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Message-ID: <8b31b1d2-4ed7-11a1-2124-4641c8f3abcd@gmail.com>
Date: Wed, 15 Jun 2022 14:09:49 +0200
From: Matthias Brugger <matthias.bgg@...il.com>
To: AngeloGioacchino Del Regno
<angelogioacchino.delregno@...labora.com>, yong.wu@...iatek.com
Cc: joro@...tes.org, will@...nel.org, robh+dt@...nel.org,
krzysztof.kozlowski+dt@...aro.org,
iommu@...ts.linux-foundation.org,
linux-mediatek@...ts.infradead.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
krzysztof.kozlowski@...aro.org
Subject: Re: [PATCH v3 6/6] iommu: mtk_iommu: Lookup phandle to retrieve
syscon to pericfg
On 09/06/2022 12:08, AngeloGioacchino Del Regno wrote:
> On some SoCs (of which only MT8195 is supported at the time of writing),
> the "R" and "W" (I/O) enable bits for the IOMMUs are in the pericfg_ao
> register space and not in the IOMMU space: as it happened already with
> infracfg, it is expected that this list will grow.
>
> Instead of specifying pericfg compatibles on a per-SoC basis, following
> what was done with infracfg, let's lookup the syscon by phandle instead.
>
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
> ---
> drivers/iommu/mtk_iommu.c | 23 +++++++++++++----------
> 1 file changed, 13 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> index 90685946fcbe..0ea0848581e9 100644
> --- a/drivers/iommu/mtk_iommu.c
> +++ b/drivers/iommu/mtk_iommu.c
> @@ -138,6 +138,8 @@
> /* PM and clock always on. e.g. infra iommu */
> #define PM_CLK_AO BIT(15)
> #define IFA_IOMMU_PCIE_SUPPORT BIT(16)
> +/* IOMMU I/O (r/w) is enabled using PERICFG_IOMMU_1 register */
> +#define HAS_PERI_IOMMU1_REG BIT(17)
From what I can see MTK_IOMMU_TYPE_INFRA is only set in MT8195 which uses
pericfg. So we don't need a new flag here. For me the flag name
MTK_IOMMU_TYPE_INFRA was confusing as it has nothing to do with the use of
infracfg. I'll hijack this patch to provide some feedback on the actual code,
please see below.
>
> #define MTK_IOMMU_HAS_FLAG_MASK(pdata, _x, mask) \
> ((((pdata)->flags) & (mask)) == (_x))
> @@ -187,7 +189,6 @@ struct mtk_iommu_plat_data {
> u32 flags;
> u32 inv_sel_reg;
>
> - char *pericfg_comp_str;
> struct list_head *hw_list;
> unsigned int iova_region_nr;
> const struct mtk_iommu_iova_region *iova_region;
> @@ -1218,14 +1219,16 @@ static int mtk_iommu_probe(struct platform_device *pdev)
> goto out_runtime_disable;
> }
> } else if (MTK_IOMMU_IS_TYPE(data->plat_data, MTK_IOMMU_TYPE_INFRA) &&
> - data->plat_data->pericfg_comp_str) {
Check for pericfg_comp_str is not needed, we only have one platform that uses
MTK_IOMMU_TYPE_INFRA.
> - infracfg = syscon_regmap_lookup_by_compatible(data->plat_data->pericfg_comp_str);
We can do something like this to make the code clearer:
data->pericfg =
syscon_regmap_lookup_by_compatible(data->plat_data->pericfg_comp_str);
if (IS_ERR(data->pericfg)) {
Using infracfg variable here is confusing as it has nothing to do with infracfg
used with HAS_4GB_MODE flag.
Regards,
Matthias
> - if (IS_ERR(infracfg)) {
> - ret = PTR_ERR(infracfg);
> - goto out_runtime_disable;
> + MTK_IOMMU_HAS_FLAG(data->plat_data, HAS_PERI_IOMMU1_REG)) {
> + data->pericfg = syscon_regmap_lookup_by_phandle(dev->of_node, "mediatek,pericfg");
> + if (IS_ERR(data->pericfg)) {
> + p = "mediatek,mt8195-pericfg_ao";
> + data->pericfg = syscon_regmap_lookup_by_compatible(p);
> + if (IS_ERR(data->pericfg)) {
> + ret = PTR_ERR(data->pericfg);
> + goto out_runtime_disable;
> + }
> }
> -
> - data->pericfg = infracfg;
> }
>
> platform_set_drvdata(pdev, data);
> @@ -1484,8 +1487,8 @@ static const struct mtk_iommu_plat_data mt8192_data = {
> static const struct mtk_iommu_plat_data mt8195_data_infra = {
> .m4u_plat = M4U_MT8195,
> .flags = WR_THROT_EN | DCM_DISABLE | STD_AXI_MODE | PM_CLK_AO |
> - MTK_IOMMU_TYPE_INFRA | IFA_IOMMU_PCIE_SUPPORT,
> - .pericfg_comp_str = "mediatek,mt8195-pericfg_ao",
> + HAS_PERI_IOMMU1_REG | MTK_IOMMU_TYPE_INFRA |
> + IFA_IOMMU_PCIE_SUPPORT,
> .inv_sel_reg = REG_MMU_INV_SEL_GEN2,
> .banks_num = 5,
> .banks_enable = {true, false, false, false, true},
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