In case of arbitration lost adequate interrupt sometimes is not signaled.
As a result transfer timeouts and is not retried, as it should. To avoid
such cases code is added to check transaction status in case of every
interrupt.
Signed-off-by: Andrzej Hajda <a.hajda@xxxxxxxxxxx>
---
Hi Wolfram,
I have postponed this patch because I was looking for better solution,
but it seems that this patch together with 'disable fifo-almost-empty...'
patch solves the issue of arbitration lost completely.
The patch has been adjusted according to your comment.
Regards
Andrzej
v2:
- replaced switch with if clause,
- commit message fits 75 chars limit.
drivers/i2c/busses/i2c-exynos5.c | 27 ++++++++++++++++++++++++++-
1 file changed, 26 insertions(+), 1 deletion(-)
diff --git a/drivers/i2c/busses/i2c-exynos5.c b/drivers/i2c/busses/i2c-exynos5.c
index 00e81e3..cbd93ce 100644
--- a/drivers/i2c/busses/i2c-exynos5.c
+++ b/drivers/i2c/busses/i2c-exynos5.c
@@ -130,12 +130,32 @@
/* I2C_TRANS_STATUS register bits */
#define HSI2C_MASTER_BUSY (1u << 17)
#define HSI2C_SLAVE_BUSY (1u << 16)
+
+/* I2C_TRANS_STATUS register bits for Exynos5 variant */
#define HSI2C_TIMEOUT_AUTO (1u << 4)
#define HSI2C_NO_DEV (1u << 3)
#define HSI2C_NO_DEV_ACK (1u << 2)
#define HSI2C_TRANS_ABORT (1u << 1)
#define HSI2C_TRANS_DONE (1u << 0)
+/* I2C_TRANS_STATUS register bits for Exynos7 variant */
+#define HSI2C_MASTER_ST_MASK 0xf
+#define HSI2C_MASTER_ST_IDLE 0x0
+#define HSI2C_MASTER_ST_START 0x1
+#define HSI2C_MASTER_ST_RESTART 0x2
+#define HSI2C_MASTER_ST_STOP 0x3
+#define HSI2C_MASTER_ST_MASTER_ID 0x4
+#define HSI2C_MASTER_ST_ADDR0 0x5
+#define HSI2C_MASTER_ST_ADDR1 0x6
+#define HSI2C_MASTER_ST_ADDR2 0x7
+#define HSI2C_MASTER_ST_ADDR_SR 0x8
+#define HSI2C_MASTER_ST_READ 0x9
+#define HSI2C_MASTER_ST_WRITE 0xa
+#define HSI2C_MASTER_ST_NO_ACK 0xb
+#define HSI2C_MASTER_ST_LOSE 0xc
+#define HSI2C_MASTER_ST_WAIT 0xd
+#define HSI2C_MASTER_ST_WAIT_CMD 0xe
+
/* I2C_ADDR register bits */
#define HSI2C_SLV_ADDR_SLV(x) ((x & 0x3ff) << 0)
#define HSI2C_SLV_ADDR_MAS(x) ((x & 0x3ff) << 10)
@@ -437,6 +457,7 @@ static irqreturn_t exynos5_i2c_irq(int irqno, void *dev_id)
int_status = readl(i2c->regs + HSI2C_INT_STATUS);
writel(int_status, i2c->regs + HSI2C_INT_STATUS);
+ trans_status = readl(i2c->regs + HSI2C_TRANS_STATUS);
/* handle interrupt related to the transfer status */
if (i2c->variant->hw == HSI2C_EXYNOS7) {
@@ -460,8 +481,12 @@ static irqreturn_t exynos5_i2c_irq(int irqno, void *dev_id)
i2c->state = -ETIMEDOUT;
goto stop;
}
+
+ if ((trans_status & HSI2C_MASTER_ST_MASK) == HSI2C_MASTER_ST_LOSE) {
+ i2c->state = -EAGAIN;
+ goto stop;
+ }
} else if (int_status & HSI2C_INT_I2C) {
- trans_status = readl(i2c->regs + HSI2C_TRANS_STATUS);
if (trans_status & HSI2C_NO_DEV_ACK) {
dev_dbg(i2c->dev, "No ACK from device\n");
i2c->state = -ENXIO;
--
2.7.4
--
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