Re: Looking for an idea/workaround for using MIPS ioremap_nocache (__ioremap) in IRQ

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On 16 February 2015 at 08:35, Rafał Miłecki <zajec5@xxxxxxxxx> wrote:
> Once I've hit
> BUG_ON(in_interrupt());
> when hacking PCI drivers locally on MIPS board. I see the problem but
> don't know the solution.
>
> 1) I think "read" and "write" of struct pci_ops should be safe to call
> in IRQ handler
> 2) In drivers/bcma/driver_pci_host.c we use ioremap_nocache
>
> This causes a problem for boards with 2 PCI(e) cards. The base address
> for the 2nd card is
> #define BCMA_SOC_PCI1_CFG               0x44000000U
> which doesn't allow MIPS to use KSEG1.
>
> As the result forwardtrace looks like this:
> 1) ioremap_nocache
> 2) __ioremap_mode
> 3) __ioremap
> 4) get_vm_area
> 5) __get_vm_area_node
> And then we can hit BUG_ON(in_interrupt());
>
> Can you see any solution for this? Currently there isn't any mainline
> code triggering this problem, but it would be nice to have everything
> working anyway.
>
>
> As one of workarounds I was thinking about mapping whole space early.
> Unfortunately there are many possible registers (0xffff), few PCI
> functions (0x30000), many possible PCI devices (0xf80000). It's way to
> big space I guess to keep it mapped all the time.

Any idea/help about that?

-- 
Rafał





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