> -----Original Message-----
> From: iommu-boun...@lists.linux-foundation.org [mailto:iommu-
> boun...@lists.linux-foundation.org] On Behalf Of Olav Haugan
> Sent: Monday, June 30, 2014 10:22 PM
> To: linux-arm-ker...@lists.infradead.org; iommu@lists.linux-
> foundation.org
> Cc: linux-arm-...@vger.kernel.org; will.dea...@arm.com;
> thierry.red...@gmail.com; vgan...@codeaurora.org
> Subject: [RFC/PATCH 7/7] iommu-api: Add domain attribute to enable
> coherent HTW
>
> Add a new iommu domain attribute that can be used to enable cache
> coherent hardware table walks (HTW) by the SMMU. HTW might be supported
> by the SMMU HW but depending on the use case and the usage of the SMMU in
> the SoC it might not be always beneficial to always turn on coherent HTW
> for all domains/iommu's.
>
[Sethi Varun-B16395] Why won't you want to use the coherent table walk feature?
> Signed-off-by: Olav Haugan <ohau...@codeaurora.org>
> ---
> drivers/iommu/msm_iommu-v1.c | 16 ++++++++++++++++
> include/linux/iommu.h | 1 +
> 2 files changed, 17 insertions(+)
>
> diff --git a/drivers/iommu/msm_iommu-v1.c b/drivers/iommu/msm_iommu-v1.c
> index 2c574ef..e163ffc 100644
> --- a/drivers/iommu/msm_iommu-v1.c
> +++ b/drivers/iommu/msm_iommu-v1.c
> @@ -1456,8 +1456,16 @@ static int msm_domain_get_attr(struct iommu_domain
> *domain,
> enum iommu_attr attr, void *data) {
> s32 ret = 0;
> + struct msm_iommu_priv *priv = domain->priv;
>
> switch (attr) {
> + case DOMAIN_ATTR_COHERENT_HTW:
> + {
> + s32 *int_ptr = (s32 *) data;
> +
> + *int_ptr = priv->pt.redirect;
> + break;
> + }
> default:
> pr_err("Unsupported attribute type\n");
> ret = -EINVAL;
> @@ -1471,8 +1479,16 @@ static int msm_domain_set_attr(struct iommu_domain
> *domain,
> enum iommu_attr attr, void *data) {
> s32 ret = 0;
> + struct msm_iommu_priv *priv = domain->priv;
>
> switch (attr) {
> + case DOMAIN_ATTR_COHERENT_HTW:
> + {
> + s32 *int_ptr = (s32 *) data;
> +
> + priv->pt.redirect = *int_ptr;
> + break;
> + }
> default:
> pr_err("Unsupported attribute type\n");
> ret = -EINVAL;
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h index
> 63dca6d..6d9596d 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -81,6 +81,7 @@ enum iommu_attr {
> DOMAIN_ATTR_FSL_PAMU_STASH,
> DOMAIN_ATTR_FSL_PAMU_ENABLE,
> DOMAIN_ATTR_FSL_PAMUV1,
> + DOMAIN_ATTR_COHERENT_HTW,
[Sethi Varun-B16395] Would it make sense to represent this as
DOMAIN_ATTR_SMMU_COHERENT_HTW? I believe this is specific to SMMU.
-Varun
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