[PATCH] iommu/rockchip: Fix "is stall active" check

Heiko Stuebner
2016-04-05T17:21:27Z

Am Dienstag, 5. April 2016, 15:05:46 schrieb John Keeping:
> Since commit cd6438c5f844 ("iommu/rockchip: Reconstruct to support multi
> slaves") rk_iommu_is_stall_active() always returns false because the
> bitwise AND operates on the boolean flag promoted to an integer and a
> value that is either zero or BIT(2).
>
> Explicitly convert the right-hand value to a boolean so that both sides
> are guaranteed to be either zero or one.
>
> rk_iommu_is_paging_enabled() does not suffer from the same problem since
> RK_MMU_STATUS_PAGING_ENABLED is BIT(0), but let's apply the same change
> for consistency and to make it clear that it's correct without needing
> to lookup the value.
>
> Fixes: cd6438c5f844 ("iommu/rockchip: Reconstruct to support multi
> slaves") Signed-off-by: John Keeping <john@metanate.com>

Nice catch, thanks.

Reviewed-by: Heiko Stuebner <heiko@sntech.de>

John, out of curiosity, how did you find that problem? Excess stall error
messages or something else?

Thanks
Heiko

> ---
> drivers/iommu/rockchip-iommu.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/iommu/rockchip-iommu.c
> b/drivers/iommu/rockchip-iommu.c index a6f593a0a29e..5710a06c3049 100644
> --- a/drivers/iommu/rockchip-iommu.c
> +++ b/drivers/iommu/rockchip-iommu.c
> @@ -315,8 +315,8 @@ static bool rk_iommu_is_stall_active(struct rk_iommu
> *iommu) int i;
>
> for (i = 0; i < iommu->num_mmu; i++)
> - active &= rk_iommu_read(iommu->bases[i], RK_MMU_STATUS) &
> - RK_MMU_STATUS_STALL_ACTIVE;
> + active &= !!(rk_iommu_read(iommu->bases[i], RK_MMU_STATUS) &
> + RK_MMU_STATUS_STALL_ACTIVE);
>
> return active;
> }
> @@ -327,8 +327,8 @@ static bool rk_iommu_is_paging_enabled(struct rk_iommu
> *iommu) int i;
>
> for (i = 0; i < iommu->num_mmu; i++)
> - enable &= rk_iommu_read(iommu->bases[i], RK_MMU_STATUS) &
> - RK_MMU_STATUS_PAGING_ENABLED;
> + enable &= !!(rk_iommu_read(iommu->bases[i], RK_MMU_STATUS) &
> + RK_MMU_STATUS_PAGING_ENABLED);
>
> return enable;
> }