linux-kernel - [PATCH] i2c: qcom-geni: Fix GPI DMA buffer sync-back

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Message-Id: <20220807140455.409417-1-robin.reckmann@gmail.com>
Date:   Sun,  7 Aug 2022 23:04:54 +0900
From:   Robin Reckmann <robin.reckmann@...glemail.com>
To:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Christian König <christian.koenig@....com>
Cc:     Robin Reckmann <robin.reckmann@...il.com>,
        linux-arm-msm@...r.kernel.org, linux-i2c@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, linaro-mm-sig@...ts.linaro.org
Subject: [PATCH] i2c: qcom-geni: Fix GPI DMA buffer sync-back

Fix i2c transfers using GPI DMA mode for all message types that do not set
the I2C_M_DMA_SAFE flag (e.g. SMBus "read byte").

In this case a bounce buffer is returned by i2c_get_dma_safe_msg_buf(),
and it has to synced back to the message after the transfer is done.

Add missing assignment of dma buffer in geni_i2c_gpi().

Set xferred in i2c_put_dma_safe_msg_buf() to true in case of no error to
ensure the sync-back of this dma buffer to the message.

Signed-off-by: Robin Reckmann <robin.reckmann@...il.com>
---
 drivers/i2c/busses/i2c-qcom-geni.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-qcom-geni.c b/drivers/i2c/busses/i2c-qcom-geni.c
index 6ac402ea58fb..d3541e94794e 100644
--- a/drivers/i2c/busses/i2c-qcom-geni.c
+++ b/drivers/i2c/busses/i2c-qcom-geni.c
@@ -484,12 +484,12 @@ static void geni_i2c_gpi_unmap(struct geni_i2c_dev *gi2c, struct i2c_msg *msg,
 {
 	if (tx_buf) {
 		dma_unmap_single(gi2c->se.dev->parent, tx_addr, msg->len, DMA_TO_DEVICE);
-		i2c_put_dma_safe_msg_buf(tx_buf, msg, false);
+		i2c_put_dma_safe_msg_buf(tx_buf, msg, !gi2c->err);
 	}
 
 	if (rx_buf) {
 		dma_unmap_single(gi2c->se.dev->parent, rx_addr, msg->len, DMA_FROM_DEVICE);
-		i2c_put_dma_safe_msg_buf(rx_buf, msg, false);
+		i2c_put_dma_safe_msg_buf(rx_buf, msg, !gi2c->err);
 	}
 }
 
@@ -553,6 +553,7 @@ static int geni_i2c_gpi(struct geni_i2c_dev *gi2c, struct i2c_msg *msg,
 	desc->callback_param = gi2c;
 
 	dmaengine_submit(desc);
+	*buf = dma_buf;
 	*dma_addr_p = addr;
 
 	return 0;
-- 
2.25.1