On Thu, Aug 22, 2019 at 04:56:26PM +0800, Yong Wu wrote:

On Wed, 2019-08-21 at 16:24 +0100, Will Deacon wrote:

quoted

On Wed, Aug 21, 2019 at 09:53:12PM +0800, Yong Wu wrote:

quoted

MediaTek extend the arm v7s descriptor to support up to 34 bits PA where
the bit32 and bit33 are encoded in the bit9 and bit4 of the PTE
respectively. Meanwhile the iova still is 32bits.

Regarding whether the pagetable address could be over 4GB, the mt8183
support it while the previous mt8173 don't, thus keep it as is.

Signed-off-by: Yong Wu <yong.wu@mediatek.com>
---
 drivers/iommu/io-pgtable-arm-v7s.c | 32 +++++++++++++++++++++++++-------
 include/linux/io-pgtable.h         |  7 +++----
 2 files changed, 28 insertions(+), 11 deletions(-)

[...]

quoted

@@ -731,7 +747,9 @@ static struct io_pgtable *arm_v7s_alloc_pgtable(struct io_pgtable_cfg *cfg,
 {
 	struct arm_v7s_io_pgtable *data;
 
-	if (cfg->ias > ARM_V7S_ADDR_BITS || cfg->oas > ARM_V7S_ADDR_BITS)
+	if (cfg->ias > ARM_V7S_ADDR_BITS ||
+	    (cfg->oas > ARM_V7S_ADDR_BITS &&
+	     !(cfg->quirks & IO_PGTABLE_QUIRK_ARM_MTK_EXT)))

Please can you instead change arm_v7s_alloc_pgtable() so that it allows an
ias of up to 34 when the IO_PGTABLE_QUIRK_ARM_MTK_EXT is set?

Here I only simply skip the oas checking for our case. then which way do
your prefer?  something like you commented before:?


	if (cfg->ias > ARM_V7S_ADDR_BITS)
		return NULL;

	if (cfg->quirks & IO_PGTABLE_QUIRK_ARM_MTK_EXT) {
		if (!IS_ENABLED(CONFIG_PHYS_ADDR_T_64BIT))
			cfg->oas = min(cfg->oas, ARM_V7S_ADDR_BITS);

Isn't this always 32 for your IOMMUs?

		else if (cfg->oas > 34)
			return NULL;
	} else if (cfg->oas > ARM_V7S_ADDR_BITS) {
		return NULL;
	}

How about:

	unsigned int oas_max = ARM_V7S_ADDR_BITS;

	if (cfg->ias > ARM_V7S_ADDR_BITS)
		return NULL;

	if (IS_ENABLED(CONFIG_PHYS_ADDR_T_64BIT) &&
	    cfg->quirks & IO_PGTABLE_QUIRK_ARM_MTK_EXT)
		oas_max = 34;

	if (cfg->oas > oas_max)
		return NULL;

Will