Hi there!
Currently i try to locate a bug in drivers/mmc/host/sdhci.c on
RaspberryPi. I know it is not the mainline kernel...
Currently i use Kernel 3.8.13 and RT Patch 3.8.13-rt12 on the kernel
found at git://github.com/raspberrypi/linux.git on branch rpi-3.8.y.
The bug shows up at booting and after 3 seconds of booting as it wants
to mount the rootfs in a deadlock. as i compiled sdhci_bcm2708 as a
module i can boot the kernel and system as i pushed the system to a usb
stick. As far as good.
Now i try to find the bug, if the rootfs is on the sdcard. I narrowd the
deadlock down to the following lines:
void sdhci_spin_lock_irqsave(struct sdhci_host *host,unsigned long *flags)
{
return;
#ifdef CONFIG_PREEMPT
if(enable_llm)
{
while(sdhci_locked)
{
preempt_schedule();
}
spin_lock_irqsave(&host->lock,*flags);
disable_irq(host->irq);
if(host->second_irq)
disable_irq(host->second_irq);
local_irq_enable();
}
else
#endif
spin_lock_irqsave(&host->lock,*flags);
}
void sdhci_spin_unlock_irqrestore(struct sdhci_host *host,unsigned long
flags)
{
return;
#ifdef CONFIG_PREEMPT
if(enable_llm)
{
local_irq_disable();
if(host->second_irq)
enable_irq(host->second_irq);
enable_irq(host->irq);
}
#endif
spin_unlock_irqrestore(&host->lock,flags);
}
in drivers/mmc/host/sdhci.c . The both return statements are added by
me. Now i can boot the RT Preempt kernel but it is for sure not the
right fix.
My problem is, that i dont know how those both functions should work
with the rt preempt patch.
What can you suggest me to fix that deadlock? I already bought the book
"Linux Kernel Development" but i dont know how the kernel works exaktly
with the PREEMPT patch. Can you point me to a site which shows how
RTPREEMPT works in the irqsave/restore functions or can you please
describe it to me?
Thank you
Georg
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