[RFC] mmc: core: Set clock before switching to highspeed mode.

[RFC] mmc: core: Set clock before switching to highspeed mode.

[Yousong Zhou]

A SD card with sunxi-mmc can fail with the following error message (RCD for
response CRC error) when trying to switch to highspeed mode.  Setting the bus
clock before the access mode switch fixed it.

    [    1.112060] mmc0: host does not support reading read-only switch, assuming write-enable
    [    1.120203] ehci-platform 1c1c000.usb: irq 31, io mem 0x01c1c000
    [    1.126527] sunxi-mmc 1c0f000.mmc: smc 0 err, cmd 6, RD RCE !!
    [    1.132388] sunxi-mmc 1c0f000.mmc: data error, sending stop command
    [    1.139451] sunxi-mmc 1c0f000.mmc: send stop command failed
    [    1.145056] mmc0: error -110 whilst initialising SD card
    [    1.150424] ehci-platform 1c1c000.usb: USB 2.0 started, EHCI 1.00
    [    1.156533] sunxi-mmc 1c0f000.mmc: smc 0 err, cmd 1, RTO !!

Signed-off-by: Yousong Zhou <yszhou4tech-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 drivers/mmc/core/sd.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
index 4e7366a..402a8db 100644
--- a/drivers/mmc/core/sd.c
+++ b/drivers/mmc/core/sd.c
@@ -366,6 +366,11 @@ int mmc_sd_switch_hs(struct mmc_card *card)
 		return -ENOMEM;
 	}
 
+	/*
+	 * Set bus frequency to match highspeed mode.
+	 */
+	mmc_set_clock(card->host, mmc_sd_get_max_clock(card));
+
 	err = mmc_sd_switch(card, 1, 0, 1, status);
 	if (err)
 		goto out;
@@ -969,11 +974,6 @@ static int mmc_sd_init_card(struct mmc_host *host, u32 ocr,
 			goto free_card;
 
 		/*
-		 * Set bus speed.
-		 */
-		mmc_set_clock(host, mmc_sd_get_max_clock(card));
-
-		/*
 		 * Switch to wider bus (if supported).
 		 */
 		if ((host->caps & MMC_CAP_4_BIT_DATA) &&
-- 
1.7.10.4

Re: [RFC] mmc: core: Set clock before switching to highspeed mode.

[Shawn Lin]

On 2015/9/5 18:19, Yousong Zhou wrote:
> A SD card with sunxi-mmc can fail with the following error message (RCD for
> response CRC error) when trying to switch to highspeed mode.  Setting the bus
> clock before the access mode switch fixed it.

No, that's wrong!

Before this card is switched to highspeed, it works under identification 
mode(From spec: bus clock <= 400KHz). How could you
raise bus clock to higher clk rate which I _guess_ is 52MHz before you 
notify sd cards to run into highspeed mode?

Althought it works for this card, this patch will not please the other 
cards that they might not reply CMDs any longer including the following 
CMD6.


>
>      [    1.112060] mmc0: host does not support reading read-only switch, assuming write-enable
>      [    1.120203] ehci-platform 1c1c000.usb: irq 31, io mem 0x01c1c000
>      [    1.126527] sunxi-mmc 1c0f000.mmc: smc 0 err, cmd 6, RD RCE !!
>      [    1.132388] sunxi-mmc 1c0f000.mmc: data error, sending stop command
>      [    1.139451] sunxi-mmc 1c0f000.mmc: send stop command failed
>      [    1.145056] mmc0: error -110 whilst initialising SD card
>      [    1.150424] ehci-platform 1c1c000.usb: USB 2.0 started, EHCI 1.00
>      [    1.156533] sunxi-mmc 1c0f000.mmc: smc 0 err, cmd 1, RTO !!
>
> Signed-off-by: Yousong Zhou <yszhou4tech-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> ---
>   drivers/mmc/core/sd.c |   10 +++++-----
>   1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
> index 4e7366a..402a8db 100644
> --- a/drivers/mmc/core/sd.c
> +++ b/drivers/mmc/core/sd.c
> @@ -366,6 +366,11 @@ int mmc_sd_switch_hs(struct mmc_card *card)
>   		return -ENOMEM;
>   	}
>
> +	/*
> +	 * Set bus frequency to match highspeed mode.
> +	 */
> +	mmc_set_clock(card->host, mmc_sd_get_max_clock(card));
> +
>   	err = mmc_sd_switch(card, 1, 0, 1, status);
>   	if (err)
>   		goto out;
> @@ -969,11 +974,6 @@ static int mmc_sd_init_card(struct mmc_host *host, u32 ocr,
>   			goto free_card;
>
>   		/*
> -		 * Set bus speed.
> -		 */
> -		mmc_set_clock(host, mmc_sd_get_max_clock(card));
> -
> -		/*
>   		 * Switch to wider bus (if supported).
>   		 */
>   		if ((host->caps & MMC_CAP_4_BIT_DATA) &&
>


-- 
Best Regards
Shawn Lin

Re: [linux-sunxi] Re: [RFC] mmc: core: Set clock before switching to highspeed mode.

[Hans de Goede]

Hi Shawn Lin,

On 05-09-15 16:07, Shawn Lin wrote:
> On 2015/9/5 18:19, Yousong Zhou wrote:
>> A SD card with sunxi-mmc can fail with the following error message (RCD for
>> response CRC error) when trying to switch to highspeed mode.  Setting the bus
>> clock before the access mode switch fixed it.
>
> No, that's wrong!
>
> Before this card is switched to highspeed, it works under identification mode(From spec: bus clock <= 400KHz). How could you
> raise bus clock to higher clk rate which I _guess_ is 52MHz before you notify sd cards to run into highspeed mode?
>
> Althought it works for this card, this patch will not please the other cards that they might not reply CMDs any longer including the following CMD6.

Thanks for the feedback, this is exactly why I asked Yousong Zhou to take this
to the mmc list.

So if this is not the proper fix for the problem that Yousong Zhou is seeing, then
what might be the proper fix ?

Could it be that the sunxi-mmc is doing some things in the wrong order when
changing the clock, or is this all under control of the mmc core ?

