linux-kernel - [PATCH V2 4/9] i2c: xiic: Add wait for FIFO empty in send

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Date:   Thu, 22 Sep 2022 14:14:49 +0530
From:   Manikanta Guntupalli <manikanta.guntupalli@...inx.com>
To:     <michal.simek@...inx.com>, <michal.simek@....com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-i2c@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:     <radhey.shyam.pandey@....com>, <srinivas.goud@....com>,
        <shubhrajyoti.datta@....com>,
        Raviteja Narayanam <raviteja.narayanam@...inx.com>,
        Manikanta Guntupalli <manikanta.guntupalli@...inx.com>
Subject: [PATCH V2 4/9] i2c: xiic: Add wait for FIFO empty in send_tx

From: Raviteja Narayanam <raviteja.narayanam@...inx.com>

If the tx_half_empty interrupt comes first instead of tx_empty,
STOP bit is generated even before all the bytes are transmitted
out on the bus.
STOP bit should be sent only after all the bytes in the FIFO are
transmitted out of the FIFO. So wait until FIFO is empty before sending
the STOP bit.

Signed-off-by: Raviteja Narayanam <raviteja.narayanam@...inx.com>
Signed-off-by: Manikanta Guntupalli <manikanta.guntupalli@...inx.com>
---
 drivers/i2c/busses/i2c-xiic.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/i2c/busses/i2c-xiic.c b/drivers/i2c/busses/i2c-xiic.c
index 10e0fafb25f1..1149104074a7 100644
--- a/drivers/i2c/busses/i2c-xiic.c
+++ b/drivers/i2c/busses/i2c-xiic.c
@@ -436,6 +436,13 @@ static void xiic_fill_tx_fifo(struct xiic_i2c *i2c)
 				data |= XIIC_TX_DYN_STOP_MASK;
 			} else {
 				u8 cr;
+				int status;
+
+				/* Wait till FIFO is empty so STOP is sent last */
+				status = xiic_wait_tx_empty(i2c);
+				if (status)
+					return;
+
 				/* Write to CR to stop */
 				cr = xiic_getreg8(i2c, XIIC_CR_REG_OFFSET);
 				xiic_setreg8(i2c, XIIC_CR_REG_OFFSET, cr &
-- 
2.25.1