Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751164AbaJRVPM (ORCPT ); Sat, 18 Oct 2014 17:15:12 -0400 Received: from mail-qg0-f43.google.com ([209.85.192.43]:34775 "EHLO mail-qg0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750881AbaJRVPK (ORCPT ); Sat, 18 Oct 2014 17:15:10 -0400 MIME-Version: 1.0 In-Reply-To: <5440D2BF.8070702@samsung.com> References: <1413478686-6857-1-git-send-email-sonnyrao@chromium.org> <5440D2BF.8070702@samsung.com> From: Sonny Rao Date: Sat, 18 Oct 2014 14:14:49 -0700 X-Google-Sender-Auth: S5bcsYT_X_8V4Repk02WWCpQjUw Message-ID: Subject: Re: [PATCH v2] mmc: dw_mmc: Reset DMA before enabling IDMAC To: Jaehoon Chung Cc: Alim Akhtar , linux-mmc , Heiko Stuebner , Seungwon Jeon , Ulf Hansson , Douglas Anderson , Eddie Cai , Addy Ke , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 17, 2014 at 1:26 AM, Jaehoon Chung wrote: > Hi, Sonny. > > On 10/17/2014 01:58 AM, Sonny Rao wrote: >> We've already got a reset of DMA after it's done. Add one before we >> start DMA too. This fixes a data corruption on Rockchip SoCs which >> will get bad data when doing a DMA transfer after doing a PIO transfer. >> >> We tested this on an Exynos 5800 with HS200 and didn't notice any >> difference in sequential read throughput. > > Didn't affect the write throughput? Write is usually much slower than read, but I went ahead and re-tested and saw no difference on writes. > I tested this on exynos3/4 with DDR50 and HS200. > > Acked-by: Jaehoon Chung > Tested-by: Jaehoon Chung > >> >> Signed-off-by: Sonny Rao >> Signed-off-by: Doug Anderson >> Tested-by: Doug Anderson >> --- >> drivers/mmc/host/dw_mmc.c | 5 +++++ >> 1 file changed, 5 insertions(+) >> >> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c >> index 69f0cc6..ca67f69 100644 >> --- a/drivers/mmc/host/dw_mmc.c >> +++ b/drivers/mmc/host/dw_mmc.c >> @@ -83,6 +83,7 @@ struct idmac_desc { >> #endif /* CONFIG_MMC_DW_IDMAC */ >> >> static bool dw_mci_reset(struct dw_mci *host); >> +static bool dw_mci_ctrl_reset(struct dw_mci *host, u32 reset); >> >> #if defined(CONFIG_DEBUG_FS) >> static int dw_mci_req_show(struct seq_file *s, void *v) >> @@ -448,6 +449,10 @@ static void dw_mci_idmac_start_dma(struct dw_mci *host, unsigned int sg_len) >> >> dw_mci_translate_sglist(host, host->data, sg_len); >> >> + /* Make sure to reset DMA in case we did PIO before this */ >> + dw_mci_ctrl_reset(host, SDMMC_CTRL_DMA_RESET); >> + dw_mci_idmac_reset(host); >> + >> /* Select IDMAC interface */ >> temp = mci_readl(host, CTRL); >> temp |= SDMMC_CTRL_USE_IDMAC; >> > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/