From patchwork Wed Apr 4 16:45:07 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wolfram Sang X-Patchwork-Id: 10322921 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 909186032A for ; Wed, 4 Apr 2018 16:45:20 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7F5342847D for ; Wed, 4 Apr 2018 16:45:20 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 73BC928C15; Wed, 4 Apr 2018 16:45:20 +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=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI 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 3F4BB288E0 for ; Wed, 4 Apr 2018 16:45:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752358AbeDDQpS (ORCPT ); Wed, 4 Apr 2018 12:45:18 -0400 Received: from sauhun.de ([88.99.104.3]:56738 "EHLO pokefinder.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752016AbeDDQpR (ORCPT ); Wed, 4 Apr 2018 12:45:17 -0400 Received: from localhost (p54B33739.dip0.t-ipconnect.de [84.179.55.57]) by pokefinder.org (Postfix) with ESMTPSA id ECADE2E7604; Wed, 4 Apr 2018 18:45:14 +0200 (CEST) From: Wolfram Sang To: linux-mmc@vger.kernel.org, Yoshihiro Shimoda Cc: linux-renesas-soc@vger.kernel.org, Wolfram Sang Subject: [RFC PATCH] mmc: renesas_sdhi_internal_dmac: limit DMA RX for old SoCs Date: Wed, 4 Apr 2018 18:45:07 +0200 Message-Id: <20180404164507.3394-1-wsa@the-dreams.de> X-Mailer: git-send-email 2.11.0 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 From: Wolfram Sang Early revisions of certain SoCs cannot do multiple DMA RX streams in parallel. To avoid data corruption, only allow one DMA RX channel and fall back to PIO, if needed. Signed-off-by: Wolfram Sang Reviewed-by: Yoshihiro Shimoda Tested-by: Nguyen Viet Dung --- Okay, here is what I came up with to solve this problem. Compared to Shimoda-san's sketch, I replaced the semaphore with atomic bit operations. I think this should do because we really need only a flag telling us if RX is in use already. And bitops should be more lightweight and less complex. I used this test on the target with SD cards in both slots: === #! /bin/sh -e IF="/dev/mmcblk$1p1" PTH="/mnt/mmcblk$1" CHK='/tmp/check' while :; do mkdir -p $PTH mount $IF $PTH &> /dev/null cd $PTH time md5sum -c $CHK >> /tmp/mmc$1 cd umount $PTH done === CHK was manually created beforehand. Before this patch, I got checksum failures within seconds. Now, it runs for hours without checksum problems. Of course, there is a performance regression because of falling back to PIO now, but we can't help that. I also ran the test on a H3 ES2.0 which doesn't suffer from the problem. No regressions, it works out of the box there. Shimoda-san: what do you think of this approach? Please note that I didn't remove the 'revision' from the whitelist yet. This will be done incrementally. I thought to first fix the data corruption issue. Kind regards, Wolfram drivers/mmc/host/renesas_sdhi_internal_dmac.c | 35 ++++++++++++++++++++++++--- 1 file changed, 32 insertions(+), 3 deletions(-) diff --git a/drivers/mmc/host/renesas_sdhi_internal_dmac.c b/drivers/mmc/host/renesas_sdhi_internal_dmac.c index 8e0acd197c43..380570a26a09 100644 --- a/drivers/mmc/host/renesas_sdhi_internal_dmac.c +++ b/drivers/mmc/host/renesas_sdhi_internal_dmac.c @@ -9,6 +9,7 @@ * published by the Free Software Foundation. */ +#include #include #include #include @@ -62,6 +63,17 @@ * need a custom accessor. */ +static unsigned long global_flags = 0; +/* + * Workaround for avoiding to use RX DMAC by multiple channels. + * On R-Car H3 ES1.* and M3-W ES1.0, when multiple SDHI channels use + * RX DMAC simultaneously, sometimes hundreds of bytes data are not + * stored into the system memory even if the DMAC interrupt happened. + * So, this driver then uses one RX DMAC channel only. + */ +#define SDHI_INTERNAL_DMAC_ONE_RX_ONLY 0 +#define SDHI_INTERNAL_DMAC_RX_IN_USE 1 + /* Definitions for sampling clocks */ static struct renesas_sdhi_scc rcar_gen3_scc_taps[] = { { @@ -126,6 +138,10 @@ renesas_sdhi_internal_dmac_abort_dma(struct tmio_mmc_host *host) { renesas_sdhi_internal_dmac_dm_write(host, DM_CM_RST, RST_RESERVED_BITS | val); + + if (host->data && host->data->flags & MMC_DATA_READ) + clear_bit(SDHI_INTERNAL_DMAC_RX_IN_USE, &global_flags); + renesas_sdhi_internal_dmac_enable_dma(host, true); } @@ -155,6 +171,9 @@ renesas_sdhi_internal_dmac_start_dma(struct tmio_mmc_host *host, if (data->flags & MMC_DATA_READ) { dtran_mode |= DTRAN_MODE_CH_NUM_CH1; dir = DMA_FROM_DEVICE; + if (test_bit(SDHI_INTERNAL_DMAC_ONE_RX_ONLY, &global_flags) && + test_and_set_bit(SDHI_INTERNAL_DMAC_RX_IN_USE, &global_flags)) + goto force_pio; } else { dtran_mode |= DTRAN_MODE_CH_NUM_CH0; dir = DMA_TO_DEVICE; @@ -208,6 +227,9 @@ static void renesas_sdhi_internal_dmac_complete_tasklet_fn(unsigned long arg) renesas_sdhi_internal_dmac_enable_dma(host, false); dma_unmap_sg(&host->pdev->dev, host->sg_ptr, host->sg_len, dir); + if (dir == DMA_FROM_DEVICE) + clear_bit(SDHI_INTERNAL_DMAC_RX_IN_USE, &global_flags); + tmio_mmc_do_data_irq(host); out: spin_unlock_irq(&host->lock); @@ -251,18 +273,25 @@ static const struct tmio_mmc_dma_ops renesas_sdhi_internal_dmac_dma_ops = { * implementation as others may use a different implementation. */ static const struct soc_device_attribute gen3_soc_whitelist[] = { - { .soc_id = "r8a7795", .revision = "ES1.*" }, + { .soc_id = "r8a7795", .revision = "ES1.*", + .data = (void *)BIT(SDHI_INTERNAL_DMAC_ONE_RX_ONLY) }, { .soc_id = "r8a7795", .revision = "ES2.0" }, - { .soc_id = "r8a7796", .revision = "ES1.0" }, + { .soc_id = "r8a7796", .revision = "ES1.0", + .data = (void *)BIT(SDHI_INTERNAL_DMAC_ONE_RX_ONLY) }, { .soc_id = "r8a77995", .revision = "ES1.0" }, { /* sentinel */ } }; static int renesas_sdhi_internal_dmac_probe(struct platform_device *pdev) { - if (!soc_device_match(gen3_soc_whitelist)) + const struct soc_device_attribute *soc = soc_device_match(gen3_soc_whitelist); + + if (!soc) return -ENODEV; + if (soc->data) + global_flags |= (unsigned long)soc->data; + return renesas_sdhi_probe(pdev, &renesas_sdhi_internal_dmac_dma_ops); }