[PATCH v2 net] net: stmmac: Use readl_poll_timeout_atomic() in atomic state

[Kevin Hao]

The init_systime() may be invoked in atomic state. We have observed the
following call trace when running "phc_ctl /dev/ptp0 set" on a Intel
Agilex board.
  BUG: sleeping function called from invalid context at drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c:74
  in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 381, name: phc_ctl
  preempt_count: 1, expected: 0
  RCU nest depth: 0, expected: 0
  Preemption disabled at:
  [<ffff80000892ef78>] stmmac_set_time+0x34/0x8c
  CPU: 2 PID: 381 Comm: phc_ctl Not tainted 5.18.0-rc2-next-20220414-yocto-standard+ #567
  Hardware name: SoCFPGA Agilex SoCDK (DT)
  Call trace:
   dump_backtrace.part.0+0xc4/0xd0
   show_stack+0x24/0x40
   dump_stack_lvl+0x7c/0xa0
   dump_stack+0x18/0x34
   __might_resched+0x154/0x1c0
   __might_sleep+0x58/0x90
   init_systime+0x78/0x120
   stmmac_set_time+0x64/0x8c
   ptp_clock_settime+0x60/0x9c
   pc_clock_settime+0x6c/0xc0
   __arm64_sys_clock_settime+0x88/0xf0
   invoke_syscall+0x5c/0x130
   el0_svc_common.constprop.0+0x4c/0x100
   do_el0_svc+0x7c/0xa0
   el0_svc+0x58/0xcc
   el0t_64_sync_handler+0xa4/0x130
   el0t_64_sync+0x18c/0x190

So we should use readl_poll_timeout_atomic() here instead of
readl_poll_timeout().

Also adjust the delay time to 10us to fix a "__bad_udelay" build error
reported by "kernel test robot <lkp at intel.com>". I have tested this on
Intel Agilex and NXP S32G boards, there is no delay needed at all.
So the 10us delay should be long enough for most cases.

Fixes: ff8ed737860e ("net: stmmac: use readl_poll_timeout() function in init_systime()")
Signed-off-by: Kevin Hao <haokexin at gmail.com>
---
v2: Fix the "__bad_udelay" build error.

 drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c
index 22fea0f67245..92d32940aff0 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c
@@ -71,9 +71,9 @@ static int init_systime(void __iomem *ioaddr, u32 sec, u32 nsec)
 	writel(value, ioaddr + PTP_TCR);
 
 	/* wait for present system time initialize to complete */
-	return readl_poll_timeout(ioaddr + PTP_TCR, value,
+	return readl_poll_timeout_atomic(ioaddr + PTP_TCR, value,
 				 !(value & PTP_TCR_TSINIT),
-				 10000, 100000);
+				 10, 100000);
 }
 
 static int config_addend(void __iomem *ioaddr, u32 addend)
-- 
2.34.1