Hi. On Mon, Sep 26, 2011 at 4:59 PM, Ohad Ben-Cohen <ohad@xxxxxxxxxx> wrote: > 2011/9/24 조경호 <pullip.cho@xxxxxxxxxxx>: >> This is the System MMU driver and IOMMU API implementation for >> Exynos4 SOC platforms. Exynos4 platforms has more than 10 System >> MMUs dedicated for each multimedia accellerators. >> >> Signed-off-by: KyongHo Cho <pullip.cho@xxxxxxxxxxx> > ... >> +static int exynos_iommu_fault_handler(struct iommu_domain *domain, >> + struct device *dev, unsigned long iova, int flags) >> +{ >> + struct exynos_iommu_domain *priv = domain->priv; >> + >> + dev_err(priv->dev, "%s occured at %p(Page table base: %p)\n", >> + sysmmu_fault_name[flags], (void *)iova, >> + (void *)(__pa(priv->pgtable))); >> + dev_err(priv->dev, "\t\tGenerating Kernel OOPS...\n"); >> + dev_err(priv->dev, "\t\tbecause it is unrecoverable.\n"); >> + dev_err(priv->dev, >> + "\t\tSet Fault handler with iommu_set_fault_handler().\n"); >> + dev_err(priv->dev, "\t\tto handle System MMU fault.\n"); >> + >> + BUG(); >> + >> + return 0; >> +} >> + >> +static int exynos_iommu_domain_init(struct iommu_domain *domain) >> +{ > ... >> + iommu_set_fault_handler(domain, &exynos_iommu_fault_handler); > > It doesn't make a lot of sense to set an iommu fault handler here; the > intention of iommu_set_fault_handler() is to allow upper layers to do > that. As you've noticed, it is default behavior for iommu fault. If an upper layer calls iommu_set_fault_handler(), it is replaced with the new one. > > Moreover, exynos_sysmmu_irq() anyway knows whenever a fault occurs, so > calling report_iommu_fault() just to have it call into the driver > again seems redundant. > I think calling report_iommu_fault() in exynos_sysmmu_irq() is rather simple. To do the default behavior in exynos_sysmmu_irq(), it must check if domain->handler is NULL or not. But the checking is also performed in report_iommu_fault() also. I think just calling report_iommu_fault() reduces redundancy. > If you want an exynos-specific behavior to occur whenever there's an > iommu fault, you should do that in exynos_sysmmu_irq itself. If you > just want a generic default logging behavior to occur whenever there's > no other fault handler installed, you might even want to consider > adding it to the IOMMU core. It is neither a specific behavior nor a generic logging. Just a default MMU fault report that can be replaceable with a fault handler that a device driver provides. Regards, Cho KyongHo. -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html