Hi, On 14.09.2020 10:29, Marek Szyprowski wrote: > On 11.09.2020 15:54, Michael Tretter wrote: >> Make the exynos_dsi driver a full drm bridge that can be found and used >> from other drivers. >> >> Other drivers can only attach to the bridge, if a mipi dsi device >> already attached to the bridge. This allows to defer the probe of the >> display pipe until the downstream bridges are available, too. >> >> Signed-off-by: Michael Tretter <m.tretter@xxxxxxxxxxxxxx> > This one (and the whole series applied) still fails on Exynos boards: > > [drm] Exynos DRM: using 11c00000.fimd device for DMA mapping operations > exynos-drm exynos-drm: bound 11c00000.fimd (ops fimd_component_ops) > OF: graph: no port node found in /soc/dsi@11c80000 > 8<--- cut here --- > Unable to handle kernel NULL pointer dereference at virtual address 00000084 > pgd = (ptrval) > [00000084] *pgd=00000000 > Internal error: Oops: 5 [#1] PREEMPT SMP ARM > Modules linked in: > CPU: 1 PID: 1 Comm: swapper/0 Not tainted > 5.9.0-rc4-next-20200911-00010-g417dc70d70ec #1608 > Hardware name: Samsung Exynos (Flattened Device Tree) > PC is at drm_bridge_attach+0x18/0x164 > LR is at exynos_dsi_bind+0x88/0xa8 > pc : [<c0628c08>] lr : [<c064d560>] psr: 20000013 > sp : ef0dfca8 ip : 00000002 fp : c13190e0 > r10: 00000000 r9 : ee46d580 r8 : c13190e0 > r7 : ee438800 r6 : 00000018 r5 : ef253810 r4 : ef39e840 > r3 : 00000000 r2 : 00000018 r1 : ef39e888 r0 : ef39e840 > Flags: nzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none > Control: 10c5387d Table: 4000404a DAC: 00000051 > Process swapper/0 (pid: 1, stack limit = 0x(ptrval)) > Stack: (0xef0dfca8 to 0xef0e0000) > ... > [<c0628c08>] (drm_bridge_attach) from [<c064d560>] > (exynos_dsi_bind+0x88/0xa8) > [<c064d560>] (exynos_dsi_bind) from [<c066a800>] > (component_bind_all+0xfc/0x290) > [<c066a800>] (component_bind_all) from [<c0649dc0>] > (exynos_drm_bind+0xe4/0x19c) > [<c0649dc0>] (exynos_drm_bind) from [<c066ad74>] > (try_to_bring_up_master+0x1e4/0x2c4) > [<c066ad74>] (try_to_bring_up_master) from [<c066b2b4>] > (component_master_add_with_match+0xd4/0x108) > [<c066b2b4>] (component_master_add_with_match) from [<c0649ae8>] > (exynos_drm_platform_probe+0xe4/0x110) > [<c0649ae8>] (exynos_drm_platform_probe) from [<c0674e6c>] > (platform_drv_probe+0x6c/0xa4) > [<c0674e6c>] (platform_drv_probe) from [<c067242c>] > (really_probe+0x200/0x4fc) > [<c067242c>] (really_probe) from [<c06728f0>] > (driver_probe_device+0x78/0x1fc) > [<c06728f0>] (driver_probe_device) from [<c0672cd8>] > (device_driver_attach+0x58/0x60) > [<c0672cd8>] (device_driver_attach) from [<c0672dbc>] > (__driver_attach+0xdc/0x174) > [<c0672dbc>] (__driver_attach) from [<c06701b4>] > (bus_for_each_dev+0x68/0xb4) > [<c06701b4>] (bus_for_each_dev) from [<c06714e8>] > (bus_add_driver+0x158/0x214) > [<c06714e8>] (bus_add_driver) from [<c0673c1c>] (driver_register+0x78/0x110) > [<c0673c1c>] (driver_register) from [<c0649ca8>] > (exynos_drm_init+0xe4/0x118) > [<c0649ca8>] (exynos_drm_init) from [<c0102484>] > (do_one_initcall+0x8c/0x42c) > [<c0102484>] (do_one_initcall) from [<c11011c0>] > (kernel_init_freeable+0x190/0x1dc) > [<c11011c0>] (kernel_init_freeable) from [<c0af7880>] > (kernel_init+0x8/0x118) > [<c0af7880>] (kernel_init) from [<c0100114>] (ret_from_fork+0x14/0x20) > Exception stack(0xef0dffb0 to 0xef0dfff8) > ... > ---[ end trace ee27f313f9ed9da1 ]--- > > # arm-linux-gnueabi-addr2line -e vmlinux c0628c08 > drivers/gpu/drm/drm_bridge.c:184 (discriminator 1) > > I will try to debug it a bit more today. The above crash has been caused by lack of in_bridge initialization to NULL in exynos_dsi_bind() in this patch. However, fixing it reveals another issue: [drm] Exynos DRM: using 11c00000.fimd device for DMA mapping operations exynos-drm exynos-drm: bound 11c00000.fimd (ops fimd_component_ops) OF: graph: no port node found in /soc/dsi@11c80000 8<--- cut here --- Unable to handle kernel NULL pointer dereference at virtual address 00000280 pgd = (ptrval) [00000280] *pgd=00000000 Internal error: Oops: 5 [#1] PREEMPT SMP ARM Modules linked in: CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.9.0-rc4-next-20200911-00010-g417dc70d70ec-dirty #1613 Hardware name: Samsung Exynos (Flattened Device Tree) PC is at __mutex_lock+0x54/0xb18 LR is at lock_is_held_type+0x80/0x138 pc : [<c0afc920>] lr : [<c0af63e8>] psr: 60000013 sp : ef0dfd30 ip : 33937b74 fp : c13193c8 r10: c1208eec r9 : 00000000 r8 : ee45f808 r7 : c19561a4 r6 : 00000000 r5 : 00000000 r4 : 0000024c r3 : 00000000 r2 : 00204140 r1 : c124f13c r0 : 00000000 Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none Control: 10c5387d Table: 4000404a DAC: 00000051 Process swapper/0 (pid: 1, stack limit = 0x(ptrval)) Stack: (0xef0dfd30 to 0xef0e0000) ... [<c0afc920>] (__mutex_lock) from [<c0afd400>] (mutex_lock_nested+0x1c/0x24) [<c0afd400>] (mutex_lock_nested) from [<c064d4b8>] (__exynos_dsi_host_attach+0x20/0x6c) [<c064d4b8>] (__exynos_dsi_host_attach) from [<c064d914>] (exynos_dsi_host_attach+0x70/0x194) [<c064d914>] (exynos_dsi_host_attach) from [<c0656b64>] (s6e8aa0_probe+0x1b0/0x218) [<c0656b64>] (s6e8aa0_probe) from [<c0672530>] (really_probe+0x200/0x4fc) [<c0672530>] (really_probe) from [<c06729f4>] (driver_probe_device+0x78/0x1fc) [<c06729f4>] (driver_probe_device) from [<c0672ddc>] (device_driver_attach+0x58/0x60) [<c0672ddc>] (device_driver_attach) from [<c0672ec0>] (__driver_attach+0xdc/0x174) [<c0672ec0>] (__driver_attach) from [<c06702b8>] (bus_for_each_dev+0x68/0xb4) [<c06702b8>] (bus_for_each_dev) from [<c06715ec>] (bus_add_driver+0x158/0x214) [<c06715ec>] (bus_add_driver) from [<c0673d20>] (driver_register+0x78/0x110) [<c0673d20>] (driver_register) from [<c0102484>] (do_one_initcall+0x8c/0x42c) [<c0102484>] (do_one_initcall) from [<c11011c0>] (kernel_init_freeable+0x190/0x1dc) [<c11011c0>] (kernel_init_freeable) from [<c0af7988>] (kernel_init+0x8/0x118) [<c0af7988>] (kernel_init) from [<c0100114>] (ret_from_fork+0x14/0x20) Exception stack(0xef0dffb0 to 0xef0dfff8) ... ---[ end trace c06e996ec2e8234d ]--- This means that dsi->encoder.dev is not initialized in __exynos_dsi_host_attach(). This happens, because drm_bridge_attach() in exynos_dsi_bind() returned earlier -517 (deferred probe), what causes cleanup of encoder and release of all drm resources. Then however, the panel tries to register itself and exynos_dsi_host_attach() tries to access the released encoder (which is zeroed in drm_encoder_release) and rest of resources, what causes failure. It looks that something is missing. Maybe mipi host has to be registered later, when bridge is ready? I have no idea how it is handled before this patch. Andrzej, could you comment it a bit? Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland
