How-to use the sdio driver?

[Lars Holowko]

Thanks Dongas,

>
>> I am using a Marvell 88W8686 development board. It has a SD-card
style 
>> connector so I would assume that I won't have to modify any
additional 
>> GPIOs because it would use the same GPIOs as a SD-card in the same 
>> slot, right? Pre-plugging the WiFi card does not work (no output
other 
>> then that the libertas driver was registered) - as opposed to the
SD-card.
>
>There should be a line of message similar as follows shown if your SDIO
card is detected and initialized successful.
>mmc0: new SDIO card at address 001
>As Dan said , turning on the MMC core debug option may give you more
useful information.
>(Make sure the console log level is 8 to display all debug messages)

No output for the WiFi card - only for the SD card. 
I looked into mmc_rescan in drivers/mmc/core/core.c - the crucial part
seems to be:

...
		/*
		 * First we search for SDIO...
		 */
		err = mmc_send_io_op_cond(host, 0, &ocr);
		if (!err) {
			if (mmc_attach_sdio(host, ocr))
				mmc_power_off(host);
			goto out;
		}
...

mmc_send_io_op_cond returns with -110(ETIMEOUT) - no matter if I have
the SD card or the WiFi card plugged in.

When I recompile core.c with DEBUG enabled I get this output from the
mmc_send_io_op_cond command.
mmc0: starting CMD5 arg 00000000 flags 000002e1
mmc0: req failed (CMD5): -110, retrying...
mmc0: req failed (CMD5): -110, retrying...
mmc0: req failed (CMD5): -110, retrying...
mmc0: req done (CMD5): -110: 00000000 00000000 00000000 00000000

Whereas the SD card related stuff works fine with the SD card plugged
in:

...
		/*
		 * ...then normal SD...
		 */
		err = mmc_send_app_op_cond(host, 0, &ocr);
		if (!err) {
			if (mmc_attach_sd(host, ocr))
				mmc_power_off(host);
			goto out;
		}
...

mmc0: starting CMD55 arg 00000000 flags 000000f5
VFS: Mounted root (jffs2 filesystem) on device 31:1.
mmc0: req done (CMD55): 0: 00400120 00000000 00000000 00000000
Freeing init memory: 116K
mmc0: starting CMD41 arg 00000000 flags 000000e1
mmc0: req done (CMD41): 0: 00ff8000 00000000 00000000 00000000
mmc_rescan 13=0
mmc_rescan 14
mmc0: clock 375000Hz busmode 1 powermode 2 cs 0 Vdd 20 width 0 timing 0
mmc0: clock 375000Hz busmode 1 powermode 2 cs 1 Vdd 20 width 0 timing 0
mmc0: starting CMD0 arg 00000000 flags 000000c0
mmc0: req done (CMD0): 0: 00ff8000 00000000 00000000 00000000
mmc0: clock 375000Hz busmode 1 powermode 2 cs 0 Vdd 20 width 0 timing 0
mmc0: starting CMD8 arg 000001aa flags 000002f5
mmc0: req done (CMD8): -110: 00ff8000 00000000 00000000 00000000
mmc0: starting CMD55 arg 00000000 flags 000000f5
mmc0: req done (CMD55): 0: 00400120 00000000 00000000 00000000
mmc0: starting CMD41 arg 00300000 flags 000000e1
...

Since the code for mmc_send_app_op_cond and mmc_send_io_op_cond look
very similar, I start to believe that my 2 Wifi boards do not work
propperly in SDIO mode. I will give it another try on a different ARM
board and then switch over to GPIO mode instead.

>> May you point me where this sdio bus scanning/matching is happening? 
>> Is it mmc_rescan in drivers/mmc/core/core.c ?
>The mmc_rescan function will scan the card in slot, for example a SDIO
card,  and then register it into kernel with its function found after a
few basic initialization operations.
>After that, when you insmod libertas module, there's a sdio
>function(wifi) driver registerred into kernel.
>The sdio function and function driver will be matched via some way
predefined for sdio bus.
>Please refer to the sdio_bus_type structure in sdio_bus.c for more
details.

Thanks for clarifying this. I guess until I get something useful from
mmc_rescan, I am stuck...

Thank you so much for your help,

Lars
 
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