linux-kernel - Re: [PATCH v2] mmc: dw_mmc: Reset DMA before enabling IDMAC

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAPz6YkWgStHxDJjm0yD4L+qj=1PcB_RQBKVLKLEqLGE8B_smFg@mail.gmail.com>
Date:	Sat, 18 Oct 2014 14:14:49 -0700
From:	Sonny Rao <sonnyrao@...omium.org>
To:	Jaehoon Chung <jh80.chung@...sung.com>
Cc:	Alim Akhtar <alim.akhtar@...il.com>,
	linux-mmc <linux-mmc@...r.kernel.org>,
	Heiko Stuebner <heiko@...ech.de>,
	Seungwon Jeon <tgih.jun@...sung.com>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Douglas Anderson <dianders@...omium.org>,
	Eddie Cai <eddie.cai@...k-chips.com>,
	Addy Ke <addy.ke@...k-chips.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] mmc: dw_mmc: Reset DMA before enabling IDMAC

On Fri, Oct 17, 2014 at 1:26 AM, Jaehoon Chung <jh80.chung@...sung.com> 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 <jh80.chung@...sung.com>
> Tested-by: Jaehoon Chung <jh80.chung@...sung.com>
>
>>
>> Signed-off-by: Sonny Rao <sonnyrao@...omium.org>
>> Signed-off-by: Doug Anderson <dianders@...omium.org>
>> Tested-by: Doug Anderson <dianders@...omium.org>
>> ---
>>  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@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/