[PATCH v7 08/14] iommu/mediatek: Add a gap for the iova regions

Yong Wu
2023-04-11T09:34:13Z

As the removed property in the vcodec dt-binding, the property is:
dma-ranges = <0x1 0x0 0x0 0x40000000 0x0 0xfff00000>;

The length is 0xfff0_0000 rather than 0x1_0000_0000, this means it
requires 1M as a gap. This is because the end address for some vcodec
HW is (address + size). If the size is 4G, the end address may be
0x2_0000_0000, and the width for vcodec register only is 32, then the
HW may get the ZERO address.

Currently the consumer's dma-ranges property doesn't work, IOMMU
has to consider this case. Add a bigger gap(8M) for all the regions
to avoid it.

Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
---
drivers/iommu/mtk_iommu.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index 2c2a64c1712a..0e104bb27010 100644
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c
@@ -332,8 +332,10 @@ static LIST_HEAD(m4ulist); /* List all the M4U HWs */

#define for_each_m4u(data, head) list_for_each_entry(data, head, list)

+#define MTK_IOMMU_IOVA_SZ_4G (SZ_4G - SZ_8M) /* 8M as gap */
+
static const struct mtk_iommu_iova_region single_domain[] = {
- {.iova_base = 0, .size = SZ_4G},
+ {.iova_base = 0, .size = MTK_IOMMU_IOVA_SZ_4G},
};

#define MT8192_MULTI_REGION_NR_MAX 6
@@ -342,11 +344,11 @@ static const struct mtk_iommu_iova_region single_domain[] = {
MT8192_MULTI_REGION_NR_MAX : 1)

static const struct mtk_iommu_iova_region mt8192_multi_dom[MT8192_MULTI_REGION_NR] = {
- { .iova_base = 0x0, .size = SZ_4G}, /* 0 ~ 4G */
+ { .iova_base = 0x0, .size = MTK_IOMMU_IOVA_SZ_4G}, /* 0 ~ 4G, */
#if IS_ENABLED(CONFIG_ARCH_DMA_ADDR_T_64BIT)
- { .iova_base = SZ_4G, .size = SZ_4G}, /* 4G ~ 8G */
- { .iova_base = SZ_4G * 2, .size = SZ_4G}, /* 8G ~ 12G */
- { .iova_base = SZ_4G * 3, .size = SZ_4G}, /* 12G ~ 16G */
+ { .iova_base = SZ_4G, .size = MTK_IOMMU_IOVA_SZ_4G}, /* 4G ~ 8G */
+ { .iova_base = SZ_4G * 2, .size = MTK_IOMMU_IOVA_SZ_4G}, /* 8G ~ 12G */
+ { .iova_base = SZ_4G * 3, .size = MTK_IOMMU_IOVA_SZ_4G}, /* 12G ~ 16G */

{ .iova_base = 0x240000000ULL, .size = 0x4000000}, /* CCU0 */
{ .iova_base = 0x244000000ULL, .size = 0x4000000}, /* CCU1 */
--
2.25.1