3.18-rc2 boot failure on Radxa Rock in dw_mmc

[Max Schwarz]

Hi all,

I'm getting an Oops during boot of 3.18-rc2 on my Radxa Rock. It only happens 
when a microSD card is inserted.

Full boot log: https://gist.github.com/xqms/ff6fc22407e705c9986d
My .config: https://gist.github.com/xqms/9f80f9f9601f85d399cf

The issue seems to be in the dw-mmc driver. It seems that an IRQ is triggered 
before the host->slot[i] pointer is initialized, causing the fault in line
2066 of drivers/mmc/host/dw_mmc.c:

static void dw_mci_work_routine_card(struct work_struct *work)
{
	struct dw_mci *host = container_of(work, struct dw_mci, card_work);
	int i;

	for (i = 0; i < host->num_slots; i++) {
		struct dw_mci_slot *slot = host->slot[i];
		struct mmc_host *mmc = slot->mmc; <-- FAULT
		struct mmc_request *mrq;

A bisect ends at:

commit 51da2240906cb94e8f6ba55e403b6206df6fb2dd
Author: Yuvaraj CD <yuvaraj.cd at gmail.com>
Date:   Fri Aug 22 19:17:50 2014 +0530

    mmc: dw_mmc: use mmc_regulator_get_supply to handle regulators
    
    This patch makes use of mmc_regulator_get_supply() to handle
    the vmmc and vqmmc regulators.Also it moves the code handling
    the these regulators to dw_mci_set_ios().It turned on the vmmc
    and vqmmc during MMC_POWER_UP and MMC_POWER_ON,and turned off
    during MMC_POWER_OFF.
    
    Signed-off-by: Yuvaraj Kumar C D <yuvaraj.cd at samsung.com>
    Signed-off-by: Ulf Hansson <ulf.hansson at linaro.org>

That seems a bit unrelated to me, but maybe it causes a different 
initialization order?

I'm playing around with the initialization order myself, but I haven't managed 
to find a working configuration yet. Can somebody with MMC knowledge find the 
problem or point me into the right direction?

Cheers,
  Max