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[v2,1/5] iommu: sun50i: clear bypass register

Message ID 20240616224056.29159-2-andre.przywara@arm.com (mailing list archive)
State New
Headers show
Series iommu: sun50i: Add Allwinner H616 support | expand

Commit Message

Andre Przywara June 16, 2024, 10:40 p.m. UTC 
From: Jernej Skrabec <jernej.skrabec@gmail.com>

The Allwinner H6 IOMMU has a bypass register, which allows to circumvent
the page tables for each possible master. The reset value for this
register is 0, which disables the bypass.
The Allwinner H616 IOMMU resets this register to 0x7f, which activates
the bypass for all masters, which is not what we want.

Always clear this register to 0, to enforce the usage of page tables,
and make this driver compatible with the H616 in this respect.

Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 drivers/iommu/sun50i-iommu.c | 1 +
 1 file changed, 1 insertion(+)

Comments

Chen-Yu Tsai June 20, 2024, 10:16 a.m. UTC | #1 
On Mon, Jun 17, 2024 at 6:42 AM Andre Przywara <andre.przywara@arm.com> wrote:
>
> From: Jernej Skrabec <jernej.skrabec@gmail.com>
>
> The Allwinner H6 IOMMU has a bypass register, which allows to circumvent
> the page tables for each possible master. The reset value for this
> register is 0, which disables the bypass.
> The Allwinner H616 IOMMU resets this register to 0x7f, which activates
> the bypass for all masters, which is not what we want.
>
> Always clear this register to 0, to enforce the usage of page tables,
> and make this driver compatible with the H616 in this respect.
>
> Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>
> Signed-off-by: Andre Przywara <andre.przywara@arm.com>

Reviewed-by: Chen-Yu Tsai <wens@csie.org>

> ---
>  drivers/iommu/sun50i-iommu.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/iommu/sun50i-iommu.c b/drivers/iommu/sun50i-iommu.c
> index c519b991749d7..dd3f07384624c 100644
> --- a/drivers/iommu/sun50i-iommu.c
> +++ b/drivers/iommu/sun50i-iommu.c
> @@ -452,6 +452,7 @@ static int sun50i_iommu_enable(struct sun50i_iommu *iommu)
>                     IOMMU_TLB_PREFETCH_MASTER_ENABLE(3) |
>                     IOMMU_TLB_PREFETCH_MASTER_ENABLE(4) |
>                     IOMMU_TLB_PREFETCH_MASTER_ENABLE(5));
> +       iommu_write(iommu, IOMMU_BYPASS_REG, 0);
>         iommu_write(iommu, IOMMU_INT_ENABLE_REG, IOMMU_INT_MASK);
>         iommu_write(iommu, IOMMU_DM_AUT_CTRL_REG(SUN50I_IOMMU_ACI_NONE),
>                     IOMMU_DM_AUT_CTRL_RD_UNAVAIL(SUN50I_IOMMU_ACI_NONE, 0) |
> --
> 2.39.4
>
diff mbox series

Patch

diff --git a/drivers/iommu/sun50i-iommu.c b/drivers/iommu/sun50i-iommu.c
index c519b991749d7..dd3f07384624c 100644
--- a/drivers/iommu/sun50i-iommu.c
+++ b/drivers/iommu/sun50i-iommu.c
@@ -452,6 +452,7 @@  static int sun50i_iommu_enable(struct sun50i_iommu *iommu)
 		    IOMMU_TLB_PREFETCH_MASTER_ENABLE(3) |
 		    IOMMU_TLB_PREFETCH_MASTER_ENABLE(4) |
 		    IOMMU_TLB_PREFETCH_MASTER_ENABLE(5));
+	iommu_write(iommu, IOMMU_BYPASS_REG, 0);
 	iommu_write(iommu, IOMMU_INT_ENABLE_REG, IOMMU_INT_MASK);
 	iommu_write(iommu, IOMMU_DM_AUT_CTRL_REG(SUN50I_IOMMU_ACI_NONE),
 		    IOMMU_DM_AUT_CTRL_RD_UNAVAIL(SUN50I_IOMMU_ACI_NONE, 0) |