Hi all,
we have encountered CPU stalls in mainline kernel while loading the
bluetooth module. We have custom board based on rockchip rv1109 soc
and there is bluetooth chipset of relatek 8821cs. CPU is stalls while
realtek 8821cs module.
Bug/Regression:
In current mainline, we found CPU is stalls when we load bluetooth
module. git bisect shows commit 22a9d9585812440211b0b34a6bc02ade62314be4
as a bad, which produce CPU stalls.
git show 22a9d9585812440211b0b34a6bc02ade62314be4
commit 22a9d9585812440211b0b34a6bc02ade62314be4
Author: Bumyong Lee <bumyong.lee@xxxxxxxxxxx>
Date: Tue Dec 19 14:50:26 2023 +0900
dmaengine: pl330: issue_pending waits until WFP state
According to DMA-330 errata notice[1] 71930, DMAKILL
cannot clear internal signal, named pipeline_req_active.
it makes that pl330 would wait forever in WFP state
although dma already send dma request if pl330 gets
dma request before entering WFP state.
The errata suggests that polling until entering WFP state
as workaround and then peripherals allows to issue dma request.
[1]: https://developer.arm.com/documentation/genc008428/latest
Signed-off-by: Bumyong Lee <bumyong.lee@xxxxxxxxxxx>
Link:
https://lore.kernel.org/r/20231219055026.118695-1-bumyong.lee@xxxxxxxxxxx
Signed-off-by: Vinod Koul <vkoul@xxxxxxxxxx>
diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c
index 3cf0b38387ae..c29744bfdf2c 100644
--- a/drivers/dma/pl330.c
+++ b/drivers/dma/pl330.c
@@ -1053,6 +1053,9 @@ static bool _trigger(struct pl330_thread *thrd)
thrd->req_running = idx;
+ if (desc->rqtype == DMA_MEM_TO_DEV || desc->rqtype ==
DMA_DEV_TO_MEM)
+ UNTIL(thrd, PL330_STATE_WFP);
+
return true;
}
By reverting this commit, we have success in loading of bluetooth module.
Output of CPU stalls:
# modprobe hci_uart
[ 27.024749] Bluetooth: HCI UART driver ver 2.3
[ 27.025284] Bluetooth: HCI UART protocol Three-wire (H5) registered
# [ 28.125338] dwmmc_rockchip ffc70000.mmc: Unexpected interrupt latency
[ 33.245339] dwmmc_rockchip ffc50000.mmc: Unexpected interrupt latency
[ 326.195321] rcu: INFO: rcu_sched detected stalls on CPUs/tasks:
[ 326.195880] rcu: 0-...0: (3 ticks this GP) idle=e5f4/1/0x40000000
softirq=551/552 fqs=420
[ 326.196621] rcu: hardirqs softirqs csw/system
[ 326.197115] rcu: number: 0 0 0
[ 326.197612] rcu: cputime: 0 0 0 ==>
10500(ms)
[ 326.198231] rcu: (detected by 1, t=2105 jiffies, g=-455, q=17
ncpus=2)
[ 326.198823] Sending NMI from CPU 1 to CPUs 0:
Expected Output:
# modprobe hci_uart
[ 30.690321] Bluetooth: HCI UART driver ver 2.3
[ 30.690852] Bluetooth: HCI UART protocol Three-wire (H5) registered
# [ 31.453586] Bluetooth: hci0: RTL: examining hci_ver=08 hci_rev=000c
lmp_ver=08 lmp_subver=8821
[ 31.458061] Bluetooth: hci0: RTL: rom_version status=0 version=1
[ 31.458608] Bluetooth: hci0: RTL: loading rtl_bt/rtl8821cs_fw.bin
[ 31.465029] Bluetooth: hci0: RTL: loading rtl_bt/rtl8821cs_config.bin
[ 31.483926] Bluetooth: hci0: RTL: cfg_sz 25, total sz 36953
[ 32.213105] Bluetooth: hci0: RTL: fw version 0x75b8f098
[ 32.274216] Bluetooth: MGMT ver 1.22
[ 32.285376] NET: Registered PF_ALG protocol family
Thanks,
Karthikeyan K
