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SubjectRe: alpha iommu fixes
On Fri, May 18, 2001 at 09:46:17PM +0400, Ivan Kokshaysky wrote:
> -void
> -cia_pci_tbi(struct pci_controller *hose, dma_addr_t start, dma_addr_t end)
> -{
> - wmb();
> - *(vip)CIA_IOC_PCI_TBIA = 3; /* Flush all locked and unlocked. */
> - mb();
> - *(vip)CIA_IOC_PCI_TBIA;
> -}

I'd rather keep this around. It should be possible to use on CIA2.

> +/* Even if the tbia works, we cannot use it. It effectively locks the
> + * chip (as well as direct write to the tag registers) if there is a
> + * SG DMA operation in progress. This is true at least for PYXIS rev. 1.

Uggg. How did you discover this?

> +/* __save_and_cli(flags); Don't need this -- we're called from
> + pci_unmap_xx() or iommu_arena_alloc()
> + with IPL_MAX after spin_lock_irqsave() */

Just delete it, don't comment it out. You might mention in the
function header comment that we're called with interrupts disabled.

> *(vip)CIA_IOC_CIA_CTRL = ctrl;
> mb();
> - *(vip)CIA_IOC_CIA_CTRL;
> - mb();

I'm pretty sure you don't want to do this. You're risking a
subsequent i/o being posted through the PCI bridge before this
takes effect. An "mb" is only effective inside the CPU.



r~
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