Regards,

Hans


>
>
>>
>>      [    1.112060] mmc0: host does not support reading read-only switch, assuming write-enable
>>      [    1.120203] ehci-platform 1c1c000.usb: irq 31, io mem 0x01c1c000
>>      [    1.126527] sunxi-mmc 1c0f000.mmc: smc 0 err, cmd 6, RD RCE !!
>>      [    1.132388] sunxi-mmc 1c0f000.mmc: data error, sending stop command
>>      [    1.139451] sunxi-mmc 1c0f000.mmc: send stop command failed
>>      [    1.145056] mmc0: error -110 whilst initialising SD card
>>      [    1.150424] ehci-platform 1c1c000.usb: USB 2.0 started, EHCI 1.00
>>      [    1.156533] sunxi-mmc 1c0f000.mmc: smc 0 err, cmd 1, RTO !!
>>
>> Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>
>> ---
>>   drivers/mmc/core/sd.c |   10 +++++-----
>>   1 file changed, 5 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
>> index 4e7366a..402a8db 100644
>> --- a/drivers/mmc/core/sd.c
>> +++ b/drivers/mmc/core/sd.c
>> @@ -366,6 +366,11 @@ int mmc_sd_switch_hs(struct mmc_card *card)
>>           return -ENOMEM;
>>       }
>>
>> +    /*
>> +     * Set bus frequency to match highspeed mode.
>> +     */
>> +    mmc_set_clock(card->host, mmc_sd_get_max_clock(card));
>> +
>>       err = mmc_sd_switch(card, 1, 0, 1, status);
>>       if (err)
>>           goto out;
>> @@ -969,11 +974,6 @@ static int mmc_sd_init_card(struct mmc_host *host, u32 ocr,
>>               goto free_card;
>>
>>           /*
>> -         * Set bus speed.
>> -         */
>> -        mmc_set_clock(host, mmc_sd_get_max_clock(card));
>> -
>> -        /*
>>            * Switch to wider bus (if supported).
>>            */
>>           if ((host->caps & MMC_CAP_4_BIT_DATA) &&
>>
>
>

Re: Re: [RFC] mmc: core: Set clock before switching to highspeed mode.

[Shawn Lin]

On 2015/9/5 22:58, Hans de Goede wrote:
> Hi Shawn Lin,
>
> On 05-09-15 16:07, Shawn Lin wrote:
>> On 2015/9/5 18:19, Yousong Zhou wrote:
>>> A SD card with sunxi-mmc can fail with the following error message
>>> (RCD for
>>> response CRC error) when trying to switch to highspeed mode.  Setting
>>> the bus
>>> clock before the access mode switch fixed it.
>>
>> No, that's wrong!
>>
>> Before this card is switched to highspeed, it works under
>> identification mode(From spec: bus clock <= 400KHz). How could you
>> raise bus clock to higher clk rate which I _guess_ is 52MHz before you
>> notify sd cards to run into highspeed mode?
>>
>> Althought it works for this card, this patch will not please the other
>> cards that they might not reply CMDs any longer including the
>> following CMD6.
>
> Thanks for the feedback, this is exactly why I asked Yousong Zhou to
> take this
> to the mmc list.
>
> So if this is not the proper fix for the problem that Yousong Zhou is
> seeing, then
> what might be the proper fix ?
>

 From my knowledge of mmc, there hadn't have a way to deal with this 
"broken" case. In another word, IMO,it's ANTI-SPEC. We can't be too spec 
sometimes, but at least we shouldn't violate it.

> Could it be that the sunxi-mmc is doing some things in the wrong order when
> changing the clock, or is this all under control of the mmc core ?
>

all of this is under control of the mmc core.
So if Yongsong does want this card to work for any linux-based mmc 
stack, I guess something like that should be "better"?

if (switch to HS fail) {
	set_bus_clk
	goto retry switch to HS
}

BUT...I admit it seems strange as well.


> Regards,
>
> Hans
>
>
>>
>>
>>>
>>>      [    1.112060] mmc0: host does not support reading read-only
>>> switch, assuming write-enable
>>>      [    1.120203] ehci-platform 1c1c000.usb: irq 31, io mem 0x01c1c000
>>>      [    1.126527] sunxi-mmc 1c0f000.mmc: smc 0 err, cmd 6, RD RCE !!
>>>      [    1.132388] sunxi-mmc 1c0f000.mmc: data error, sending stop
>>> command
>>>      [    1.139451] sunxi-mmc 1c0f000.mmc: send stop command failed
>>>      [    1.145056] mmc0: error -110 whilst initialising SD card
>>>      [    1.150424] ehci-platform 1c1c000.usb: USB 2.0 started, EHCI
>>> 1.00
>>>      [    1.156533] sunxi-mmc 1c0f000.mmc: smc 0 err, cmd 1, RTO !!
>>>
>>> Signed-off-by: Yousong Zhou <yszhou4tech-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>>> ---
>>>   drivers/mmc/core/sd.c |   10 +++++-----
>>>   1 file changed, 5 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
>>> index 4e7366a..402a8db 100644
>>> --- a/drivers/mmc/core/sd.c
>>> +++ b/drivers/mmc/core/sd.c
>>> @@ -366,6 +366,11 @@ int mmc_sd_switch_hs(struct mmc_card *card)
>>>           return -ENOMEM;
>>>       }
>>>
>>> +    /*
>>> +     * Set bus frequency to match highspeed mode.
>>> +     */
>>> +    mmc_set_clock(card->host, mmc_sd_get_max_clock(card));
>>> +
>>>       err = mmc_sd_switch(card, 1, 0, 1, status);
>>>       if (err)
>>>           goto out;
>>> @@ -969,11 +974,6 @@ static int mmc_sd_init_card(struct mmc_host
>>> *host, u32 ocr,
>>>               goto free_card;
>>>
>>>           /*
>>> -         * Set bus speed.
>>> -         */
>>> -        mmc_set_clock(host, mmc_sd_get_max_clock(card));
>>> -
>>> -        /*
>>>            * Switch to wider bus (if supported).
>>>            */
>>>           if ((host->caps & MMC_CAP_4_BIT_DATA) &&
>>>
>>
>>
>
>
>


-- 
Best Regards
Shawn Lin

Re: [linux-sunxi] Re: [RFC] mmc: core: Set clock before switching to highspeed mode.

[Yousong Zhou]

Hi,

On 6 September 2015 at 08:12, Shawn Lin <shawn.lin@rock-chips.com> wrote:
> On 2015/9/5 22:58, Hans de Goede wrote:
>>
>> Hi Shawn Lin,
>>
>> On 05-09-15 16:07, Shawn Lin wrote:
>>>
>>> On 2015/9/5 18:19, Yousong Zhou wrote:
>>>>
>>>> A SD card with sunxi-mmc can fail with the following error message
>>>> (RCD for
>>>> response CRC error) when trying to switch to highspeed mode.  Setting
>>>> the bus
>>>> clock before the access mode switch fixed it.
>>>
>>>
>>> No, that's wrong!
>>>
>>> Before this card is switched to highspeed, it works under
>>> identification mode(From spec: bus clock <= 400KHz). How could you
>>> raise bus clock to higher clk rate which I _guess_ is 52MHz before you
>>> notify sd cards to run into highspeed mode?
>>>
>>> Althought it works for this card, this patch will not please the other
>>> cards that they might not reply CMDs any longer including the
>>> following CMD6.
>>
>>
>> Thanks for the feedback, this is exactly why I asked Yousong Zhou to
>> take this
>> to the mmc list.
>>
>> So if this is not the proper fix for the problem that Yousong Zhou is
>> seeing, then
>> what might be the proper fix ?
>>
>
> From my knowledge of mmc, there hadn't have a way to deal with this "broken"
> case. In another word, IMO,it's ANTI-SPEC. We can't be too spec sometimes,
> but at least we shouldn't violate it.
>

Maybe the fix is anti-spec.  But the fact is that the card works on
many other platforms with the builtin card reader (not through an USB
adapter), including Mac OS X, my old Nokia Symbian phone, and Windows.

