i2c: imx-lpi2c: directly return ISR when detect a NACK

A NACK flag in ISR means i2c bus error. In such condition,
there is no need to do read/write operation.

In this patch, i2c will check MSR_NDF, MSR_RDF and MSR_TDF
flag in turn, it's making mutually exclusive NACK/read/write.
So when a NACK is received(MSR_NDF), i2c will return ISR
directly and then stop i2c transfer.

Signed-off-by: Carlos Song <carlos.song@nxp.com>
Reviewed-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20230727030347.3552992-1-carlos.song@nxp.com
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>

diff --git a/drivers/i2c/busses/i2c-imx-lpi2c.c b/drivers/i2c/busses/i2c-imx-lpi2c.c
index c3287c8..636ad32 100644 (file)
--- a/drivers/i2c/busses/i2c-imx-lpi2c.c
+++ b/drivers/i2c/busses/i2c-imx-lpi2c.c
@@ -514,14 +514,12 @@ static irqreturn_t lpi2c_imx_isr(int irq, void *dev_id)
        temp = readl(lpi2c_imx->base + LPI2C_MSR);
        temp &= enabled;
 
-       if (temp & MSR_RDF)
-               lpi2c_imx_read_rxfifo(lpi2c_imx);
-
-       if (temp & MSR_TDF)
-               lpi2c_imx_write_txfifo(lpi2c_imx);
-
        if (temp & MSR_NDF)
                complete(&lpi2c_imx->complete);
+       else if (temp & MSR_RDF)
+               lpi2c_imx_read_rxfifo(lpi2c_imx);
+       else if (temp & MSR_TDF)
+               lpi2c_imx_write_txfifo(lpi2c_imx);
 
        return IRQ_HANDLED;
 }