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Subject[PATCH v2 2/3] i2c: imx: Check for I2SR_IAL after every byte
Date
Arbitration Lost (IAL) can happen after every single byte transfer. If
arbitration is lost, the I2C hardware will autonomously switch from
master mode to slave. If a transfer is not aborted in this state,
consecutive transfers will not be executed by the hardware and will
timeout.

Signed-off-by: Christian Eggers <ceggers@arri.de>
Cc: stable@vger.kernel.org
---
drivers/i2c/busses/i2c-imx.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 34648df7f1a6..1db1e2f5296e 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -483,6 +483,24 @@ static int i2c_imx_trx_complete(struct imx_i2c_struct *i2c_imx, bool atomic)
dev_dbg(&i2c_imx->adapter.dev, "<%s> Timeout\n", __func__);
return -ETIMEDOUT;
}
+
+ /* check for arbitration lost */
+ if (i2c_imx->i2csr & I2SR_IAL) {
+ unsigned int temp;
+
+ dev_dbg(&i2c_imx->adapter.dev, "<%s> Arbitration lost\n", __func__);
+ /*
+ * i2sr_clr_opcode is the value to clear all interrupts.
+ * Here we want to clear only I2SR_IAL, so we write
+ * ~i2sr_clr_opcode with just the I2SR_IAL bit toggled.
+ */
+ temp = ~i2c_imx->hwdata->i2sr_clr_opcode ^ I2SR_IAL;
+ imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2SR);
+
+ i2c_imx->i2csr = 0;
+ return -EAGAIN;
+ }
+
dev_dbg(&i2c_imx->adapter.dev, "<%s> TRX complete\n", __func__);
i2c_imx->i2csr = 0;
return 0;
--
Christian Eggers
Embedded software developer
Arnold & Richter Cine Technik GmbH & Co. Betriebs KG
Sitz: Muenchen - Registergericht: Amtsgericht Muenchen - Handelsregisternummer: HRA 57918
Persoenlich haftender Gesellschafter: Arnold & Richter Cine Technik GmbH
Sitz: Muenchen - Registergericht: Amtsgericht Muenchen - Handelsregisternummer: HRB 54477
Geschaeftsfuehrer: Dr. Michael Neuhaeuser; Stephan Schenk; Walter Trauninger; Markus Zeiler

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