On Tue, 23 Mar 2021 at 15:00, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote: > > On Tue, 23 Mar 2021 at 11:49, hieagle <chgokhl@xxxxxxxxx> wrote: > > > > We encounter a resume issue in our device sometimes. The mmc device's > > parent list is > > mmc0:0001->mmc_host mmc0->fa630000.mmc->soc in our soc. We found in the blow > > case with mmc0->power.disable_depth=0 the mmc_runtime_resume will be skipped, > > which cause subsequent mmc command fail. > > > > mmc_get_card(mmc0:0001)->pm_runtime_get_sync->rpm_resume(mmc0:0001)->rpm_resume(mmc0) > > The rpm_resume(mmc0) return -ENOSYS due to no callback and > > mmc0->power.runtime_status > > keep RPM_SUSPENDED. This lead to rpm_resume(mmc0:0001) return -EBUSY and skip > > rpm_callback which call mmc_runtime_resume, the mmc is still in > > suspended and the > > subsequent mmc command fail. > > > > [ 198.856157] Call trace: > > [ 198.858917] [<ffffff800808bd9c>] dump_backtrace+0x0/0x1cc > > [ 198.864966] [<ffffff800808bf7c>] show_stack+0x14/0x1c > > [ 198.870627] [<ffffff8008400e88>] dump_stack+0xa8/0xe0 > > [ 198.876288] [<ffffff800854d38c>] rpm_resume+0x850/0x938 > > [ 198.882141] [<ffffff800854cd8c>] rpm_resume+0x250/0x938 > > [ 198.887994] [<ffffff800854d4c4>] __pm_runtime_resume+0x50/0x74 > > [ 198.894530] [<ffffff80087b9e64>] mmc_get_card+0x3c/0xb8 > > [ 198.900388] [<ffffff80087cd2e0>] mmc_blk_issue_rq+0x2b0/0x4d8 > > [ 198.906824] [<ffffff80087cd5e4>] mmc_queue_thread+0xdc/0x198 > > [ 198.913165] [<ffffff80080d4b2c>] kthread+0xec/0x100 > > [ 198.918632] [<ffffff8008083890>] ret_from_fork+0x10/0x40 > > [ 198.924582] mmc0 callback (null) > > [ 198.935837] mmcblk mmc0:0001: __pm_runtime_resume ret -16 > > > > Mark mmc_host device with pm_runtime_no_callbacks will solve the issue. > > Thanks. > > Huanlin Ke So I have looked a bit closer to this, finally. Apologies for the delay. If I am not mistaken, rpm_resume() should *not* be called recursively for a device's parent, unless the parent's ->power.disable_depth has been decremented to zero. No matter if we have called pm_runtime_no_callbacks() for the child device or not. In the scenario you describe, the parent device corresponds to the mmc class device (initialized in mmc_alloc_host()). Since the mmc core never calls pm_runtime_enable() for it, its - >power.disable_depth should always remain greater than 0. Although, I admit, the code in runtime.c isn't that easy to browse, so I may be wrong. That said, I fail to see how -ENOSYS can be returned rpm_resume() in the path you describe. Would it be possible for you to provide more logs to show this? Or could it be that you have a patch locally that calls pm_runtime_enable() for the mmc class device, somewhere? That would also explains things? :-) [...] > > > > > > On Sat, 20 Mar 2021 at 05:57, kehuanlin <chgokhl@xxxxxxxxx> wrote: > > > > > > > > The rpm_resume() will call parent's resume callback recursively. > > > > Since mmc_host has no its own pm_runtime callbacks, the mmc devices > > > > may fail to resume (-ENOSYS in rpm_callback) sometimes. Mark mmc_host > > > > device with pm_runtime_no_callbacks can fix the issue. > > > > > > Can you please elaborate more on this? What do you mean by "sometimes"? > > > > > > More precisely, how do you trigger the rpm_callback() for mmc class > > > device to return -ENOSYS? > > > > > > Don't get me wrong, the patch is fine, but I want to understand if it > > > actually solves a problem for you - or that it's better considered as > > > an optimization? > > > > > > Kind regards > > > Uffe > > > > > > > > > > > Signed-off-by: kehuanlin <chgokhl@xxxxxxxxx> > > > > --- > > > > drivers/mmc/core/host.c | 2 ++ > > > > 1 file changed, 2 insertions(+) > > > > > > > > diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c > > > > index 9b89a91b6b47..177bebd9a6c4 100644 > > > > --- a/drivers/mmc/core/host.c > > > > +++ b/drivers/mmc/core/host.c > > > > @@ -15,6 +15,7 @@ > > > > #include <linux/of.h> > > > > #include <linux/of_gpio.h> > > > > #include <linux/pagemap.h> > > > > +#include <linux/pm_runtime.h> > > > > #include <linux/pm_wakeup.h> > > > > #include <linux/export.h> > > > > #include <linux/leds.h> > > > > @@ -480,6 +481,7 @@ struct mmc_host *mmc_alloc_host(int extra, struct device *dev) > > > > host->class_dev.class = &mmc_host_class; > > > > device_initialize(&host->class_dev); > > > > device_enable_async_suspend(&host->class_dev); > > > > + pm_runtime_no_callbacks(&host->class_dev); > > > > > > > > if (mmc_gpio_alloc(host)) { > > > > put_device(&host->class_dev); > > > > -- > > > > 2.30.0 > > > > Kind regards Uffe