linux-kernel - [PATCH AUTOSEL 6.2 10/25] i2c: hisi: Avoid redundant interrupts

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Date:   Fri, 31 Mar 2023 21:41:08 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Yicong Yang <yangyicong@...ilicon.com>,
        Sheng Feng <fengsheng5@...wei.com>,
        Wolfram Sang <wsa@...nel.org>, Sasha Levin <sashal@...nel.org>,
        linux-i2c@...r.kernel.org
Subject: [PATCH AUTOSEL 6.2 10/25] i2c: hisi: Avoid redundant interrupts

From: Yicong Yang <yangyicong@...ilicon.com>

[ Upstream commit cc9812a3096d1986caca9a23bee99effc45c08df ]

After issuing all the messages we can disable the TX_EMPTY interrupts
to avoid handling redundant interrupts. For doing a sinlge bus
detection (i2cdetect -y -r 0) we can reduce ~97% interrupts (before
~12000 after ~400).

Signed-off-by: Sheng Feng <fengsheng5@...wei.com>
Signed-off-by: Yicong Yang <yangyicong@...ilicon.com>
Signed-off-by: Wolfram Sang <wsa@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/i2c/busses/i2c-hisi.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/i2c/busses/i2c-hisi.c b/drivers/i2c/busses/i2c-hisi.c
index f5c37d2f536bc..e067671b3ce2e 100644
--- a/drivers/i2c/busses/i2c-hisi.c
+++ b/drivers/i2c/busses/i2c-hisi.c
@@ -316,6 +316,13 @@ static void hisi_i2c_xfer_msg(struct hisi_i2c_controller *ctlr)
 		    max_write == 0)
 			break;
 	}
+
+	/*
+	 * Disable the TX_EMPTY interrupt after finishing all the messages to
+	 * avoid overwhelming the CPU.
+	 */
+	if (ctlr->msg_tx_idx == ctlr->msg_num)
+		hisi_i2c_disable_int(ctlr, HISI_I2C_INT_TX_EMPTY);
 }
 
 static irqreturn_t hisi_i2c_irq(int irq, void *context)
-- 
2.39.2