>> Could it be that the sunxi-mmc is doing some things in the wrong order
>> when
>> changing the clock, or is this all under control of the mmc core ?
>>
>
> all of this is under control of the mmc core.
> So if Yongsong does want this card to work for any linux-based mmc stack, I
> guess something like that should be "better"?
>
> if (switch to HS fail) {
>         set_bus_clk
>         goto retry switch to HS
> }
>
> BUT...I admit it seems strange as well.
>

The SD Specification (simplified version) says "If CRC error occurs on
the status data, the host should issue a power cycle.", so I guess the
above approach is anti-spec in some way :)

In case it may help debug this problem, I'd like to add that the card
previously worked fine with U-Boot before commit [1].  This can also
be confirmed by Debian Jessie installer image with which the old
U-Boot there worked fine while the kernel (3.16) did not.

 [1] sunxi: mmc: Properly setup mod-clk and clock sampling phases,
http://git.denx.de/?p=u-boot.git;a=commit;h=fc3a832576ce7bb597b1823935bfb7dcca235c3c

Cheers

                yousong

Re: Re: [RFC] mmc: core: Set clock before switching to highspeed mode.

[Shawn Lin]

在 2015/9/6 20:09, Yousong Zhou 写道:
> Hi,
>
> On 6 September 2015 at 08:12, Shawn Lin <shawn.lin-TNX95d0MmH7DzftRWevZcw@public.gmane.org> wrote:
>> On 2015/9/5 22:58, Hans de Goede wrote:
>>>
>>> Hi Shawn Lin,
>>>
>>> On 05-09-15 16:07, Shawn Lin wrote:
>>>>
>>>> On 2015/9/5 18:19, Yousong Zhou wrote:
>>>>>
>>>>> A SD card with sunxi-mmc can fail with the following error message
>>>>> (RCD for
>>>>> response CRC error) when trying to switch to highspeed mode.  Setting
>>>>> the bus
>>>>> clock before the access mode switch fixed it.
>>>>
>>>>
>>>> No, that's wrong!
>>>>
>>>> Before this card is switched to highspeed, it works under
>>>> identification mode(From spec: bus clock <= 400KHz). How could you
>>>> raise bus clock to higher clk rate which I _guess_ is 52MHz before you
>>>> notify sd cards to run into highspeed mode?
>>>>
>>>> Althought it works for this card, this patch will not please the other
>>>> cards that they might not reply CMDs any longer including the
>>>> following CMD6.
>>>
>>>
>>> Thanks for the feedback, this is exactly why I asked Yousong Zhou to
>>> take this
>>> to the mmc list.
>>>
>>> So if this is not the proper fix for the problem that Yousong Zhou is
>>> seeing, then
>>> what might be the proper fix ?
>>>
>>
>>  From my knowledge of mmc, there hadn't have a way to deal with this "broken"
>> case. In another word, IMO,it's ANTI-SPEC. We can't be too spec sometimes,
>> but at least we shouldn't violate it.
>>
>
> Maybe the fix is anti-spec.  But the fact is that the card works on
> many other platforms with the builtin card reader (not through an USB
> adapter), including Mac OS X, my old Nokia Symbian phone, and Windows.
>
>>> Could it be that the sunxi-mmc is doing some things in the wrong order
>>> when
>>> changing the clock, or is this all under control of the mmc core ?
>>>
>>
>> all of this is under control of the mmc core.
>> So if Yongsong does want this card to work for any linux-based mmc stack, I
>> guess something like that should be "better"?
>>
>> if (switch to HS fail) {
>>          set_bus_clk
>>          goto retry switch to HS
>> }
>>
>> BUT...I admit it seems strange as well.
>>
>
> The SD Specification (simplified version) says "If CRC error occurs on
> the status data, the host should issue a power cycle.", so I guess the
> above approach is anti-spec in some way :)
>

Right，I was guessing that way from your intention.

> In case it may help debug this problem, I'd like to add that the card
> previously worked fine with U-Boot before commit [1].  This can also
> be confirmed by Debian Jessie installer image with which the old
> U-Boot there worked fine while the kernel (3.16) did not.
>
>   [1] sunxi: mmc: Properly setup mod-clk and clock sampling phases,
> http://git.denx.de/?p=u-boot.git;a=commit;h=fc3a832576ce7bb597b1823935bfb7dcca235c3c
>

Interesting... but that at least prove your patch is a workaround but 
not find the root cause.

Anyway, look into commit-sha [1], can you have a test by restoring 
mod-clk and clock sampling phases before jump to kernel.

I happended to fix some problems which seems *similar* to yours(but I'm 
not sure just from commit[1]'s msg):

https://patchwork.kernel.org/patch/7119661/

> Cheers
>
>                  yousong
> --
> To unsubscribe from this list: send the line "unsubscribe linux-mmc" in
> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>
>
>


-- 
Best Regards
Shawn Lin

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Re: Re: [RFC] mmc: core: Set clock before switching to highspeed mode.

[Yousong Zhou]

[-- Attachment #1: Type: text/plain, Size: 5295 bytes --]

