Hi Ming, >>>>> We've received a number of reports of warnings when coming >>>>> out of suspend with certain bluetooth firmware configurations: >>>>> >>>>> WARNING: CPU: 3 PID: 3280 at drivers/base/firmware_class.c:1126 >>>>> _request_firmware+0x558/0x810() >>>>> Modules linked in: ccm ip6t_rpfilter ip6t_REJECT nf_reject_ipv6 >>>>> xt_conntrack ebtable_nat ebtable_broute bridge stp llc ebtable_filter >>>>> ebtables ip6table_nat nf_conntrack_ipv6 nf_defrag_ipv6 nf_nat_ipv6 >>>>> ip6table_mangle ip6table_security ip6table_raw ip6table_filter >>>>> ip6_tables iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 >>>>> nf_nat nf_conntrack iptable_mangle iptable_security iptable_raw >>>>> binfmt_misc bnep intel_rapl iosf_mbi arc4 x86_pkg_temp_thermal >>>>> snd_hda_codec_hdmi coretemp kvm_intel joydev snd_hda_codec_realtek >>>>> iwldvm snd_hda_codec_generic kvm iTCO_wdt mac80211 iTCO_vendor_support >>>>> snd_hda_intel snd_hda_controller snd_hda_codec crct10dif_pclmul >>>>> snd_hwdep crc32_pclmul snd_seq crc32c_intel ghash_clmulni_intel uvcvideo >>>>> snd_seq_device iwlwifi btusb videobuf2_vmalloc snd_pcm videobuf2_core >>>>> serio_raw bluetooth cfg80211 videobuf2_memops sdhci_pci v4l2_common >>>>> videodev thinkpad_acpi sdhci i2c_i801 lpc_ich mfd_core wacom mmc_core >>>>> media snd_timer tpm_tis hid_logitech_hidpp wmi tpm rfkill snd mei_me mei >>>>> shpchp soundcore nfsd auth_rpcgss nfs_acl lockd grace sunrpc i915 >>>>> i2c_algo_bit drm_kms_helper e1000e drm hid_logitech_dj ptp pps_core >>>>> video >>>>> CPU: 3 PID: 3280 Comm: kworker/u17:0 Not tainted 3.19.3-200.fc21.x86_64 >>>>> Hardware name: LENOVO 343522U/343522U, BIOS GCET96WW (2.56 ) 10/22/2013 >>>>> Workqueue: hci0 hci_power_on [bluetooth] >>>>> 0000000000000000 0000000089944328 ffff88040acffb78 ffffffff8176e215 >>>>> 0000000000000000 0000000000000000 ffff88040acffbb8 ffffffff8109bc1a >>>>> 0000000000000000 ffff88040acffcd0 00000000fffffff5 ffff8804076bac40 >>>>> Call Trace: >>>>> [<ffffffff8176e215>] dump_stack+0x45/0x57 >>>>> [<ffffffff8109bc1a>] warn_slowpath_common+0x8a/0xc0 >>>>> [<ffffffff8109bd4a>] warn_slowpath_null+0x1a/0x20 >>>>> [<ffffffff814dbe78>] _request_firmware+0x558/0x810 >>>>> [<ffffffff814dc165>] request_firmware+0x35/0x50 >>>>> [<ffffffffa03a7886>] btusb_setup_bcm_patchram+0x86/0x590 [btusb] >>>>> [<ffffffff814d40e6>] ? rpm_idle+0xd6/0x230 >>>>> [<ffffffffa04d4801>] hci_dev_do_open+0xe1/0xa90 [bluetooth] >>>>> [<ffffffff810c51dd>] ? ttwu_do_activate.constprop.90+0x5d/0x70 >>>>> [<ffffffffa04d5980>] hci_power_on+0x40/0x200 [bluetooth] >>>>> [<ffffffff810b487c>] process_one_work+0x14c/0x3f0 >>>>> [<ffffffff810b52f3>] worker_thread+0x53/0x470 >>>>> [<ffffffff810b52a0>] ? rescuer_thread+0x300/0x300 >>>>> [<ffffffff810ba548>] kthread+0xd8/0xf0 >>>>> [<ffffffff810ba470>] ? kthread_create_on_node+0x1b0/0x1b0 >>>>> [<ffffffff81774958>] ret_from_fork+0x58/0x90 >>>>> [<ffffffff810ba470>] ? kthread_create_on_node+0x1b0/0x1b0 >>>>> >>>>> This occurs after every resume. >>>>> >>>>> When resuming, the bluetooth driver needs to re-request the >>>>> firmware. This re-request is happening before usermodehelper >>>>> is fully enabled. If the firmware load succeeded previously, the >>>>> caching behavior of the firmware code typically negates the >>>>> need to call the usermodehelper code again and the request >>>>> succeeds. If the firmware was never loaded because it isn't >>>>> actually present in the file system, this results in a call >>>>> to usermodehelper and a failure warning every resume. Rather >>>>> than have a WARN clogging up the kernel messages each time, >>>>> just drop the warn. There is still a dev_err for debugging >>>>> purposes. >>>>> >>>>> Signed-off-by: Laura Abbott <[email protected]> >>>>> --- >>>>> This might be papering over a real issue but I'm not >>>>> familiar enough with any of suspend/resume, bluetooth, >>>>> or firmware loading to identify an alternate fix. >>>>> The backtrace is from bcm patchram but the problem >>>>> isn't limited to that hardware. Intel also does a >>>>> request firmware and I was able to reproduce the >>>>> same backtrace on that driver by requesting non-existant >>>>> firmware file. >>>> >>>> so here is the thing with Bluetooth firmware. Some of them >>>> are RAM patches to fix the ROM modules. Others are full firmware >>>> that are required to be downloaded first. >>>> >>>> For ROM modules, the RAM patching procedure is optional. So we >>>> will proceed even if no firmware is available. This means that >>>> the kernel will never cache it (since it is not there in the >>>> first place) and also on every resume we have the same issues. >>>> So optional firmware is something that happens for Bluetooth USB >>>> dongles a lot. >>>> >>>> In the driver we know which firmwares are optional and which are >>>> required. So we could tell the firmware class this if this would make >>>> things better and result in clearer errors and warnings. Is that >>>> something we want here? >>>> >>> >>> The response on another reply was >>> >>> "Yes, it is a driver problem, and loading firmware from filesystem >>> isn't safe during resume, and that is the purpose of the warning." >>> >>> It isn't clear if this means request_firmware shouldn't be called >>> on resume at all or if request_firmware shouldn't be called unless >>> we can guarantee it won't make a call into the file system. I'd > > If the firmware is cached before resume, it is ok to call request_firmware() > during resume. Otherwise it will call filesystem and disks, which may > be a problem because the disk may not be ready for completing the > request during resume. > >>> be okay with adding another api (request_optional_firmware?) to >>> represent this if the firmware maintainers aren't against the >>> concept. If the firmware maintainers are against the concept, >>> it seems like the only solution is to rework the bluetooth drivers >>> to not request anything on resume. > > So do you just want to work around the warning by introducing a new > API? > >> >> I think request_optional_firmware concept sounds like an useful addition. >> >> However the problem here is that the driver does not know that it is called >> from resume path. It is easy to say that this is a driver problem, but the >> driver does not know it. > > From USB stack view, one usb driver should know it is in the resume path > because the root entry is the .resume() callback of the USB BT driver.
have you actually read drivers/bluetooth/btusb.c before making these statements. I explained how and when request_firmware is actually called. >> If the hci_register_dev is called which in fact triggers hdev->setup to deal >> with vendor specific firmware path, then it means the driver just went >> through its probe() phase again. How would the driver differentiate this >> from any hot plug event. So to say this is a driver problem is just plain >> stupid. The driver does not know we are ending up in a reset_resume use case >> or when ACPI/BIOS decides to emulate an USB disconnect. The only time request_firmware is called is from hdev->setup(). And that can only be triggered by hci_register_dev(). Which is only called from probe() callback of the driver. This has nothing to do with the resume() callback. Regards Marcel -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
