raspberry pi mmc issue

DISCUSSION Alexander Aring 3 participants 5 messages Oct 15, 2013 – Oct 16, 2013

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Alexander Aring

author

2013-10-15 11:51 UTC #0 lore raw

Hi all,

I using a not mainlined raspberry pi qemu implementation [1] and tried to run barebox on it. All seems to working but if I probe the mmc with mci0.probe=1 qemu will crash on a assert on 4 byte assert [2].

I dig a little bit into the Datasheet of bcm2835 [3] which says:

"Contrary to Arasan™’s documentation the EMMC module registers can only be accessed as 32 bit registers, i.e. the two LSBs of the address are always zero."

Then I dig into the barebox bcm2835_mci implementation and found something [4]. We use there a readb on SDHCI_RESPONSE_0 which is not a 32 bit access. I just commented the if branch and it works.

Maybe this can make some errors on a real raspberry, too.

Maybe somebody knows a little bit more about mci and can help me to find a proper solution? Perhaps just make a 32 bit access and do some bit magic with masks and shifts?

- Alex

[1] https://github.com/Torlus/qemu-rpi
[2] https://github.com/Torlus/qemu/blob/rpi/hw/arm/bcm2835_emmc.c#L405
[3] http://www.raspberrypi.org/wp-content/uploads/2012/02/BCM2835-ARM-Peripherals.pdf page 66
[4] http://git.pengutronix.de/?p=barebox.git;a=blob;f=drivers/mci/mci-bcm2835.c;h=abd38a35c9bfadcb2e3013eb4b220f74acf7464b;hb=HEAD#l264

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Sascha Hauer

2013-10-15 12:23 UTC #1 lore raw

Quoted 16 lines · Alexander Aring

Hi all,
I using a not mainlined raspberry pi qemu implementation [1] and tried to run barebox on it. All seems to working but if I probe the mmc with mci0.probe=1 qemu will crash on a assert on 4 byte assert [2].
I dig a little bit into the Datasheet of bcm2835 [3] which says:
"Contrary to Arasan™’s documentation the EMMC module registers can only be accessed as 32 bit registers, i.e. the two LSBs of the address are always zero."
Then I dig into the barebox bcm2835_mci implementation and found something [4]. We use there a readb on SDHCI_RESPONSE_0 which is not a 32 bit access. I just commented the if branch and it works.

Quoted 5 lines

Maybe this can make some errors on a real raspberry, too.
Maybe somebody knows a little bit more about mci and can help me to find a proper solution? Perhaps just make a 32 bit access and do some bit magic with masks and shifts?

Here the SD card works (both read and write). I can surely test a patch converting this access into a 32bit access.

The only thing I realize here is that my 3.6.4 kernel fails to access the SD card when barebox has accessed it before:

[    3.623861] mmc0: SD Status: Invalid Allocation Unit size.
[    3.635586] mmc0: error -110 whilst initialising SD card
[    3.724743] mmc0: SD Status: Invalid Allocation Unit size.
[    3.739073] mmc0: error -110 whilst initialising SD card
[    3.836341] mmc0: SD Status: Invalid Allocation Unit size.
[    3.847708] mmc0: error -110 whilst initialising SD card
[    3.965447] mmc0: read SD Status register (SSR) after 3 attempts
[    3.971483] mmc0: SD Status: Invalid Allocation Unit size.

Sascha

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Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

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Alexander Aring

author

2013-10-15 18:31 UTC #2 lore raw

Hi Sascha,

Quoted 17 lines · Sascha Hauer

Quoted 16 lines · Alexander Aring
Hi all,
I using a not mainlined raspberry pi qemu implementation [1] and tried to run barebox on it. All seems to working but if I probe the mmc with mci0.probe=1 qemu will crash on a assert on 4 byte assert [2].
I dig a little bit into the Datasheet of bcm2835 [3] which says:
"Contrary to Arasan™’s documentation the EMMC module registers can only be accessed as 32 bit registers, i.e. the two LSBs of the address are always zero."
Then I dig into the barebox bcm2835_mci implementation and found something [4]. We use there a readb on SDHCI_RESPONSE_0 which is not a 32 bit access. I just commented the if branch and it works.

Quoted 9 lines

Quoted 5 lines
Maybe this can make some errors on a real raspberry, too.
Maybe somebody knows a little bit more about mci and can help me to find a proper solution? Perhaps just make a 32 bit access and do some bit magic with masks and shifts?
Here the SD card works (both read and write). I can surely test a patch converting this access into a 32bit access.

ok I will send a patch which do:

cmd->response[i] |=

	bcm2835_mci_read(
	host,
	SDHCI_RESPONSE_0 +
	(3 - i) * 4 - 1) & 0xFF;

which works for qemu. My workaround (just comment the i != 3 branch) had some trouble to read partition table. But with this solution all works fine.

But I wonder myself why this works now. We readed a byte from this postion but now we read 4 bytes from this position and use the lastest bytes. The correct way should be to make a 24 shift to right. Something like:

cmd->response[i] |=

	bcm2835_mci_read(
	host,
	SDHCI_RESPONSE_0 +
	(3 - i) * 4 - 1) >> 24;

To make a 32 bit access to byte access..

I don't really understand what the code is doing here right now, need some more time to dig into this. Maybe the read overlaps more than one register now which isn't well, too.

Another point is that the for loop (with i != 3) and error handling (every check on ret != -1) looks a little bit crazy for me. Nevertheless I will send a patch soon.

Quoted 11 lines

The only thing I realize here is that my 3.6.4 kernel fails to access the SD card when barebox has accessed it before:

[    3.623861] mmc0: SD Status: Invalid Allocation Unit size.
[    3.635586] mmc0: error -110 whilst initialising SD card
[    3.724743] mmc0: SD Status: Invalid Allocation Unit size.
[    3.739073] mmc0: error -110 whilst initialising SD card
[    3.836341] mmc0: SD Status: Invalid Allocation Unit size.
[    3.847708] mmc0: error -110 whilst initialising SD card
[    3.965447] mmc0: read SD Status register (SSR) after 3 attempts
[    3.971483] mmc0: SD Status: Invalid Allocation Unit size.

Mhh, I think my patch would not fix your problem. I successful access the sdcard after booting linux, but this was on qemu...

- Alex

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Andre Heider

2013-10-15 18:39 UTC #3 lore raw

Hi,

Quoted 15 lines · Alexander Aring

Hi Sascha,

Quoted 11 lines · Sascha Hauer

The only thing I realize here is that my 3.6.4 kernel fails to access the SD card when barebox has accessed it before:

[    3.623861] mmc0: SD Status: Invalid Allocation Unit size.
[    3.635586] mmc0: error -110 whilst initialising SD card
[    3.724743] mmc0: SD Status: Invalid Allocation Unit size.
[    3.739073] mmc0: error -110 whilst initialising SD card
[    3.836341] mmc0: SD Status: Invalid Allocation Unit size.
[    3.847708] mmc0: error -110 whilst initialising SD card
[    3.965447] mmc0: read SD Status register (SSR) after 3 attempts
[    3.971483] mmc0: SD Status: Invalid Allocation Unit size.

Quoted 2 lines

Mhh, I think my patch would not fix your problem. I successful access the sdcard after booting linux, but this was on qemu...

I'm not seeing the issue here either (using Linus' master).

Regards,
Andre

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Sascha Hauer

2013-10-16 07:23 UTC #4 lore raw

Quoted 18 lines · Andre Heider

Hi,

Quoted 15 lines · Alexander Aring

Hi Sascha,

Quoted 11 lines · Sascha Hauer

The only thing I realize here is that my 3.6.4 kernel fails to access the SD card when barebox has accessed it before:

[    3.623861] mmc0: SD Status: Invalid Allocation Unit size.
[    3.635586] mmc0: error -110 whilst initialising SD card
[    3.724743] mmc0: SD Status: Invalid Allocation Unit size.
[    3.739073] mmc0: error -110 whilst initialising SD card
[    3.836341] mmc0: SD Status: Invalid Allocation Unit size.
[    3.847708] mmc0: error -110 whilst initialising SD card
[    3.965447] mmc0: read SD Status register (SSR) after 3 attempts
[    3.971483] mmc0: SD Status: Invalid Allocation Unit size.

Quoted 4 lines

Quoted 2 lines
Mhh, I think my patch would not fix your problem. I successful access the sdcard after booting linux, but this was on qemu...
I'm not seeing the issue here either (using Linus' master).

Oh, great. Then I'll probably just have to update my kernel.

Sascha

Signature · 9 lines

Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

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