Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757362AbaJIWUL (ORCPT ); Thu, 9 Oct 2014 18:20:11 -0400 Received: from mail-yh0-f51.google.com ([209.85.213.51]:57055 "EHLO mail-yh0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751608AbaJIWUJ convert rfc822-to-8bit (ORCPT ); Thu, 9 Oct 2014 18:20:09 -0400 MIME-Version: 1.0 In-Reply-To: References: <1412618020-22278-1-git-send-email-sonnyrao@chromium.org> From: Alim Akhtar Date: Fri, 10 Oct 2014 03:49:28 +0530 Message-ID: Subject: Re: [PATCH] mmc: dw_mmc: Reset DMA before enabling IDMAC To: =?UTF-8?B?RWRkaWUgQ2FpKOiUoeaeqyk=?= Cc: Ulf Hansson , "linux-mmc@vger.kernel.org" , Heiko Stuebner , Sonny Rao , Seungwon Jeon , "linux-kernel@vger.kernel.org" , addy.ke@rock-chips.com, Jaehoon Chung , "linux-arm-kernel@lists.infradead.org" , Douglas Anderson Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Eddie, On Thu, Oct 9, 2014 at 7:43 PM, Eddie Cai(蔡枫) wrote: > Hi Alim > > 2014年10月8日 上午4:28于 "Alim Akhtar" 写道： > > >> >> Hi Sonny/Doug, >> >> On Mon, Oct 6, 2014 at 11:23 PM, 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. >> > >> > Signed-off-by: Sonny Rao >> > Signed-off-by: Doug Anderson >> > --- >> > drivers/mmc/host/dw_mmc.c | 4 ++++ >> > 1 file changed, 4 insertions(+) >> > >> > diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c >> > index 69f0cc6..2b5401e 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 +449,9 @@ 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); >> > + >> Though this is good to do, but this does not look complete to me. >> dw_mmc data book does mention that " It is recommended that the host >> issue reset to DMA interface by setting DMA_RESET bit of the CTRL >> register and then issue a IDMAC software reset." >> The above lines are from 'Transmission and reception with internal >> DMA' section of the data book. >> My suggestion here to add dw_mci_idmac_reset() call after this above >> change. >> >> What is the controller version used in your case? > > it just compatible with dw mmc controler but not the same one. it is > designed by rockchip. > Thats fine, I think every vendor (most of them) has a custom implementation of dw_mmc, but they do have VERID register to check the dw_mmc version. The reason why I asked is, I have seen inconsistency in card enumeration on few controller version, and this patch alone does not help, and adding a call to dw_mci_idmac_reset() after DMA reset is needed. And this is what is recommended in the synopsys's data book also. Do you see any issue/side effect after adding dw_mci_idmac_reset()? >> > /* Select IDMAC interface */ >> > temp = mci_readl(host, CTRL); >> > temp |= SDMMC_CTRL_USE_IDMAC; >> > -- >> > 1.8.3.2 >> > >> > -- >> > To unsubscribe from this list: send the line "unsubscribe linux-mmc" in >> > the body of a message to majordomo@vger.kernel.org >> > More majordomo info at http://vger.kernel.org/majordomo-info.html >> >> >> >> -- >> Regards, >> Alim >> >> -- Regards, Alim -- 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/