linux-kernel - [V2] i2c: i2c-qcom-geni: Correct I2C TRE sequence

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Message-Id: <20240129061003.4085-1-quic_vdadhani@quicinc.com>
Date: Mon, 29 Jan 2024 11:40:03 +0530
From: Viken Dadhaniya <quic_vdadhani@...cinc.com>
To: andersson@...nel.org, konrad.dybcio@...aro.org, andi.shyti@...nel.org,
        linux-arm-msm@...r.kernel.org, linux-i2c@...r.kernel.org,
        linux-kernel@...r.kernel.org, vkoul@...nel.org,
        quic_bjorande@...cinc.com, manivannan.sadhasivam@...aro.org
Cc: quic_msavaliy@...cinc.com, quic_vtanuku@...cinc.com,
        Viken Dadhaniya <quic_vdadhani@...cinc.com>
Subject: [V2] i2c: i2c-qcom-geni: Correct I2C TRE sequence

For i2c read operation, we are getting gsi mode timeout due
to malformed TRE(Transfer Ring Element). Currently we are
configuring incorrect TRE sequence in gpi driver
(drivers/dma/qcom/gpi.c) as below

- Sets up CONFIG
- Sets up DMA tre
- Sets up GO tre

As per HPG(Hardware programming guide), We should configure TREs in below
sequence for any i2c transfer

- Sets up CONFIG tre
- Sets up GO tre
- Sets up DMA tre

For only write operation or write followed by read operation,
existing software sequence is correct.

for only read operation, TRE sequence need to be corrected.
Hence, we have changed the sequence to submit GO tre before DMA tre.

Tested covering i2c read/write transfer on QCM6490 RB3 board.

Signed-off-by: Viken Dadhaniya <quic_vdadhani@...cinc.com>
Fixes: commit d8703554f4de ("i2c: qcom-geni: Add support for GPI DMA")
---
v1 -> v2:
- Remove redundant check.
- update commit log.
- add fix tag.
---
---
 drivers/i2c/busses/i2c-qcom-geni.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/i2c/busses/i2c-qcom-geni.c b/drivers/i2c/busses/i2c-qcom-geni.c
index 0d2e7171e3a6..da94df466e83 100644
--- a/drivers/i2c/busses/i2c-qcom-geni.c
+++ b/drivers/i2c/busses/i2c-qcom-geni.c
@@ -613,20 +613,20 @@ static int geni_i2c_gpi_xfer(struct geni_i2c_dev *gi2c, struct i2c_msg msgs[], i
 
 		peripheral.addr = msgs[i].addr;
 
+		ret =  geni_i2c_gpi(gi2c, &msgs[i], &config,
+				    &tx_addr, &tx_buf, I2C_WRITE, gi2c->tx_c);
+		if (ret)
+			goto err;
+
 		if (msgs[i].flags & I2C_M_RD) {
 			ret =  geni_i2c_gpi(gi2c, &msgs[i], &config,
 					    &rx_addr, &rx_buf, I2C_READ, gi2c->rx_c);
 			if (ret)
 				goto err;
-		}
-
-		ret =  geni_i2c_gpi(gi2c, &msgs[i], &config,
-				    &tx_addr, &tx_buf, I2C_WRITE, gi2c->tx_c);
-		if (ret)
-			goto err;
 
-		if (msgs[i].flags & I2C_M_RD)
 			dma_async_issue_pending(gi2c->rx_c);
+		}
+
 		dma_async_issue_pending(gi2c->tx_c);
 
 		timeout = wait_for_completion_timeout(&gi2c->done, XFER_TIMEOUT);
-- 
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