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Date: Wed, 1 Mar 2017 16:03:15 +0530
From: Aishwarya Pant <aishpant@gmail.com>
To: Lidza Louina <lidza.louina@gmail.com>,
	Mark Hounschell <markh@compro.net>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: outreachy-kernel@googlegroups.com
Subject: [PATCH v3] staging: dgnc: replace usleep_range with udelay
Message-ID: <20170301103315.GA4448@aishwarya>
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udelay is impelmented using a busy-wait loop and consumes CPU cycles
while usleep_range is implemented using interrupts.cls_flush_uart_write()
is called after a channel lock is acquired i.e. an atomic context.
Hence delay in this method should use udelay instead of usleep_range.

Signed-off-by: Aishwarya Pant <aishpant@gmail.com>

---
Changes in v3:
	- Add a comment in code udelay to ignore checkpatch warning
Changes in v2:
	- Edit commit message to explain why udelay should be used

 drivers/staging/dgnc/dgnc_cls.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/dgnc/dgnc_cls.c b/drivers/staging/dgnc/dgnc_cls.c
index 28a3e16..ec190e5 100644
--- a/drivers/staging/dgnc/dgnc_cls.c
+++ b/drivers/staging/dgnc/dgnc_cls.c
@@ -609,7 +609,11 @@ static void cls_flush_uart_write(struct channel_t *ch)
 
 	writeb((UART_FCR_ENABLE_FIFO | UART_FCR_CLEAR_XMIT),
 	       &ch->ch_cls_uart->isr_fcr);
-	usleep_range(10, 20);
+
+	/* Ignore checkpatch warning to replace udelay by usleep_range
+	 * as this function is called under an atomic context
+	 */
+	udelay(10);
 
 	ch->ch_flags |= (CH_TX_FIFO_EMPTY | CH_TX_FIFO_LWM);
 }
-- 
2.7.4