On Sep 6, 2015 10:14 PM, "Shawn Lin" <shawn.lin-TNX95d0MmH7DzftRWevZcw@public.gmane.org> wrote:
>
> 在 2015/9/6 20:09, Yousong Zhou 写道:
>>
>> Hi,
>>
>> On 6 September 2015 at 08:12, Shawn Lin <shawn.lin-TNX95d0MmH7DzftRWevZcw@public.gmane.org> wrote:
>>>
>>> On 2015/9/5 22:58, Hans de Goede wrote:
>>>>
>>>>
>>>> Hi Shawn Lin,
>>>>
>>>> On 05-09-15 16:07, Shawn Lin wrote:
>>>>>
>>>>>
>>>>> On 2015/9/5 18:19, Yousong Zhou wrote:
>>>>>>
>>>>>>
>>>>>> A SD card with sunxi-mmc can fail with the following error message
>>>>>> (RCD for
>>>>>> response CRC error) when trying to switch to highspeed mode.  Setting
>>>>>> the bus
>>>>>> clock before the access mode switch fixed it.
>>>>>
>>>>>
>>>>>
>>>>> No, that's wrong!
>>>>>
>>>>> Before this card is switched to highspeed, it works under
>>>>> identification mode(From spec: bus clock <= 400KHz). How could you
>>>>> raise bus clock to higher clk rate which I _guess_ is 52MHz before you
>>>>> notify sd cards to run into highspeed mode?
>>>>>
>>>>> Althought it works for this card, this patch will not please the other
>>>>> cards that they might not reply CMDs any longer including the
>>>>> following CMD6.
>>>>
>>>>
>>>>
>>>> Thanks for the feedback, this is exactly why I asked Yousong Zhou to
>>>> take this
>>>> to the mmc list.
>>>>
>>>> So if this is not the proper fix for the problem that Yousong Zhou is
>>>> seeing, then
>>>> what might be the proper fix ?
>>>>
>>>
>>>  From my knowledge of mmc, there hadn't have a way to deal with this
"broken"
>>> case. In another word, IMO,it's ANTI-SPEC. We can't be too spec
sometimes,
>>> but at least we shouldn't violate it.
>>>
>>
>> Maybe the fix is anti-spec.  But the fact is that the card works on
>> many other platforms with the builtin card reader (not through an USB
>> adapter), including Mac OS X, my old Nokia Symbian phone, and Windows.
>>
>>>> Could it be that the sunxi-mmc is doing some things in the wrong order
>>>> when
>>>> changing the clock, or is this all under control of the mmc core ?
>>>>
>>>
>>> all of this is under control of the mmc core.
>>> So if Yongsong does want this card to work for any linux-based mmc
stack, I
>>> guess something like that should be "better"?
>>>
>>> if (switch to HS fail) {
>>>          set_bus_clk
>>>          goto retry switch to HS
>>> }
>>>
>>> BUT...I admit it seems strange as well.
>>>
>>
>> The SD Specification (simplified version) says "If CRC error occurs on
>> the status data, the host should issue a power cycle.", so I guess the
>> above approach is anti-spec in some way :)
>>
>
> Right，I was guessing that way from your intention.
>
>
>> In case it may help debug this problem, I'd like to add that the card
>> previously worked fine with U-Boot before commit [1].  This can also
>> be confirmed by Debian Jessie installer image with which the old
>> U-Boot there worked fine while the kernel (3.16) did not.
>>
>>   [1] sunxi: mmc: Properly setup mod-clk and clock sampling phases,
>>
http://git.denx.de/?p=u-boot.git;a=commit;h=fc3a832576ce7bb597b1823935bfb7dcca235c3c
>>
>
> Interesting... but that at least prove your patch is a workaround but not
find the root cause.
>
> Anyway, look into commit-sha [1], can you have a test by restoring
mod-clk and clock sampling phases before jump to kernel.
>

Maybe my statement about U-Boot commit [1] above was a little ambiguous,
sorry.  I meant to say that with that commit applied, U-Boot failed
initialising the card the same way as the kernel, i.e. response crc error.

The Debian Jessie installer image's U-Boot worked fine and booted the
kernel because it was before commit [1] happened.  However after that the
3.16 kernel failed initialising the card.

So, with commit [1], U-Boot failed right away without any chance at all
jumping to kernel.

OpenWrt ticket 20387 has more info about the U-Boot failure.

https://dev.openwrt.org/ticket/20387

Anyway, I have no idea what's the effect of those magic numbers on
"sampling phases".  Never played with such things before :)

> I happended to fix some problems which seems *similar* to yours(but I'm
not sure just from commit[1]'s msg):
>
> https://patchwork.kernel.org/patch/7119661/
>
>> Cheers
>>
>>                  yousong
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-mmc" in
>> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>
>>
>>
>
>
> --
> Best Regards
> Shawn Lin
>
> --
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[-- Attachment #2: Type: text/html, Size: 7862 bytes --]

Re: Re: [RFC] mmc: core: Set clock before switching to highspeed mode.

[Hans de Goede]

[-- Attachment #1: Type: text/plain, Size: 5321 bytes --]

Hi,

On 06-09-15 16:47, Yousong Zhou wrote:
> On Sep 6, 2015 10:14 PM, "Shawn Lin" <shawn.lin-TNX95d0MmH7DzftRWevZcw@public.gmane.org> wrote:
>>
>> 在 2015/9/6 20:09, Yousong Zhou 写道:
>>>
>>> Hi,
>>>
>>> On 6 September 2015 at 08:12, Shawn Lin <shawn.lin-TNX95d0MmH7DzftRWevZcw@public.gmane.org> wrote:
>>>>
>>>> On 2015/9/5 22:58, Hans de Goede wrote:
>>>>>
>>>>>
>>>>> Hi Shawn Lin,
>>>>>
>>>>> On 05-09-15 16:07, Shawn Lin wrote:
>>>>>>
>>>>>>
>>>>>> On 2015/9/5 18:19, Yousong Zhou wrote:
>>>>>>>
>>>>>>>
>>>>>>> A SD card with sunxi-mmc can fail with the following error message
>>>>>>> (RCD for
>>>>>>> response CRC error) when trying to switch to highspeed mode.  Setting
>>>>>>> the bus
>>>>>>> clock before the access mode switch fixed it.
>>>>>>
>>>>>>
>>>>>>
>>>>>> No, that's wrong!
>>>>>>
>>>>>> Before this card is switched to highspeed, it works under
>>>>>> identification mode(From spec: bus clock <= 400KHz). How could you
>>>>>> raise bus clock to higher clk rate which I _guess_ is 52MHz before you
>>>>>> notify sd cards to run into highspeed mode?
>>>>>>
>>>>>> Althought it works for this card, this patch will not please the other
>>>>>> cards that they might not reply CMDs any longer including the
>>>>>> following CMD6.
>>>>>
>>>>>
>>>>>
>>>>> Thanks for the feedback, this is exactly why I asked Yousong Zhou to
>>>>> take this
>>>>> to the mmc list.
>>>>>
>>>>> So if this is not the proper fix for the problem that Yousong Zhou is
>>>>> seeing, then
>>>>> what might be the proper fix ?
>>>>>
>>>>
>>>>   From my knowledge of mmc, there hadn't have a way to deal with this
> "broken"
>>>> case. In another word, IMO,it's ANTI-SPEC. We can't be too spec
> sometimes,
>>>> but at least we shouldn't violate it.
>>>>
>>>
>>> Maybe the fix is anti-spec.  But the fact is that the card works on
>>> many other platforms with the builtin card reader (not through an USB
>>> adapter), including Mac OS X, my old Nokia Symbian phone, and Windows.
>>>
>>>>> Could it be that the sunxi-mmc is doing some things in the wrong order
>>>>> when
>>>>> changing the clock, or is this all under control of the mmc core ?
>>>>>
>>>>
>>>> all of this is under control of the mmc core.
>>>> So if Yongsong does want this card to work for any linux-based mmc
> stack, I
>>>> guess something like that should be "better"?
>>>>
>>>> if (switch to HS fail) {
>>>>           set_bus_clk
>>>>           goto retry switch to HS
>>>> }
>>>>
>>>> BUT...I admit it seems strange as well.
>>>>
>>>
>>> The SD Specification (simplified version) says "If CRC error occurs on
>>> the status data, the host should issue a power cycle.", so I guess the
>>> above approach is anti-spec in some way :)
>>>
>>
>> Right，I was guessing that way from your intention.
>>
>>
>>> In case it may help debug this problem, I'd like to add that the card
>>> previously worked fine with U-Boot before commit [1].  This can also
>>> be confirmed by Debian Jessie installer image with which the old
>>> U-Boot there worked fine while the kernel (3.16) did not.
>>>
>>>    [1] sunxi: mmc: Properly setup mod-clk and clock sampling phases,
>>>
> http://git.denx.de/?p=u-boot.git;a=commit;h=fc3a832576ce7bb597b1823935bfb7dcca235c3c

