From patchwork Tue Jan 31 21:02:28 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Cercueil X-Patchwork-Id: 13123458 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 567D8C636CD for ; Tue, 31 Jan 2023 21:02:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231865AbjAaVCm (ORCPT ); Tue, 31 Jan 2023 16:02:42 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36666 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231527AbjAaVCl (ORCPT ); Tue, 31 Jan 2023 16:02:41 -0500 Received: from aposti.net (aposti.net [89.234.176.197]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 32F6010CA; Tue, 31 Jan 2023 13:02:39 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=crapouillou.net; s=mail; t=1675198956; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:references; bh=4cfcgyV3aGGoH7bkT08YeGcbkBQEHVw7y75FoDFtFug=; b=gmkm7HQaVu5zsURDq0L1yTEtMxxqPBeTqvJRLNLATyCSpS4AsarbmrsmaV3P0993HqzKQP yIB5M2CtpQ3aI+ksGKlfrJAt8yC1p/lA/UH19E95vVLi20MhYyXrJ+HeusdqlO0Xvacv3e pPDjCQbQbLE0yQeGpUGmFykPL2SH1fo= From: Paul Cercueil To: Ulf Hansson Cc: linux-mips@vger.kernel.org, linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org, list@opendingux.net, Paul Cercueil Subject: [PATCH 1/2] mmc: jz4740: Work around bug on JZ4760(B) Date: Tue, 31 Jan 2023 21:02:28 +0000 Message-Id: <20230131210229.68129-1-paul@crapouillou.net> MIME-Version: 1.0 X-Spam: Yes Precedence: bulk List-ID: X-Mailing-List: linux-mmc@vger.kernel.org On JZ4760 and JZ4760B, SD cards fail to run if the maximum clock rate is set to 50 MHz, even though the controller officially does support it. Until the actual bug is found and fixed, limit the maximum clock rate to 24 MHz. Signed-off-by: Paul Cercueil --- drivers/mmc/host/jz4740_mmc.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/mmc/host/jz4740_mmc.c b/drivers/mmc/host/jz4740_mmc.c index 319a2a79c9a0..eb8e9607b086 100644 --- a/drivers/mmc/host/jz4740_mmc.c +++ b/drivers/mmc/host/jz4740_mmc.c @@ -1104,6 +1104,16 @@ static int jz4740_mmc_probe(struct platform_device* pdev) mmc->ops = &jz4740_mmc_ops; if (!mmc->f_max) mmc->f_max = JZ_MMC_CLK_RATE; + + /* + * There seems to be a problem with this driver on the JZ4760 and + * JZ4760B SoCs. There, when using the maximum rate supported (50 MHz), + * the communication fails with many SD cards. + * Until this bug is sorted out, limit the maximum rate to 24 MHz. + */ + if (host->version == JZ_MMC_JZ4760 && mmc->f_max > JZ_MMC_CLK_RATE) + mmc->f_max = JZ_MMC_CLK_RATE; + mmc->f_min = mmc->f_max / 128; mmc->ocr_avail = MMC_VDD_32_33 | MMC_VDD_33_34;