On Mon, Mar 09, 2015 at 12:11:43PM +0000, Yong Wu wrote: > On Fri, 2015-03-06 at 10:58 +0000, Will Deacon wrote: > > On Fri, Mar 06, 2015 at 10:48:17AM +0000, yong.wu@xxxxxxxxxxxx wrote: > > > From: Yong Wu <yong.wu@xxxxxxxxxxxx> > > > > > > This patch adds support for mediatek m4u (MultiMedia Memory Management Unit). > > > Currently this only supports m4u gen 2 with 2 levels of page table on mt8173. > > > > [...] > > > > > +/* 2 level pagetable: pgd -> pte */ > > > +#define F_PTE_TYPE_GET(regval) (regval & 0x3) > > > +#define F_PTE_TYPE_LARGE BIT(0) > > > +#define F_PTE_TYPE_SMALL BIT(1) > > > +#define F_PTE_B_BIT BIT(2) > > > +#define F_PTE_C_BIT BIT(3) > > > +#define F_PTE_BIT32_BIT BIT(9) > > > +#define F_PTE_S_BIT BIT(10) > > > +#define F_PTE_NG_BIT BIT(11) > > > +#define F_PTE_PA_LARGE_MSK (~0UL << 16) > > > +#define F_PTE_PA_LARGE_GET(regval) ((regval >> 16) & 0xffff) > > > +#define F_PTE_PA_SMALL_MSK (~0UL << 12) > > > +#define F_PTE_PA_SMALL_GET(regval) ((regval >> 12) & (~0)) > > > +#define F_PTE_TYPE_IS_LARGE_PAGE(pte) ((imu_pte_val(pte) & 0x3) == \ > > > + F_PTE_TYPE_LARGE) > > > +#define F_PTE_TYPE_IS_SMALL_PAGE(pte) ((imu_pte_val(pte) & 0x3) == \ > > > + F_PTE_TYPE_SMALL) > > > > This looks like the ARM short-descriptor format to me. Could you please > > add a new page table format to the io-pgtable code, so that other IOMMU > > drivers can make use of this? I know there was some interest in using > > short descriptor for the ARM SMMU, for example. > Currently I not familiar with the io-pgtable,I may need some time > for it and the ARM short-descriptor. Well, you can read the LPAE version I wrote in io-pgtable-arm.c for some inspiration (it's used by arm-smmu.c and ipmmu-vmsa.c). > And there are some difference between mediatek's pagetable with the > standard short-descriptor, like bit 9. we use it for the dram over 4GB. > Then how should we do if there are some difference. That can easily be handled using a quirk (see, for example, IO_PGTABLE_QUIRK_ARM_NS). Will -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
