From c4d936efa46d8ea183df16c0f3fa4423327da51d Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: Fri, 17 Dec 2021 16:24:30 +0100
Subject: [PATCH] Revert "usb: early: convert to readl_poll_timeout_atomic()"

This reverts commit 796eed4b2342c9d6b26c958e92af91253a2390e1.

This change causes boot lockups when using "arlyprintk=xdbc" because
ktime can not be used at this point in time in the boot process.  Also,
it is not needed for very small delays like this.

Reported-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Reported-by: Peter Zijlstra <peterz@infradead.org>
Cc: Jann Horn <jannh@google.com>
Cc: Chunfeng Yun <chunfeng.yun@mediatek.com>
Fixes: 796eed4b2342 ("usb: early: convert to readl_poll_timeout_atomic()")
Link: https://lore.kernel.org/r/c2b5c9bb-1b75-bf56-3754-b5b18812d65e@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/usb/early/xhci-dbc.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index 933d77ad0a64..4502108069cd 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -14,7 +14,6 @@
 #include <linux/pci_ids.h>
 #include <linux/memblock.h>
 #include <linux/io.h>
-#include <linux/iopoll.h>
 #include <asm/pci-direct.h>
 #include <asm/fixmap.h>
 #include <linux/bcd.h>
@@ -136,9 +135,17 @@ static int handshake(void __iomem *ptr, u32 mask, u32 done, int wait, int delay)
 {
 	u32 result;
 
-	return readl_poll_timeout_atomic(ptr, result,
-					 ((result & mask) == done),
-					 delay, wait);
+	/* Can not use readl_poll_timeout_atomic() for early boot things */
+	do {
+		result = readl(ptr);
+		result &= mask;
+		if (result == done)
+			return 0;
+		udelay(delay);
+		wait -= delay;
+	} while (wait > 0);
+
+	return -ETIMEDOUT;
 }
 
 static void __init xdbc_bios_handoff(void)
-- 
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