linux-kernel - Re: [PATCH] mmc: Add delay between CMD6 and CMD13 for Sandisk eMMC cards

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Message-ID: <CAL8zT=hs_OoZKn=Emu-aA2h5zpurJTo6NcwbKFZyh1HPxKFWzg@mail.gmail.com>
Date:	Mon, 22 Sep 2014 09:23:09 +0200
From:	Jean-Michel Hautbois <jean-michel.hautbois@...alys.com>
To:	Pavel Machek <pavel@....cz>
Cc:	Jaehoon Chung <jh80.chung@...sung.com>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	"linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
	"tgih.jun@...sung.com" <tgih.jun@...sung.com>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Chris Ball <chris@...ntf.net>
Subject: Re: [PATCH] mmc: Add delay between CMD6 and CMD13 for Sandisk eMMC cards

2014-09-21 19:48 GMT+02:00 Pavel Machek <pavel@....cz>:
> On Mon 2014-09-15 19:44:28, Jaehoon Chung wrote:
>> On 09/15/2014 07:08 PM, Jean-Michel Hautbois wrote:
>> > Hi Jaehoon,
>> >
>> >> On 09/09/2014 09:26 PM, Jean-Michel Hautbois wrote:
>> >>> Tested on a i.MX6 board, with Sandisk SDIN5D1-2G.
>> >>> Without this patch, I/O errors occur.
>> >>> This eMMC seems to have a different Manufacturer ID as it reads 0x45
>> >>> and not 0x2 as specified in datasheet.
>> >>
>> >> I think this patch don't merge into mainline.
>> >> This is not solution for problem.
>> >> you mentioned the below comment, this is workaround.
>> >
>> > Yes
>> >
>> >>>
>> >>> Signed-off-by: Jean-Michel Hautbois <jean-michel.hautbois@...alys.com>
>> >>> ---
>> >>>  drivers/mmc/core/mmc_ops.c | 9 +++++++++
>> >>>  1 file changed, 9 insertions(+)
>> >>>
>> >>> diff --git a/drivers/mmc/core/mmc_ops.c b/drivers/mmc/core/mmc_ops.c
>> >>> index f51b5ba..91babaa 100644
>> >>> --- a/drivers/mmc/core/mmc_ops.c
>> >>> +++ b/drivers/mmc/core/mmc_ops.c
>> >>> @@ -458,6 +458,15 @@ int __mmc_switch(struct mmc_card *card, u8 set, u8 index, u8 value,
>> >>>       if (!use_busy_signal)
>> >>>               return 0;
>> >>>
>> >>> +     /* WORKAROUND: for Sandisk eMMC cards, it might need certain delay
>> >>> +      * before sending CMD13 after CMD6
>> >>> +      * On SDIN5D1-2G MANFID is 0x45 and not 0x2 as specified in datasheet
>> >>> +      */
>> >>> +     if (card->cid.manfid == CID_MANFID_SANDISK ||
>> >>> +             card->cid.manfid == 0x45) {
>> >>> +             msleep(1);
>> >>> +     }
>> >>
>> >> If it's a general problem of Sandisk SDIN5D1-2G,
>> >> I think you need to verify this problem. And can you use the MMC_FIXUP() and QUIRK?
>> >
>> > Well, this is difficult to verify, I know that on all my SDIN5D1-2G I
>> > have this MANFID different from what is defined by CID_MANFID_SANDISK.
>> > How should I use MMC_FIXUP ? Like this ?
>>
>> I think you need to explain why delay is need.
>> i didn't have same card, but it might be your host controller or other problem.
>
> Datasheet says it is needed, so we need to do the delay.
>
> Adding pointer to the datasheet (page, chapter) to the comment might be good idea.

I can't find the page saying a delay must be added... Can you point me
to the correct line ?
BTW, the MANFID is 0x45 on SDIN*-L parts. I will add a comment for this too.

JM
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