From 1e2233d4f3dfdad501134f685caab9e936675387 Mon Sep 17 00:00:00 2001 From: Eddie James Date: Thu, 11 Feb 2021 13:48:46 -0600 Subject: fsi: Aspeed: Reduce poll timeout The lengthy timeout previously used sometimes resulted in scheduling problems, detailed below. Therefore reduce the timeout to 500us. This timeout selection is supported by the benchmarks collected below with various clock dividers. This is purely the time spent polling (reported by ktime_get()). div 1: max:150us avg: 2us div 2: max:155us avg: 3us div 4: max:149us avg: 7us div 8: max:153us avg: 13us div 16: max:197us avg: 21us div 32: max:181us avg: 50us div 64: max:262us avg:100us Jan 22 01:27:21 rain27bmc kernel: rcu: INFO: rcu_sched self-detected stall on CPU Jan 22 01:27:21 rain27bmc kernel: rcu: 0-....: (2099 ticks this GP) idle=0ca/1/0x40000002 softirq=349573/349573 fqs=1048 Jan 22 01:27:21 rain27bmc kernel: (t=2100 jiffies g=841149 q=7163) Jan 22 01:27:21 rain27bmc kernel: NMI backtrace for cpu 0 Jan 22 01:27:21 rain27bmc kernel: CPU: 0 PID: 5959 Comm: ibm-read-vpd Not tainted 5.8.17-a9b4ea8 #1 Jan 22 01:27:21 rain27bmc kernel: Hardware name: Generic DT based system Jan 22 01:27:21 rain27bmc kernel: Backtrace: Jan 22 01:27:25 rain27bmc kernel: [<8010d92c>] (dump_backtrace) from [<8010db80>] (show_stack+0x20/0x24) ... Jan 22 01:27:25 rain27bmc kernel: [<8010130c>] (gic_handle_irq) from [<80100b0c>] (__irq_svc+0x6c/0x90) Jan 22 01:27:25 rain27bmc kernel: Exception stack(0xb79159b0 to 0xb79159f8) Jan 22 01:27:25 rain27bmc kernel: 59a0: 9e88e5d5 00000559 00000559 00000018 Jan 22 01:27:25 rain27bmc kernel: 59c0: 00000000 9f217c55 00000003 00000559 a0201c00 bfa4d048 bfa4d000 b7915a44 Jan 22 01:27:25 rain27bmc kernel: 59e0: 40e88f8a b7915a00 3254e553 80734924 80030113 ffffffff Jan 22 01:27:25 rain27bmc kernel: r9:b7914000 r8:a0201c00 r7:b79159e4 r6:ffffffff r5:80030113 r4:80734924 Jan 22 01:27:25 rain27bmc kernel: [<807348b4>] (__opb_read) from [<80734d98>] (aspeed_master_read+0xbc/0xcc) Jan 22 01:27:25 rain27bmc kernel: r10:00000004 r9:00000002 r8:80734cdc r7:bd33fa40 r6:00000004 r5:bd33f840 Jan 22 01:27:25 rain27bmc kernel: r4:00201c00 Jan 22 01:27:25 rain27bmc kernel: [<80734cdc>] (aspeed_master_read) from [<807320f0>] (fsi_master_read+0x6c/0x1bc) ... Signed-off-by: Eddie James Link: https://lore.kernel.org/r/20210211194846.35475-1-eajames@linux.ibm.com Signed-off-by: Joel Stanley --- drivers/fsi/fsi-master-aspeed.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/fsi') diff --git a/drivers/fsi/fsi-master-aspeed.c b/drivers/fsi/fsi-master-aspeed.c index d3ffa8423dea..8606e55c1721 100644 --- a/drivers/fsi/fsi-master-aspeed.c +++ b/drivers/fsi/fsi-master-aspeed.c @@ -92,7 +92,7 @@ static const u32 fsi_base = 0xa0000000; static u16 aspeed_fsi_divisor = FSI_DIVISOR_DEFAULT; module_param_named(bus_div,aspeed_fsi_divisor, ushort, 0); -#define OPB_POLL_TIMEOUT 10000 +#define OPB_POLL_TIMEOUT 500 static int __opb_write(struct fsi_master_aspeed *aspeed, u32 addr, u32 val, u32 transfer_size) -- cgit v1.2.3