linux-kernel - [PATCH] i2c: at91: fix TXRDY interrupt spam

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Date:   Fri, 19 Apr 2019 13:26:53 +0000
From:   Raag Jadav <raag.jadav@...fochips.com>
To:     unlisted-recipients:; (no To-header on input)
CC:     Raag Jadav <raag.jadav@...fochips.com>,
        Ludovic Desroches <ludovic.desroches@...rochip.com>,
        Nicolas Ferre <nicolas.ferre@...rochip.com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: [PATCH] i2c: at91: fix TXRDY interrupt spam

Performing i2c write operation while SDA or SCL line is grounded,
TXRDY interrupt spam hangs the processor, not allowing to boot.

Signed-off-by: raag <raag.jadav@...fochips.com>
---
 drivers/i2c/busses/i2c-at91.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c
index bfd1fdf..47b5e8a 100644
--- a/drivers/i2c/busses/i2c-at91.c
+++ b/drivers/i2c/busses/i2c-at91.c
@@ -270,9 +270,11 @@ static void at91_twi_write_next_byte(struct at91_twi_dev *dev)
 writeb_relaxed(*dev->buf, dev->base + AT91_TWI_THR);

 /* send stop when last byte has been written */
-if (--dev->buf_len == 0)
+if (--dev->buf_len == 0) {
 if (!dev->use_alt_cmd)
 at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP);
+at91_twi_write(dev, AT91_TWI_IDR, AT91_TWI_TXRDY);
+}

 dev_dbg(dev->dev, "wrote 0x%x, to go %zu\n", *dev->buf, dev->buf_len);

--
2.7.4

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