From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AE1A5C432BE for ; Thu, 29 Jul 2021 07:29:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9B0BF61057 for ; Thu, 29 Jul 2021 07:29:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234703AbhG2H3s (ORCPT ); Thu, 29 Jul 2021 03:29:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45124 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234524AbhG2H3n (ORCPT ); Thu, 29 Jul 2021 03:29:43 -0400 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2E4BEC0613CF for ; Thu, 29 Jul 2021 00:29:41 -0700 (PDT) Received: from drehscheibe.grey.stw.pengutronix.de ([2a0a:edc0:0:c01:1d::a2]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1m90U7-0000u9-F0; Thu, 29 Jul 2021 09:29:39 +0200 Received: from [2a0a:edc0:0:900:2e4d:54ff:fe67:bfa5] (helo=ginster) by drehscheibe.grey.stw.pengutronix.de with esmtp (Exim 4.92) (envelope-from ) id 1m90U6-0002J0-Fl; Thu, 29 Jul 2021 09:29:38 +0200 Received: from jbe by ginster with local (Exim 4.92) (envelope-from ) id 1m90U6-0002gl-Ej; Thu, 29 Jul 2021 09:29:38 +0200 From: Juergen Borleis To: linux-mmc@vger.kernel.org Cc: linux-kernel@vger.kernel.org, festevam@gmail.com, wsa+renesas@sang-engineering.com, dianders@chromium.org, ulf.hansson@linaro.org, kernel@pengutronix.de Subject: [PATCH 2/2] mmc: mxcmmc: don't expect a DMA operation if DMA seems present Date: Thu, 29 Jul 2021 09:29:29 +0200 Message-Id: <20210729072929.10267-3-jbe@pengutronix.de> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20210729072929.10267-1-jbe@pengutronix.de> References: <20210729072929.10267-1-jbe@pengutronix.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 2a0a:edc0:0:c01:1d::a2 X-SA-Exim-Mail-From: jbe@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Change the driver's default behaviour from DMA to PIO for each request. Preparing DMA can fail or be prevented by other causes. Switch to a DMA operation only, if it is really possible. This avoids a NULL pointer dereference on shutdown in mxcmci_start_cmd() where it tries to store a DMA callback configuration into mxcmci_host::desc which isn't setup a this point of time. Signed-off-by: Juergen Borleis --- drivers/mmc/host/mxcmmc.c | 24 ++++++++++++++---------- 1 file changed, 14 insertions(+), 10 deletions(-) diff --git a/drivers/mmc/host/mxcmmc.c b/drivers/mmc/host/mxcmmc.c index 611f827..41feea9 100644 --- a/drivers/mmc/host/mxcmmc.c +++ b/drivers/mmc/host/mxcmmc.c @@ -293,14 +293,13 @@ static int mxcmci_setup_data(struct mxcmci_host *host, struct mmc_data *data) mxcmci_writew(host, blksz, MMC_REG_BLK_LEN); host->datasize = datasize; - if (!mxcmci_use_dma(host)) - return 0; + if (host->dma == NULL) + return 0; /* Keep PIO */ + /* Avoid the use of DMA on short transfers, e.g. non-sectors for example */ for_each_sg(data->sg, sg, data->sg_len, i) { - if (sg->offset & 3 || sg->length & 3 || sg->length < 512) { - host->do_dma = 0; - return 0; - } + if (sg->offset & 3 || sg->length & 3 || sg->length < 512) + return 0; /* Keep PIO */ } if (data->flags & MMC_DATA_READ) { @@ -325,9 +324,11 @@ static int mxcmci_setup_data(struct mxcmci_host *host, struct mmc_data *data) if (!host->desc) { dma_unmap_sg(host->dma->device->dev, data->sg, data->sg_len, host->dma_dir); - host->do_dma = 0; - return 0; /* Fall back to PIO */ + return 0; /* Keep PIO */ } + + /* DMA is possible */ + host->do_dma = 1; wmb(); dmaengine_submit(host->desc); @@ -747,8 +748,11 @@ static void mxcmci_request(struct mmc_host *mmc, struct mmc_request *req) host->req = req; host->cmdat &= ~CMD_DAT_CONT_INIT; - if (host->dma) - host->do_dma = 1; + /* + * Default always to PIO. DMA will be enabled in + * mxcmci_setup_data() if possible + */ + host->do_dma = 0; if (req->data) { error = mxcmci_setup_data(host, req->data); -- 2.20.1