Interesting, one thing that patch does is introduce a switch from parent pll
when switching from 400KHz to higher clocks. Can you try the attached patch ?

If reverting u-boot commit fc3a832576ce7bb597b1823935bfb7dcca235c3c fixes
things, then it is probably best to focus on fixing u-boot first, and then
we can likely apply the same fix to the kernel.

With which SoC(s) are you seeing this problem ? I believe that there
may be some differences between the mmc controller used in the A10/13 vs
later SoCs so this may be a SoC specific issue.

Regards,

Hans


> OpenWrt ticket 20387 has more info about the U-Boot failure.
>
> https://dev.openwrt.org/ticket/20387
>
> Anyway, I have no idea what's the effect of those magic numbers on
> "sampling phases".  Never played with such things before :)
>
>> I happended to fix some problems which seems *similar* to yours(but I'm
> not sure just from commit[1]'s msg):
>>
>> https://patchwork.kernel.org/patch/7119661/
>>
>>> Cheers
>>>
>>>                   yousong
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe linux-mmc" in
>>> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>>
>>>
>>>
>>
>>
>> --
>> Best Regards
>> Shawn Lin
>>
>> --
>> You received this message because you are subscribed to the Google Groups
> "linux-sunxi" group.
>> To unsubscribe from this group and stop receiving emails from it, send an
> email to linux-sunxi+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
>> For more options, visit https://groups.google.com/d/optout.
>

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[-- Attachment #2: 0001-sunxi-mmc-Add-a-delay-after-changing-the-PLL-to-allo.patch --]
[-- Type: text/x-patch, Size: 826 bytes --]

>From 1523e6fbd27b5da22b0c3cb4e8eda50bce7562cf Mon Sep 17 00:00:00 2001
From: Hans de Goede <hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Date: Mon, 7 Sep 2015 08:56:52 +0200
Subject: [PATCH] sunxi: mmc: Add a delay after changing the PLL to allow clock
 to stabilize

Signed-off-by: Hans de Goede <hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
---
 drivers/mmc/sunxi_mmc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/mmc/sunxi_mmc.c b/drivers/mmc/sunxi_mmc.c
index 25f18ad..db3c489 100644
--- a/drivers/mmc/sunxi_mmc.c
+++ b/drivers/mmc/sunxi_mmc.c
@@ -204,6 +204,8 @@ static int mmc_config_clock(struct mmc *mmc)
 	if (mmc_set_mod_clk(mmchost, mmc->clock))
 		return -1;
 
+	mdelay(100);
+
 	/* Clear internal divider */
 	rval &= ~SUNXI_MMC_CLK_DIVIDER_MASK;
 	writel(rval, &mmchost->reg->clkcr);

Re: [linux-sunxi] Re: [RFC] mmc: core: Set clock before switching to highspeed mode.

[Yousong Zhou]

Hi

On 7 September 2015 at 15:02, Hans de Goede <hdegoede@redhat.com> wrote:
> Hi,
>
>
> On 06-09-15 16:47, Yousong Zhou wrote:
>>
>> On Sep 6, 2015 10:14 PM, "Shawn Lin" <shawn.lin@rock-chips.com> wrote:
>>>
>>>
>>> 在 2015/9/6 20:09, Yousong Zhou 写道:
>>>>
>>>>
>>>> Hi,
>>>>
>>>> On 6 September 2015 at 08:12, Shawn Lin <shawn.lin@rock-chips.com>
>>>> wrote:
>>>>>
>>>>>
>>>>> On 2015/9/5 22:58, Hans de Goede wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>> Hi Shawn Lin,
>>>>>>
>>>>>> On 05-09-15 16:07, Shawn Lin wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On 2015/9/5 18:19, Yousong Zhou wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> A SD card with sunxi-mmc can fail with the following error message
>>>>>>>> (RCD for
>>>>>>>> response CRC error) when trying to switch to highspeed mode.
>>>>>>>> Setting
>>>>>>>> the bus
>>>>>>>> clock before the access mode switch fixed it.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> No, that's wrong!
>>>>>>>
>>>>>>> Before this card is switched to highspeed, it works under
>>>>>>> identification mode(From spec: bus clock <= 400KHz). How could you
>>>>>>> raise bus clock to higher clk rate which I _guess_ is 52MHz before
>>>>>>> you
>>>>>>> notify sd cards to run into highspeed mode?
>>>>>>>
>>>>>>> Althought it works for this card, this patch will not please the
>>>>>>> other
>>>>>>> cards that they might not reply CMDs any longer including the
>>>>>>> following CMD6.
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> Thanks for the feedback, this is exactly why I asked Yousong Zhou to
>>>>>> take this
>>>>>> to the mmc list.
>>>>>>
>>>>>> So if this is not the proper fix for the problem that Yousong Zhou is
>>>>>> seeing, then
>>>>>> what might be the proper fix ?
>>>>>>
>>>>>
>>>>>   From my knowledge of mmc, there hadn't have a way to deal with this
>>
>> "broken"
>>>>>
>>>>> case. In another word, IMO,it's ANTI-SPEC. We can't be too spec
>>
>> sometimes,
>>>>>
>>>>> but at least we shouldn't violate it.
>>>>>
>>>>
>>>> Maybe the fix is anti-spec.  But the fact is that the card works on
>>>> many other platforms with the builtin card reader (not through an USB
>>>> adapter), including Mac OS X, my old Nokia Symbian phone, and Windows.
>>>>
>>>>>> Could it be that the sunxi-mmc is doing some things in the wrong order
>>>>>> when
>>>>>> changing the clock, or is this all under control of the mmc core ?
>>>>>>
>>>>>
>>>>> all of this is under control of the mmc core.
>>>>> So if Yongsong does want this card to work for any linux-based mmc
>>
>> stack, I
>>>>>
>>>>> guess something like that should be "better"?
>>>>>
>>>>> if (switch to HS fail) {
>>>>>           set_bus_clk
>>>>>           goto retry switch to HS
>>>>> }
>>>>>
>>>>> BUT...I admit it seems strange as well.
>>>>>
>>>>
>>>> The SD Specification (simplified version) says "If CRC error occurs on
>>>> the status data, the host should issue a power cycle.", so I guess the
>>>> above approach is anti-spec in some way :)
>>>>
>>>
>>> Right，I was guessing that way from your intention.
>>>
>>>
>>>> In case it may help debug this problem, I'd like to add that the card
>>>> previously worked fine with U-Boot before commit [1].  This can also
>>>> be confirmed by Debian Jessie installer image with which the old
>>>> U-Boot there worked fine while the kernel (3.16) did not.
>>>>
>>>>    [1] sunxi: mmc: Properly setup mod-clk and clock sampling phases,
>>>>
>>
>> http://git.denx.de/?p=u-boot.git;a=commit;h=fc3a832576ce7bb597b1823935bfb7dcca235c3c
>
>
> Interesting, one thing that patch does is introduce a switch from parent pll
> when switching from 400KHz to higher clocks. Can you try the attached patch
> ?
>

