Messages in this thread | | | Date | Tue, 17 May 2022 11:26:47 +0200 | Subject | Re: [PATCH 2/2] iommu: mtk_iommu: Add support for MT6795 Helio X10 M4Us | From | AngeloGioacchino Del Regno <> |
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Il 17/05/22 11:08, Yong Wu ha scritto: > On Fri, 2022-05-13 at 17:14 +0200, AngeloGioacchino Del Regno wrote: >> Add support for the M4Us found in the MT6795 Helio X10 SoC. >> >> Signed-off-by: AngeloGioacchino Del Regno < >> angelogioacchino.delregno@collabora.com> >> --- >> drivers/iommu/mtk_iommu.c | 20 +++++++++++++++++++- >> 1 file changed, 19 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c >> index 71b2ace74cd6..3d802dd3f377 100644 >> --- a/drivers/iommu/mtk_iommu.c >> +++ b/drivers/iommu/mtk_iommu.c >> @@ -157,6 +157,7 @@ >> enum mtk_iommu_plat { >> M4U_MT2712, >> M4U_MT6779, >> + M4U_MT6795, >> M4U_MT8167, >> M4U_MT8173, >> M4U_MT8183, >> @@ -953,7 +954,8 @@ static int mtk_iommu_hw_init(const struct >> mtk_iommu_data *data, unsigned int ban >> * Global control settings are in bank0. May re-init these >> global registers >> * since no sure if there is bank0 consumers. >> */ >> - if (data->plat_data->m4u_plat == M4U_MT8173) { >> + if (data->plat_data->m4u_plat == M4U_MT6795 || >> + data->plat_data->m4u_plat == M4U_MT8173) { >> regval = F_MMU_PREFETCH_RT_REPLACE_MOD | >> F_MMU_TF_PROT_TO_PROGRAM_ADDR_MT8173; >> } else { >> @@ -1138,6 +1140,9 @@ static int mtk_iommu_probe(struct >> platform_device *pdev) >> case M4U_MT2712: >> p = "mediatek,mt2712-infracfg"; >> break; >> + case M4U_MT6795: >> + p = "mediatek,mt6795-infracfg"; >> + break; >> case M4U_MT8173: >> p = "mediatek,mt8173-infracfg"; >> break; >> @@ -1404,6 +1409,18 @@ static const struct mtk_iommu_plat_data >> mt6779_data = { >> .larbid_remap = {{0}, {1}, {2}, {3}, {5}, {7, 8}, {10}, {9}}, >> }; >> >> +static const struct mtk_iommu_plat_data mt6795_data = { >> + .m4u_plat = M4U_MT6795, >> + .flags = HAS_4GB_MODE | HAS_BCLK | RESET_AXI | >> + HAS_LEGACY_IVRP_PADDR | MTK_IOMMU_TYPE_MM, >> + .inv_sel_reg = REG_MMU_INV_SEL_GEN1, >> + .banks_num = 1, >> + .banks_enable = {true}, >> + .iova_region = single_domain, >> + .iova_region_nr = ARRAY_SIZE(single_domain), >> + .larbid_remap = {{0}, {1}, {2}, {3}, {4}}, /* Linear mapping. >> */ >> +}; > > This is nearly same with mt8173_data. mt8173 has one more larb than > mt6795, its larbid_remap is also ok for mt6795. >
I think that we should be explicit about the larbid_remap property, since mt6795 has one less larb, we should explicitly say that like I did there... that's only for human readability I admit ... but, still, I wouldn't want to see people thinking that MT6795 has 6 LARBs because they've read that larbid_remap having 6 entries.
> thus it looks we could use mt8173 as the backward compatible. > compatible = "mediatek,mt6795-m4u", > "mediatek,mt8173-m4u"; > > After this, the only thing is about "mediatek,mt6795-infracfg". we have > to try again with mediatek,mt6795-infracfg after mediatek,mt8173- > infracfg fail. I think we should allow the backward case in 4GB mode > judgment if we have. > > What's your opinion? or some other suggestion? > Thanks.
I know, I may have a plan for that, but I wanted to have a good reason to propose such a thing, as if it's just about two SoCs needing that, there would be no good reason to get things done differently.
...so, in order to provide a good cleanup, we have two possible roads to follow here: either we add a generic "mediatek,infracfg" compatible to the infra node (but I don't like that), or we can do it like it was previously done in mtk-pm-domains.c (I prefer that approach):
iommu: iommu@somewhere { ... something ... mediatek,infracfg = <&infracfg>; };
infracfg = syscon_regmap_lookup_by_compatible(node, "mediatek,infracfg"); if (IS_ERR(infracfg)) { /* try with the older way */ switch (...) { case .... p = "mediatek,mt2712-infracfg"; ... blah blah ... } /* legacy also failed, ouch! */ if (IS_ERR(infracfg)) return PTR_ERR(infracfg); }
ret = regmap_read ... etc etc etc
Cheers, Angelo
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