On Fri, Feb 20, 2009 at 7:49 AM, Tony Lindgren <tony@xxxxxxxxxxx> wrote:
> * Steve Sakoman <sakoman@xxxxxxxxx> [090219 22:38]:
>> Overo has a wifi chip on mmc2 that uses the libertas_sdio driver.
>> I've had my head down working in other areas and failed to noticed
>> that at some point in the 2.6.29 rc cycle SDIO stopped working.
>>
>> I'll start bisecting tomorrow morning, but thought I would ask first
>> to see if anyone else has noticed issues in this area.
>
> I wonder if it happened when we switched to the mainline version of
> omap_hsmmc.c?
>
> Anyways at least now most of the code is in the mainline :) So
> hopefully we can get that fix in too during the -rc cycle.
A quick update . . .
I started adding debug printf's and discovered that the issue seems to
be related to the power supply negotiation code:
mmc_select_voltage: card ocr = 0x00000000
mmc_select_voltage: host ocr_avail = 0x000fe080
mmc1: host doesn't support card's voltages
mmc1: error -22 whilst initialising SDIO card
Seemed strange that the card was returning 0 for ocr, so I added a
printf at the point of the read, and suddenly the card was giving a
reasonable ocr value!
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index df6ce4a..ecde069 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -761,6 +764,7 @@ void mmc_rescan(struct work_struct *work)
* First we search for SDIO...
*/
err = mmc_send_io_op_cond(host, 0, &ocr);
+ pr_warning("mmc_rescan: card ocr from io_op=0x%08x,
err = %d\n", ocr, err);
if (!err) {
if (mmc_attach_sdio(host, ocr))
mmc_power_off(host);
With that printf I now get:
mmc_rescan: card ocr from io_op=0x90ff8000, err = 0
<snip>
mmc1: new SDIO card at address 0001
<snip>
libertas_sdio: Libertas SDIO driver
libertas_sdio: Copyright Pierre Ossman
libertas_sdio mmc1:0001:1: firmware: requesting sd8686_helper.bin
<snip>
libertas_sdio mmc1:0001:1: firmware: requesting sd8686.bin
<snip>
libertas: 00:19:88:05:b5:23, fw 9.70.3p24, cap 0x00000303
eth0 (libertas_sdio): not using net_device_ops yet
<snip>
libertas: PREP_CMD: command 0x00a3 failed: 2
libertas: PREP_CMD: command 0x00a3 failed: 2
libertas: eth0: Marvell WLAN 802.11 adapter
Nice, a completely normal boot! Not quite time to celebrate though --
4 reboots demonstrated a failure to load the libertas firmware 50% of
the time.
To collect more data I tried this code on 4 boards. Two of the 4 act
as described above, the other 2 return 0 for ocr even with the printf.
I rolled back the code to 2.6.28 and again tested all 4 boards.
Result: 100% success with all boards.
These symptoms scream "timing" to me.
As far as I can tell this issue cropped up somewhere around the 2.6.29
rc2->rc3 transition.
Any ideas or words or wisdom? I am far from an expert on the mmc/sdio code.
Steve
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