Previously I tried inserting udelay(1000) immediately after many
writel calls: the result were all the same.  I just tried that patch
adding mdelay(100) after mmc_set_mod_clk(), still no luck, the same
error message just as before.

> If reverting u-boot commit fc3a832576ce7bb597b1823935bfb7dcca235c3c fixes
> things, then it is probably best to focus on fixing u-boot first, and then
> we can likely apply the same fix to the kernel.
>
> With which SoC(s) are you seeing this problem ? I believe that there
> may be some differences between the mmc controller used in the A10/13 vs
> later SoCs so this may be a SoC specific issue.

It's a Cubieboard2 with Allwinner A20.

Regards,

                yousong

>
> Regards,
>
> Hans
>
>
>
>> OpenWrt ticket 20387 has more info about the U-Boot failure.
>>
>> https://dev.openwrt.org/ticket/20387
>>
>> Anyway, I have no idea what's the effect of those magic numbers on
>> "sampling phases".  Never played with such things before :)
>>
>>> I happended to fix some problems which seems *similar* to yours(but I'm
>>
>> not sure just from commit[1]'s msg):
>>>
>>>
>>> https://patchwork.kernel.org/patch/7119661/
>>>
>>>> Cheers
>>>>
>>>>                   yousong
>>>> --
>>>> 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
>>>>
>>>>
>>>>
>>>
>>>
>>> --
>>> Best Regards
>>> Shawn Lin
>>>
>>> --
>>> You received this message because you are subscribed to the Google Groups
>>
>> "linux-sunxi" group.
>>>
>>> To unsubscribe from this group and stop receiving emails from it, send an
>>
>> email to linux-sunxi+unsubscribe@googlegroups.com.
>>>
>>> For more options, visit https://groups.google.com/d/optout.
>>
>>
>

Re: [linux-sunxi] Re: [RFC] mmc: core: Set clock before switching to highspeed mode.

[Yousong Zhou]

[-- Attachment #1: Type: text/plain, Size: 6416 bytes --]

On 7 September 2015 at 15:02, Hans de Goede <hdegoede@redhat.com> wrote:
> Hi,
>
>
> On 06-09-15 16:47, Yousong Zhou wrote:
>>
>> On Sep 6, 2015 10:14 PM, "Shawn Lin" <shawn.lin@rock-chips.com> wrote:
>>>
>>>
>>> 在 2015/9/6 20:09, Yousong Zhou 写道:
>>>>
>>>>
>>>> Hi,
>>>>
>>>> On 6 September 2015 at 08:12, Shawn Lin <shawn.lin@rock-chips.com>
>>>> wrote:
>>>>>
>>>>>
>>>>> On 2015/9/5 22:58, Hans de Goede wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>> Hi Shawn Lin,
>>>>>>
>>>>>> On 05-09-15 16:07, Shawn Lin wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On 2015/9/5 18:19, Yousong Zhou wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> A SD card with sunxi-mmc can fail with the following error message
>>>>>>>> (RCD for
>>>>>>>> response CRC error) when trying to switch to highspeed mode.
>>>>>>>> Setting
>>>>>>>> the bus
>>>>>>>> clock before the access mode switch fixed it.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> No, that's wrong!
>>>>>>>
>>>>>>> Before this card is switched to highspeed, it works under
>>>>>>> identification mode(From spec: bus clock <= 400KHz). How could you
>>>>>>> raise bus clock to higher clk rate which I _guess_ is 52MHz before
>>>>>>> you
>>>>>>> notify sd cards to run into highspeed mode?
>>>>>>>
>>>>>>> Althought it works for this card, this patch will not please the
>>>>>>> other
>>>>>>> cards that they might not reply CMDs any longer including the
>>>>>>> following CMD6.
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> Thanks for the feedback, this is exactly why I asked Yousong Zhou to
>>>>>> take this
>>>>>> to the mmc list.
>>>>>>
>>>>>> So if this is not the proper fix for the problem that Yousong Zhou is
>>>>>> seeing, then
>>>>>> what might be the proper fix ?
>>>>>>
>>>>>
>>>>>   From my knowledge of mmc, there hadn't have a way to deal with this
>>
>> "broken"
>>>>>
>>>>> case. In another word, IMO,it's ANTI-SPEC. We can't be too spec
>>
>> sometimes,
>>>>>
>>>>> but at least we shouldn't violate it.
>>>>>
>>>>
>>>> Maybe the fix is anti-spec.  But the fact is that the card works on
>>>> many other platforms with the builtin card reader (not through an USB
>>>> adapter), including Mac OS X, my old Nokia Symbian phone, and Windows.
>>>>
>>>>>> Could it be that the sunxi-mmc is doing some things in the wrong order
>>>>>> when
>>>>>> changing the clock, or is this all under control of the mmc core ?
>>>>>>
>>>>>
>>>>> all of this is under control of the mmc core.
>>>>> So if Yongsong does want this card to work for any linux-based mmc
>>
>> stack, I
>>>>>
>>>>> guess something like that should be "better"?
>>>>>
>>>>> if (switch to HS fail) {
>>>>>           set_bus_clk
>>>>>           goto retry switch to HS
>>>>> }
>>>>>
>>>>> BUT...I admit it seems strange as well.
>>>>>
>>>>
>>>> The SD Specification (simplified version) says "If CRC error occurs on
>>>> the status data, the host should issue a power cycle.", so I guess the
>>>> above approach is anti-spec in some way :)
>>>>
>>>
>>> Right，I was guessing that way from your intention.
>>>
>>>
>>>> In case it may help debug this problem, I'd like to add that the card
>>>> previously worked fine with U-Boot before commit [1].  This can also
>>>> be confirmed by Debian Jessie installer image with which the old
>>>> U-Boot there worked fine while the kernel (3.16) did not.
>>>>
>>>>    [1] sunxi: mmc: Properly setup mod-clk and clock sampling phases,
>>>>
>>
>> http://git.denx.de/?p=u-boot.git;a=commit;h=fc3a832576ce7bb597b1823935bfb7dcca235c3c
>
>
> Interesting, one thing that patch does is introduce a switch from parent pll
> when switching from 400KHz to higher clocks. Can you try the attached patch
> ?
>
> If reverting u-boot commit fc3a832576ce7bb597b1823935bfb7dcca235c3c fixes
> things, then it is probably best to focus on fixing u-boot first, and then
> we can likely apply the same fix to the kernel.
>

