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From:   Evan Green <evgreen@chromium.org>
Date:   Mon, 13 Apr 2020 16:12:44 -0700
Message-ID: <CAE=gft7HFBc7XtgiV1hkG-m3ONMUiE2vu8Vg_7Mu1dfe2BjYpA@mail.gmail.com>
Subject: Re: [PATCH 2/2] iommu/arm-smmu: Allow client devices to select direct mapping
To:     Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Cc:     Will Deacon <will@kernel.org>, Robin Murphy <robin.murphy@arm.com>,
        Joerg Roedel <joro@8bytes.org>,
        Jordan Crouse <jcrouse@codeaurora.org>,
        Rob Clark <robdclark@gmail.com>,
        iommu@lists.linux-foundation.org,
        linux-arm Mailing List <linux-arm-kernel@lists.infradead.org>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-arm-msm <linux-arm-msm@vger.kernel.org>,
        Stephen Boyd <swboyd@chromium.org>,
        Matthias Kaehlcke <mka@chromium.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Rajendra Nayak <rnayak@codeaurora.org>,
        Tomasz Figa <tfiga@chromium.org>
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On Wed, Jan 22, 2020 at 3:48 AM Sai Prakash Ranjan
<saiprakash.ranjan@codeaurora.org> wrote:
>
> From: Jordan Crouse <jcrouse@codeaurora.org>
>
> Some client devices want to directly map the IOMMU themselves instead
> of using the DMA domain. Allow those devices to opt in to direct
> mapping by way of a list of compatible strings.
>
> Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
> Co-developed-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
> Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
> ---
>  drivers/iommu/arm-smmu-qcom.c | 39 +++++++++++++++++++++++++++++++++++
>  drivers/iommu/arm-smmu.c      |  3 +++
>  drivers/iommu/arm-smmu.h      |  5 +++++
>  3 files changed, 47 insertions(+)
>
> diff --git a/drivers/iommu/arm-smmu-qcom.c b/drivers/iommu/arm-smmu-qcom.c
> index 64a4ab270ab7..ff746acd1c81 100644
> --- a/drivers/iommu/arm-smmu-qcom.c
> +++ b/drivers/iommu/arm-smmu-qcom.c
> @@ -3,6 +3,7 @@
>   * Copyright (c) 2019, The Linux Foundation. All rights reserved.
>   */
>
> +#include <linux/of_device.h>
>  #include <linux/qcom_scm.h>
>
>  #include "arm-smmu.h"
> @@ -11,6 +12,43 @@ struct qcom_smmu {
>         struct arm_smmu_device smmu;
>  };
>
> +static const struct arm_smmu_client_match_data qcom_adreno = {
> +       .direct_mapping = true,
> +};
> +
> +static const struct arm_smmu_client_match_data qcom_mdss = {
> +       .direct_mapping = true,

I don't actually see direct_mapping being used. Shouldn't this member
be checked somewhere?

-Evan