Hi Saravana, On 19.05.2020 08:48, Saravana Kannan wrote: > On Mon, May 18, 2020 at 11:25 PM Marek Szyprowski > <m.szyprowski@xxxxxxxxxxx> wrote: >> On 15.05.2020 07:35, Saravana Kannan wrote: >>> The fw_devlink_pause() and fw_devlink_resume() APIs allow batching the >>> parsing of the device tree nodes when a lot of devices are added. This >>> will significantly cut down parsing time (as much a 1 second on some >>> systems). So, use them when adding devices for all the top level device >>> tree nodes in a system. >>> >>> Signed-off-by: Saravana Kannan <saravanak@xxxxxxxxxx> >> This patch recently landed in linux-next 20200518. Sadly, it causes >> regression on Samsung Exynos5433-based TM2e board: >> >> s3c64xx-spi 14d30000.spi: Failed to get RX DMA channel >> s3c64xx-spi 14d50000.spi: Failed to get RX DMA channel >> s3c64xx-spi 14d30000.spi: Failed to get RX DMA channel >> s3c64xx-spi 14d50000.spi: Failed to get RX DMA channel >> s3c64xx-spi 14d30000.spi: Failed to get RX DMA channel >> >> Internal error: synchronous external abort: 96000210 [#1] PREEMPT SMP >> Modules linked in: >> CPU: 0 PID: 50 Comm: kworker/0:1 Not tainted 5.7.0-rc5+ #701 >> Hardware name: Samsung TM2E board (DT) >> Workqueue: events deferred_probe_work_func >> pstate: 60000005 (nZCv daif -PAN -UAO) >> pc : samsung_i2s_probe+0x768/0x8f0 >> lr : samsung_i2s_probe+0x688/0x8f0 >> ... >> Call trace: >> samsung_i2s_probe+0x768/0x8f0 >> platform_drv_probe+0x50/0xa8 >> really_probe+0x108/0x370 >> driver_probe_device+0x54/0xb8 >> __device_attach_driver+0x90/0xc0 >> bus_for_each_drv+0x70/0xc8 >> __device_attach+0xdc/0x140 >> device_initial_probe+0x10/0x18 >> bus_probe_device+0x94/0xa0 >> deferred_probe_work_func+0x70/0xa8 >> process_one_work+0x2a8/0x718 >> worker_thread+0x48/0x470 >> kthread+0x134/0x160 >> ret_from_fork+0x10/0x1c >> Code: 17ffffaf d503201f f94086c0 91003000 (88dffc00) >> ---[ end trace ccf721c9400ddbd6 ]--- >> Kernel panic - not syncing: Fatal exception >> SMP: stopping secondary CPUs >> Kernel Offset: disabled >> CPU features: 0x090002,24006087 >> Memory Limit: none >> >> ---[ end Kernel panic - not syncing: Fatal exception ]--- >> >> Both issues, the lack of DMA for SPI device and Synchronous abort in I2S >> probe are new after applying this patch. I'm trying to investigate which >> resources are missing and why. The latter issue means typically that the >> registers for the given device has been accessed without enabling the >> needed clocks or power domains. > Did you try this copy-pasta fix that I sent later? > https://lore.kernel.org/lkml/20200517173453.157703-1-saravanak@xxxxxxxxxx/ > > Not every system would need it (my test setup didn't), but it helps some cases. > > If that fix doesn't help, then some tips for debugging the failing drivers. > What this pause/resume patch effectively (not explicitly) does is: > 1. Doesn't immediately probe the devices as they are added in > of_platform_default_populate_init() > 2. Adds them in order to the deferred probe list. > 3. Then kicks off deferred probe on them in the order they were added. > > These drivers are just not handling -EPROBE_DEFER correctly or > assuming probe order and that's causing these issues. > > So, we can either fix that or you can try adding some code to flush > the deferred probe workqueue at the end of fw_devlink_resume(). > > Let me know how it goes. So far it looks that your patch revealed a hidden issue in exynos5433 clocks configuration, because adding clk_ignore_unused parameter to kernel command line fixes the boot. I'm still investigating it, so probable you can ignore my regression report. I will let you know asap I finish checking it. Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland
