From nobody Tue Apr 30 12:52:38 2024 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E0161C433EF for ; Thu, 23 Jun 2022 08:00:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231154AbiFWIAQ (ORCPT ); Thu, 23 Jun 2022 04:00:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45228 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229734AbiFWIAP (ORCPT ); Thu, 23 Jun 2022 04:00:15 -0400 Received: from smtp1.axis.com (smtp1.axis.com [195.60.68.17]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9536746CB2; Thu, 23 Jun 2022 01:00:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=axis.com; q=dns/txt; s=axis-central1; t=1655971214; x=1687507214; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=Y6qmbNorIhVgztbdVRKjKcyLbrdYuGj36PW0vcE3Cwc=; b=YHU19ZN/4MSnVcyn1UV3Rshv1q3ntIf6kcvL0ZpBsj1g0LIeEWpdk2Cb qBdDZi04w+a5AhkZR4ghtAkNiJpDGjYMj8v+uycysxsiSWW/cROo/ABg7 q0e93oOtc7ZbIvvhlsYjxGztvJgxTBpMe9ILMAFnukVzeVuQZ7EnEikMY ZjLXaCqWFlMCGwNz6Zwprv0wEXEOqEYFEgPfdm8yh2a3N7XPn1BquJg1G bRGHfgE6FMuAHXFyMYmx9Gz82olgVR2hcTtWV1FRy/N/K2hMDBG23BWPe 0vL/AYV7bd1rgiiuMEQaJaoXKOlHb+3CFsw8Fa+HxcmeUlHBd4CIY7idC A==; From: Vincent Whitchurch To: Ulf Hansson CC: , Vincent Whitchurch , , Subject: [PATCH] mmc: core: Allow speed modes to be adjusted via module param Date: Thu, 23 Jun 2022 10:00:09 +0200 Message-ID: <20220623080009.1775574-1-vincent.whitchurch@axis.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" During board verification, there is a need to test the various supported eMMC/SD speed modes. However, since the framework chooses the best mode supported by the card and the host controller's caps, this currently necessitates changing the devicetree for every iteration. To make changing the modes easier, allow the various host controller capabilities to be cleared via a module parameter. (A per-controller debugfs wouldn't work since the controller needs to be re-probed to trigger re-init of cards. A module parameter is used instead of a global debugfs to allow this to be also set via the kernel command line.) The values to be written are the raw MMC_CAP* values from include/linux/mmc/host.h. This is rather low-level, and these defines are not guaranteed to be stable, but it is perhaps good enough for the indented use case. A warning is emitted when the caps clearing is in effect. Example of use: # grep timing /sys/kernel/debug/mmc0/ios timing spec: 9 (mmc HS200) // MMC_CAP2_HS200_1_8V_SDR # echo $((1 << 5)) > /sys/module/mmc_core/parameters/caps2_clear # echo 16d40000.mmc > /sys/bus/platform/drivers/dwmmc_exynos/unbind # echo 16d40000.mmc > /sys/bus/platform/drivers/dwmmc_exynos/bind # grep timing /sys/kernel/debug/mmc0/ios timing spec: 8 (mmc DDR52) // MMC_CAP_1_8V_DDR # echo $((1 << 12)) > /sys/module/mmc_core/parameters/caps_clear # echo 16d40000.mmc > /sys/bus/platform/drivers/dwmmc_exynos/unbind # echo 16d40000.mmc > /sys/bus/platform/drivers/dwmmc_exynos/bind # grep timing /sys/kernel/debug/mmc0/ios timing spec: 1 (mmc high-speed) # echo 0 > /sys/module/mmc_core/parameters/caps2_clear # echo 16d40000.mmc > /sys/bus/platform/drivers/dwmmc_exynos/unbind # echo 16d40000.mmc > /sys/bus/platform/drivers/dwmmc_exynos/bind # grep timing /sys/kernel/debug/mmc0/ios timing spec: 9 (mmc HS200) Signed-off-by: Vincent Whitchurch --- drivers/mmc/core/host.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c index 2ed2b4d5e5a5..37971b7c7f62 100644 --- a/drivers/mmc/core/host.c +++ b/drivers/mmc/core/host.c @@ -34,6 +34,10 @@ #define cls_dev_to_mmc_host(d) container_of(d, struct mmc_host, class_dev) =20 static DEFINE_IDA(mmc_host_ida); +static unsigned int caps_clear, caps2_clear; + +module_param(caps_clear, uint, 0644); +module_param(caps2_clear, uint, 0644); =20 #ifdef CONFIG_PM_SLEEP static int mmc_host_class_prepare(struct device *dev) @@ -411,6 +415,14 @@ int mmc_of_parse(struct mmc_host *host) host->caps2 &=3D ~(MMC_CAP2_HS400_1_8V | MMC_CAP2_HS400_1_2V | MMC_CAP2_HS400_ES); =20 + if (caps_clear || caps2_clear) + dev_warn(host->parent, + "clearing host controller caps %#x caps2 %#x\n", + caps_clear, caps2_clear); + + host->caps &=3D ~caps_clear; + host->caps2 &=3D ~caps2_clear; + /* Must be after "non-removable" check */ if (device_property_read_u32(dev, "fixed-emmc-driver-type", &drv_type) = =3D=3D 0) { if (host->caps & MMC_CAP_NONREMOVABLE) --=20 2.34.1