linux-kernel - [PATCH V3 4/9] i2c: xiic: Add wait for FIFO empty in send

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Message-ID: <1674536682-25278-5-git-send-email-manikanta.guntupalli@amd.com>
Date:   Tue, 24 Jan 2023 10:34:37 +0530
From:   Manikanta Guntupalli <manikanta.guntupalli@....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:     <git@....com>, <manikanta.guntupalli@....com>,
        <srinivas.goud@....com>, <shubhrajyoti.datta@....com>,
        <manion05gk@...il.com>,
        Raviteja Narayanam <raviteja.narayanam@...inx.com>
Subject: [PATCH V3 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@....com>
Acked-by: Michal Simek <michal.simek@....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 edc64b79e293..57084696429c 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