03.03.2021 12:47, Dmitry Osipenko пишет: > 03.03.2021 02:08, Nicolin Chen пишет: >> On Sat, Feb 27, 2021 at 12:59:17PM +0300, Dmitry Osipenko wrote: >>> 25.02.2021 09:27, Nicolin Chen пишет: >>> ... >>>>> The partially revert should be okay, but it's not clear to me what makes >>>>> difference for T124 since I don't see that problem on T30, which also >>>>> has active display at a boot time. >>>> Hmm..do you see ->attach_dev() is called from host1x_client_iommu_attach >>>> or from of_dma_configure_id/arch_setup_dma_ops? >>>> >>> I applied yours debug-patch, please see dmesg.txt attached to the email. >>> Seems probe-defer of the tegra-dc driver prevents the implicit >>> tegra_smmu_attach_dev, so it happens to work by accident. >>> [ 0.327826] tegra-dc 54200000.dc: -------tegra_smmu_of_xlate: id 1 >>> [ 0.328641] [<c052ec75>] (tegra_smmu_of_xlate) from [<c052e591>] (of_iommu_xlate+0x51/0x70) >>> [ 0.328740] [<c052e591>] (of_iommu_xlate) from [<c052e6d7>] (of_iommu_configure+0x127/0x150) >>> [ 0.328896] [<c052e6d7>] (of_iommu_configure) from [<c073f697>] (of_dma_configure_id+0x1fb/0x2ec) >>> [ 0.329060] [<c073f697>] (of_dma_configure_id) from [<c059743f>] (really_probe+0x7b/0x2a0) >>> [ 0.331438] tegra-dc 54200000.dc: --------tegra_smmu_probe_device, 822 >>> [ 0.332234] [<c052ebed>] (tegra_smmu_probe_device) from [<c052bd6d>] (__iommu_probe_device+0x35/0x1c4) >>> [ 0.332391] [<c052bd6d>] (__iommu_probe_device) from [<c052c3cd>] (iommu_probe_device+0x19/0xec) >>> [ 0.332545] [<c052c3cd>] (iommu_probe_device) from [<c052e6ab>] (of_iommu_configure+0xfb/0x150) >>> [ 0.332701] [<c052e6ab>] (of_iommu_configure) from [<c073f697>] (of_dma_configure_id+0x1fb/0x2ec) >>> [ 0.332804] [<c073f697>] (of_dma_configure_id) from [<c059743f>] (really_probe+0x7b/0x2a0) >>> [ 0.335202] tegra-dc 54200000.dc: ---------iommu_group_get_for_dev, 1572 >>> [ 0.335292] tegra-dc 54200000.dc: ---------tegra_smmu_device_group, 862 >>> [ 0.335474] tegra-dc 54200000.dc: ---------tegra_smmu_device_group, 909: 1: drm >>> [ 0.335566] tegra-dc 54200000.dc: ---------iommu_group_get_for_dev, 1574 >>> [ 0.335718] tegra-dc 54200000.dc: ---------iommu_group_add_device, 858 >>> [ 0.335862] tegra-dc 54200000.dc: Adding to iommu group 1 >>> [ 0.335955] tegra-dc 54200000.dc: ---------iommu_alloc_default_domain, 1543: type 3 >>> [ 0.336101] iommu: ------iommu_group_alloc_default_domain: platform, (null), drm >>> [ 0.336187] ---------tegra_smmu_domain_alloc, 284: type 3 >> [ 0.336968] [<c0a0ff45>] (tegra_smmu_domain_alloc) from [<c0a0f87b>] (iommu_group_alloc_default_domain+0x4b/0xfa) >>> [ 0.337127] [<c0a0f87b>] (iommu_group_alloc_default_domain) from [<c052c41d>] (iommu_probe_device+0x69/0xec) >>> [ 0.337285] [<c052c41d>] (iommu_probe_device) from [<c052e6ab>] (of_iommu_configure+0xfb/0x150) >>> [ 0.337441] [<c052e6ab>] (of_iommu_configure) from [<c073f697>] (of_dma_configure_id+0x1fb/0x2ec) >>> [ 0.337599] [<c073f697>] (of_dma_configure_id) from [<c059743f>] (really_probe+0x7b/0x2a0) >>> [ 0.339913] tegra-dc 54200000.dc: ---------iommu_probe_device, 272 >>> [ 0.348144] tegra-dc 54200000.dc: failed to probe RGB output: -517 >> Hmm..not sure where this EPROBE_DEFER comes from. > DC driver on Nexus 7 depends on LVDS bridge and display panel, which > cause the probe defer. > >> But you are right, >> as of_dma_configure_id() returns because of that so it didn't run to >> arch_setup_dma_ops() call, which allocates an UNMANAGED iommu domain >> and attaches DC to it on Tegra124. >> >> By the way, anyone can accept this change? It doesn't feel right to >> leave a regression in the newer release... Guys, I have a good and bad news. The good news is that I figured out why I didn't see this problem on Nexus 7 and the reason is that I had CONFIG_ARM_DMA_USE_IOMMU=n. The other good news is that I have a simple workaround which fixes the implicit IOMMU problem by deferring the ASID enabling for display clients. The bad news is that CONFIG_ARM_DMA_USE_IOMMU=y breaks GPU (DRM, host1x) drivers because they aren't properly prepared to this case and CONFIG_ARM_DMA_USE_IOMMU is enabled in multi-platform kernel config. I will try to fix up the drivers, but not sure how much time this may take.
