwork Mon Apr 23 08:10:30 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Shawn Lin X-Patchwork-Id: 10356377 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 3BFD7601BE for ; Mon, 23 Apr 2018 08:18:27 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 30A682898C for ; Mon, 23 Apr 2018 08:18:27 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 256842898F; Mon, 23 Apr 2018 08:18:27 +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=-6.4 required=2.0 tests=BAYES_00, MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI,RCVD_IN_SORBS_WEB autolearn=ham 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 B4DC528987 for ; Mon, 23 Apr 2018 08:18:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754297AbeDWISZ (ORCPT ); Mon, 23 Apr 2018 04:18:25 -0400 Received: from lucky1.263xmail.com ([211.157.147.130]:33714 "EHLO lucky1.263xmail.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754299AbeDWISW (ORCPT ); Mon, 23 Apr 2018 04:18:22 -0400 Received: from shawn.lin?rock-chips.com (unknown [192.168.167.183]) by lucky1.263xmail.com (Postfix) with ESMTP id 35CDB1F5B4E; Mon, 23 Apr 2018 16:18:17 +0800 (CST) X-263anti-spam: KSV:0; X-MAIL-GRAY: 1 X-MAIL-DELIVERY: 0 X-KSVirus-check: 0 X-ABS-CHECKED: 4 Received: from localhost.localdomain (localhost [127.0.0.1]) by smtp.263.net (Postfix) with ESMTPA id E45ED345; Mon, 23 Apr 2018 16:18:14 +0800 (CST) X-RL-SENDER: shawn.lin@rock-chips.com X-FST-TO: ulf.hansson@linaro.org X-SENDER-IP: 58.22.7.114 X-LOGIN-NAME: shawn.lin@rock-chips.com X-UNIQUE-TAG: X-ATTACHMENT-NUM: 0 X-SENDER: lintao@rock-chips.com X-DNS-TYPE: 0 Received: from unknown (unknown [58.22.7.114]) by smtp.263.net (Postfix) whith SMTP id 18909L89ESQ; Mon, 23 Apr 2018 16:18:17 +0800 (CST) From: Shawn Lin To: Ulf Hansson Cc: Rob Herring , Jaehoon Chung , Wolfram Sang , Adrian Hunter , linux-mmc@vger.kernel.org, devicetree@vger.kernel.org, Shawn Lin Subject: [PATCH v2 2/2] mmc: core: add tunable delay waiting for power to be stable Date: Mon, 23 Apr 2018 16:10:30 +0800 Message-Id: <1524471030-3527-2-git-send-email-shawn.lin@rock-chips.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1524471030-3527-1-git-send-email-shawn.lin@rock-chips.com> References: <1524471030-3527-1-git-send-email-shawn.lin@rock-chips.com> 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 The hard-coded 10ms delay in mmc_power_up came from commit 79bccc5aefb4 ("mmc: increase power up delay"), which said "The TI controller on Toshiba Tecra M5 needs more time to power up or the cards will init incorrectly or not at all." But it's too engineering solution for a special board but force all platforms to wait for that long time, especially painful for mmc_power_up for eMMC when booting. However, it's added since 2009, and we can't tell if other platforms benefit from it. But in practise, the modern hardware are most likely to have a stable power supply with 1ms after setting it for no matter PMIC or discrete power. And more importnatly, most regulators implement the callback of ->set_voltage_time_sel() for regulator core to wait for specific period of time for the power supply to be stable, which means once regulator_set_voltage_* return, the power should reach the the minimum voltage that works for initialization. Of course, if there are some other ways for host to power the card, we should allow them to argue a suitable delay as well. With this patch, we could assign the delay from firmware, or we could assigne it via ->set_ios() callback from host drivers. Signed-off-by: Shawn Lin --- Changes in v2: - allow to assign zero delay from firmware suggested by Adrain drivers/mmc/core/core.c | 4 ++-- drivers/mmc/core/host.c | 4 ++++ include/linux/mmc/host.h | 1 + 3 files changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c index 121ce50..a52e9c2 100644 --- a/drivers/mmc/core/core.c +++ b/drivers/mmc/core/core.c @@ -1658,7 +1658,7 @@ void mmc_power_up(struct mmc_host *host, u32 ocr) * This delay should be sufficient to allow the power supply * to reach the minimum voltage. */ - mmc_delay(10); + mmc_delay(host->ios.power_delay_ms); mmc_pwrseq_post_power_on(host); @@ -1671,7 +1671,7 @@ void mmc_power_up(struct mmc_host *host, u32 ocr) * This delay must be at least 74 clock sizes, or 1 ms, or the * time required to reach a stable voltage. */ - mmc_delay(10); + mmc_delay(host->ios.power_delay_ms); } void mmc_power_off(struct mmc_host *host) diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c index 64b03d6..00ddc15 100644 --- a/drivers/mmc/core/host.c +++ b/drivers/mmc/core/host.c @@ -338,6 +338,9 @@ int mmc_of_parse(struct mmc_host *host) host->dsr_req = 0; } + device_property_read_u32(dev, "power-delay-ms", + &host->ios.power_delay_ms); + return mmc_pwrseq_alloc(host); } @@ -403,6 +406,7 @@ struct mmc_host *mmc_alloc_host(int extra, struct device *dev) host->max_blk_count = PAGE_SIZE / 512; host->fixed_drv_type = -EINVAL; + host->ios.power_delay_ms = 10; return host; } diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h index 7c6eaf6..efa9bab 100644 --- a/include/linux/mmc/host.h +++ b/include/linux/mmc/host.h @@ -22,6 +22,7 @@ struct mmc_ios { unsigned int clock; /* clock rate */ unsigned short vdd; + unsigned int power_delay_ms; /* waiting for stable power */ /* vdd stores the bit number of the selected voltage range from below. */