From patchwork Mon May 21 22:35:03 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Evan Green X-Patchwork-Id: 10417003 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 4D33E60545 for ; Mon, 21 May 2018 22:35:40 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 380B828AC3 for ; Mon, 21 May 2018 22:35:40 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 2C29528AD0; Mon, 21 May 2018 22:35:40 +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=-7.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, MAILING_LIST_MULTI, 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 C394628AD2 for ; Mon, 21 May 2018 22:35:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752230AbeEUWf0 (ORCPT ); Mon, 21 May 2018 18:35:26 -0400 Received: from mail-pl0-f68.google.com ([209.85.160.68]:33295 "EHLO mail-pl0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752793AbeEUWfY (ORCPT ); Mon, 21 May 2018 18:35:24 -0400 Received: by mail-pl0-f68.google.com with SMTP id n10-v6so9633023plp.0 for ; Mon, 21 May 2018 15:35:23 -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=r3zzRBydPfSXQFERTB0JhnCFJGnse8Z57cAg7VNRcvY=; b=gIm187zZALV0c0HSQL5RFSW8HmE1JBw8kMo10hWeE3RRJksr9mQZtExLpwD085HUkO a6bygE8bMVB9sXr6v08QiNM5gLKgMhhi7QZJUkwWZAJ3tiOiEriOZuZCY1FW6phSg9UY aJlr4jqsa1UZNBtybaQu1aOq7887r8SN8gjO4= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=r3zzRBydPfSXQFERTB0JhnCFJGnse8Z57cAg7VNRcvY=; b=OJB76j78VWUuSG9hIG3eHjecMrVG/8EALc1AhTie5Bn+rB4WkYs8oc0I3PYGiom6mB 5KPbKMH9htTuY+vGSWdoIhyNfl6YMJMtBiXbl69pVfUcgxEP2DJVLPcvKcTmOO8gNYlK rMIZvJVaSrflgwPp2HFhO7nAyJ3ulODkNZXW+P2CcnbJwmNBla8UxDuyzcZGxVHcHNz+ rlKoTMJKa25ld7dxFbJc3D8XPGs6uMLlj+2zD7k/svHNbfrGNP3nR3bufRBO6Co4zEqp GAaTbpX5Y/RCc7c5W4BjLKWgb0N7g2HGdDNwonU2RQXWwOxjvA4U8d6GloX+pelpalFU rLRg== X-Gm-Message-State: ALKqPweGPv/JsVYv1cfCQ/nBWlnyo5JSq9D9LpeatX7Us+HmqiH458Ju 0aGZHpQiP2GeG15EoJJHhWHpFA== X-Google-Smtp-Source: AB8JxZp9W7aMmGZjKCLksdp7DadGF021zhX1jJbnfuzabi11Xc0Mdgzo3dhSyS2Hcwx3MVEr5szFKw== X-Received: by 2002:a17:902:6006:: with SMTP id r6-v6mr21774146plj.70.1526942122587; Mon, 21 May 2018 15:35:22 -0700 (PDT) Received: from evgreen2.mtv.corp.google.com ([2620:0:1000:1511:116f:8bf3:133b:f7fd]) by smtp.gmail.com with ESMTPSA id t14-v6sm28507520pfa.31.2018.05.21.15.35.20 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 21 May 2018 15:35:21 -0700 (PDT) From: Evan Green To: Ulf Hansson , Adrian Hunter , linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org, dianders@chromium.org Cc: Evan Green Subject: [PATCH] mmc: Allow non-sleeping GPIO cd Date: Mon, 21 May 2018 15:35:03 -0700 Message-Id: <20180521223503.152131-1-evgreen@chromium.org> X-Mailer: git-send-email 2.13.5 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 This change uses the appropriate _cansleep or non-sleeping API for reading GPIO card detect state. This allows users with GPIOs that never sleep to avoid a warning when certain quirks are present. The sdhci controller has an SDHCI_QUIRK_NO_CARD_NO_RESET, which indicates that a controller will not reset properly if no card is inserted. With this quirk enabled, mmc_get_cd_gpio is called in several places with a spinlock held and interrupts disabled. gpiod_get_raw_value_cansleep is not happy with this situation, and throws out a warning. For boards that a) use controllers that have this quirk, and b) wire card detect up to a GPIO that doesn't sleep, this is a spurious warning. This change silences that warning, at the cost of pushing this problem down to users that have sleeping GPIOs and controllers with this quirk. Signed-off-by: Evan Green --- This is my initial solution to the warning I was trying to face down in my previous RFC [1]. Upsides of this solution is it manages to avoid the warning in places where the warning doesn't apply, and is low-risk. Other approaches I considered: 1. Changing sdhci_get_cd to reach through mmc and get the GPIO value directly (without sleeping) rather than calling mmc_gpio_get_cd, which uses the cansleep functions. I didn't love this because a) it seemed ugly to be reaching into mmc_host like that and b) I'd have to duplicate the logic in mmc_gpio_get_cd, which seemed brittle. 2. Using mmc_gpio_set_cd_isr to record when the card detect pin changes, and then in sdhci_do_reset we wouldn't actually need to get CD state, just look at the cached value. This seemed risky to me since it would affect all sdhci controllers, and I don't know that everybody using gpio-cd can do interrupts on their pins. 3. Adding mmc_gpio_get_cd_nosleep(). That one's still doable if preferred, but I'd have to give some thought to when sdhci wires up to which one. I'm up for other suggestions. This one most just seemed like the best first stab of minimally addressing the warning without rocking the boat otherwise. [1] https://patchwork.kernel.org/patch/10374633/ --- drivers/mmc/core/slot-gpio.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/drivers/mmc/core/slot-gpio.c b/drivers/mmc/core/slot-gpio.c index 31f7dbb15668..0f497b69f4b8 100644 --- a/drivers/mmc/core/slot-gpio.c +++ b/drivers/mmc/core/slot-gpio.c @@ -75,16 +75,22 @@ EXPORT_SYMBOL(mmc_gpio_get_ro); int mmc_gpio_get_cd(struct mmc_host *host) { + int can_sleep; struct mmc_gpio *ctx = host->slot.handler_priv; if (!ctx || !ctx->cd_gpio) return -ENOSYS; - if (ctx->override_cd_active_level) - return !gpiod_get_raw_value_cansleep(ctx->cd_gpio) ^ - !!(host->caps2 & MMC_CAP2_CD_ACTIVE_HIGH); + can_sleep = gpiod_cansleep(ctx->cd_gpio); + if (ctx->override_cd_active_level) { + int value = can_sleep ? + gpiod_get_raw_value_cansleep(ctx->cd_gpio) : + gpiod_get_raw_value(ctx->cd_gpio); + return !value ^ !!(host->caps2 & MMC_CAP2_CD_ACTIVE_HIGH); + } - return gpiod_get_value_cansleep(ctx->cd_gpio); + return can_sleep ? gpiod_get_value_cansleep(ctx->cd_gpio) : + gpiod_get_value(ctx->cd_gpio); } EXPORT_SYMBOL(mmc_gpio_get_cd);