I just tried a method from allwinner's u-boot sources: retry the mode switch in
case of an error [1].  It was accompanied with a comment quoted below:

//retry for Toshiba emmc;for the first time Toshiba emmc change to HS
//it will return response crc err,so retry

Well, that 1GB card of mine is labeled as "pqi" made in Korea.  This workaround
really worked and it succeeded on the second try, though I am not sure how
anti-spec this can be (the spec says a power reset SHOULD be done in the case
of crc error in the status data).

The above change alone can make the card work.  I also noticed that allwinner's
uboot will disable the clock first before setting it and re-enable it
thereafter [2].  I can only guess that this is possibly some bugfix made
by engineers of allwinner.  So I mimicked this approach and attached a patch
here.

 [1] https://github.com/allwinner-zh/bootloader/blob/master/u-boot-2011.09/drivers/mmc/mmc.c#L2220
 [2] https://github.com/allwinner-zh/bootloader/blob/master/u-boot-2011.09/drivers/mmc/sunxi_mmc.c#L822

Regards.

                yousong

> With which SoC(s) are you seeing this problem ? I believe that there
> may be some differences between the mmc controller used in the A10/13 vs
> later SoCs so this may be a SoC specific issue.
>
> Regards,
>
> Hans
>
>
>
>> OpenWrt ticket 20387 has more info about the U-Boot failure.
>>
>> https://dev.openwrt.org/ticket/20387
>>
>> Anyway, I have no idea what's the effect of those magic numbers on
>> "sampling phases".  Never played with such things before :)
>>
>>> I happended to fix some problems which seems *similar* to yours(but I'm
>>
>> not sure just from commit[1]'s msg):
>>>
>>>
>>> https://patchwork.kernel.org/patch/7119661/
>>>
>>>> Cheers
>>>>
>>>>                   yousong
>>>> --
>>>> 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
>>>>
>>>>
>>>>
>>>
>>>
>>> --
>>> Best Regards
>>> Shawn Lin
>>>
>>> --
>>> You received this message because you are subscribed to the Google Groups
>>
>> "linux-sunxi" group.
>>>
>>> To unsubscribe from this group and stop receiving emails from it, send an
>>
>> email to linux-sunxi+unsubscribe@googlegroups.com.
>>>
>>> For more options, visit https://groups.google.com/d/optout.
>>
>>
>

[-- Attachment #2: 0001-mmc-sunxi-split-setting-mod_clk-into-3-steps.patch --]
[-- Type: application/octet-stream, Size: 1406 bytes --]

From 926a68de91619f95399e4621d6b2d57bd0cf91e0 Mon Sep 17 00:00:00 2001
From: Yousong Zhou <yszhou4tech@gmail.com>
Date: Tue, 8 Sep 2015 14:24:58 +0800
Subject: [PATCH 1/2] mmc: sunxi: split setting mod_clk into 3 steps

Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>
---
 drivers/mmc/sunxi_mmc.c |   18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/mmc/sunxi_mmc.c b/drivers/mmc/sunxi_mmc.c
index 25f18ad..e92b4a5 100644
--- a/drivers/mmc/sunxi_mmc.c
+++ b/drivers/mmc/sunxi_mmc.c
@@ -133,14 +133,24 @@ static int mmc_set_mod_clk(struct sunxi_mmc_host *mmchost, unsigned int hz)
 		sclk_dly = 4;
 	}
 
-	writel(CCM_MMC_CTRL_ENABLE | pll | CCM_MMC_CTRL_SCLK_DLY(sclk_dly) |
-	       CCM_MMC_CTRL_N(n) | CCM_MMC_CTRL_OCLK_DLY(oclk_dly) |
-	       CCM_MMC_CTRL_M(div), mmchost->mclkreg);
-
 	debug("mmc %u set mod-clk req %u parent %u n %u m %u rate %u\n",
 	      mmchost->mmc_no, hz, pll_hz, 1u << n, div,
 	      pll_hz / (1u << n) / div);
 
+	/* Disable mclk first */
+	writel(0, mmchost->mclkreg);
+	udelay(500);
+
+	writel(pll | CCM_MMC_CTRL_SCLK_DLY(sclk_dly) | CCM_MMC_CTRL_N(n) |
+	             CCM_MMC_CTRL_OCLK_DLY(oclk_dly) | CCM_MMC_CTRL_M(div),
+	       mmchost->mclkreg);
+	udelay(500);
+
+	/* Re-enable mclk */
+	writel(CCM_MMC_CTRL_ENABLE | readl(mmchost->mclkreg),
+	       mmchost->mclkreg);
+	udelay(500);
+
 	return 0;
 }
 
-- 
1.7.10.4


[-- Attachment #3: 0002-mmc-retry-in-the-case-of-failing-to-switch-to-HS-mod.patch --]
[-- Type: application/octet-stream, Size: 1057 bytes --]

From 4bc6e5f555b317b2d5c3801fe7fb8904183c6157 Mon Sep 17 00:00:00 2001
From: Yousong Zhou <yszhou4tech@gmail.com>
Date: Sun, 30 Aug 2015 15:21:49 +0800
Subject: [PATCH 2/2] mmc: retry in the case of failing to switch to HS mode

Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>
---
 drivers/mmc/mmc.c |   14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
index 371c1ec..7eb9374 100644
--- a/drivers/mmc/mmc.c
+++ b/drivers/mmc/mmc.c
@@ -948,10 +948,18 @@ retry_scr:
 		(mmc->cfg->host_caps & MMC_MODE_HS)))
 		return 0;
 
-	err = sd_switch(mmc, SD_SWITCH_SWITCH, 0, 1, (u8 *)switch_status);
+	timeout = 4;
+	while (true) {
+		err = sd_switch(mmc, SD_SWITCH_SWITCH, 0, 1, (u8 *)switch_status);
+		if (!err)
+			break;
 
-	if (err)
-		return err;
+		timeout -= 1;
+		if (!timeout) {
+			debug("switching to highspeed mode failed: %d\n", err);
+			return err;
+		}
+	}
 
 	if ((__be32_to_cpu(switch_status[4]) & 0x0f000000) == 0x01000000)
 		mmc->card_caps |= MMC_MODE_HS;
-- 
1.7.10.4

Re: Re: [RFC] mmc: core: Set clock before switching to highspeed mode.

[Hans de Goede]

Hi,

On 08-09-15 17:38, Yousong Zhou wrote:
> I just tried a method from allwinner's u-boot sources: retry the mode switch in
> case of an error [1].  It was accompanied with a comment quoted below:
>
> //retry for Toshiba emmc;for the first time Toshiba emmc change to HS
> //it will return response crc err,so retry
>
> Well, that 1GB card of mine is labeled as "pqi" made in Korea.  This workaround
> really worked and it succeeded on the second try, though I am not sure how
> anti-spec this can be (the spec says a power reset SHOULD be done in the case
> of crc error in the status data).
>
> The above change alone can make the card work.  I also noticed that allwinner's
> uboot will disable the clock first before setting it and re-enable it
> thereafter [2].  I can only guess that this is possibly some bugfix made
> by engineers of allwinner.  So I mimicked this approach and attached a patch
> here.

Thanks for this. So if I understand you correctly then just the:

"mmc: retry in the case of failing to switch to HS mode"

Patch is enough to make things work, right ?

That makes sense because the clock dance you are subscribing is something which
allwinner does in many places and it really is not necessary.

Can you do a similar patch for the kernel and test that too ?

And once you've a working kernel patch submit that to Ulf, with the mmc
list in the Cc?

If Ulf is willing to take this fix on the kernel side (I'm the sunxi-mmc maintainer
in the kernel, and the fix will get my ack), then I'm willing to take the u-boot
version of this fix.

Regards,

Hans

Re: [linux-sunxi] Re: [RFC] mmc: core: Set clock before switching to highspeed mode.

[Yousong Zhou]

>>> all of this is under control of the mmc core.
>>> So if Yongsong does want this card to work for any linux-based mmc stack,
>>> I
>>> guess something like that should be "better"?
>>>
>>> if (switch to HS fail) {
>>>          set_bus_clk
>>>          goto retry switch to HS
>>> }
>>>
>>> BUT...I admit it seems strange as well.
>>>
>>
>> The SD Specification (simplified version) says "If CRC error occurs on
>> the status data, the host should issue a power cycle.", so I guess the
>> above approach is anti-spec in some way :)
>>
>
> Right，I was guessing that way from your intention.
>
>> In case it may help debug this problem, I'd like to add that the card
>> previously worked fine with U-Boot before commit [1].  This can also
>> be confirmed by Debian Jessie installer image with which the old
>> U-Boot there worked fine while the kernel (3.16) did not.
>>
>>   [1] sunxi: mmc: Properly setup mod-clk and clock sampling phases,
>>
>> http://git.denx.de/?p=u-boot.git;a=commit;h=fc3a832576ce7bb597b1823935bfb7dcca235c3c
>>
>
> Interesting... but that at least prove your patch is a workaround but not
> find the root cause.
>
> Anyway, look into commit-sha [1], can you have a test by restoring mod-clk
> and clock sampling phases before jump to kernel.
>

Maybe my statement about U-Boot commit [1] above was a little
ambiguous, sorry.  I meant to say that with that commit applied,
U-Boot failed initialising the card the same way as the kernel, i.e.
response crc error.

The Debian Jessie installer image's U-Boot worked fine and booted the
kernel because it was before commit [1] happened.  However after that
the 3.16 kernel failed initialising the card.

So, with commit [1], U-Boot failed right away without any chance at
all jumping to kernel.

OpenWrt ticket 20387 has more info about the U-Boot failure.

https://dev.openwrt.org/ticket/20387

Anyway, I have no idea what's the effect of those magic numbers on
"sampling phases".  Never played with such things before :)

                yousong

> I happended to fix some problems which seems *similar* to yours(but I'm not
> sure just from commit[1]'s msg):
>
> https://patchwork.kernel.org/patch/7119661/

Re: [linux-sunxi] Re: [RFC] mmc: core: Set clock before switching to highspeed mode.

[Shawn Lin]

On 2015/9/6 22:51, Yousong Zhou wrote:
>>>> all of this is under control of the mmc core.
>>>> So if Yongsong does want this card to work for any linux-based mmc stack,
>>>> I
>>>> guess something like that should be "better"?
>>>>
>>>> if (switch to HS fail) {
>>>>           set_bus_clk
>>>>           goto retry switch to HS
>>>> }
>>>>
>>>> BUT...I admit it seems strange as well.
>>>>
>>>
>>> The SD Specification (simplified version) says "If CRC error occurs on
>>> the status data, the host should issue a power cycle.", so I guess the
>>> above approach is anti-spec in some way :)
>>>
>>
>> Right，I was guessing that way from your intention.
>>
>>> In case it may help debug this problem, I'd like to add that the card
>>> previously worked fine with U-Boot before commit [1].  This can also
>>> be confirmed by Debian Jessie installer image with which the old
>>> U-Boot there worked fine while the kernel (3.16) did not.
>>>
>>>    [1] sunxi: mmc: Properly setup mod-clk and clock sampling phases,
>>>
>>> http://git.denx.de/?p=u-boot.git;a=commit;h=fc3a832576ce7bb597b1823935bfb7dcca235c3c
>>>
>>
>> Interesting... but that at least prove your patch is a workaround but not
>> find the root cause.
>>
>> Anyway, look into commit-sha [1], can you have a test by restoring mod-clk
>> and clock sampling phases before jump to kernel.
>>
>
> Maybe my statement about U-Boot commit [1] above was a little
> ambiguous, sorry.  I meant to say that with that commit applied,
> U-Boot failed initialising the card the same way as the kernel, i.e.
> response crc error.
>
> The Debian Jessie installer image's U-Boot worked fine and booted the
> kernel because it was before commit [1] happened.  However after that
> the 3.16 kernel failed initialising the card.
>

So I undertand your point:  Uboot w/o commit[1] + 3.16 kernel failed 
that way just as Uboot w/ commit[1] + pre-3.16 kernel, right?

If that is it, could you check sunxi-platform's patches merged into 
v3.16 for sure whether there is any patch do the same things just like 
what commit[1] did for uboot or not?

> So, with commit [1], U-Boot failed right away without any chance at
> all jumping to kernel.
>
> OpenWrt ticket 20387 has more info about the U-Boot failure.
>
> https://dev.openwrt.org/ticket/20387
>
> Anyway, I have no idea what's the effect of those magic numbers on
> "sampling phases".  Never played with such things before :)
>
>                  yousong
>
>> I happended to fix some problems which seems *similar* to yours(but I'm not
>> sure just from commit[1]'s msg):
>>
>> https://patchwork.kernel.org/patch/7119661/
>
>
>


-- 
Best Regards
Shawn Lin