[PATCH] i2c: stm32f7: Move reinit_completion() to stm32f7_i2c_xfer_core()

[Marek Vasut]

Currently, the driver may repeatedly call reinit_completion() during
transfer which contains multiple messages, while another thread is
waiting for the completion.

This happens during transfer with more than 1 message, invoked via
stm32f7_i2c_xfer_core() -> stm32f7_i2c_xfer_msg(). After invoking the
stm32f7_i2c_xfer_msg() to start transfer, stm32f7_i2c_xfer_core()
calls wait_for_completion_timeout() to wait for completion of the
transfer of all messages. When the first message transfer completes,
the hard IRQ handler triggers, and detects transfer completion, which
leads to stm32f7_i2c_isr_event_thread() IRQ thread being started. The
stm32f7_i2c_isr_event_thread() calls stm32f7_i2c_xfer_msg() in case
there are more messages.

Without this change, the second and later stm32f7_i2c_xfer_msg() would
call reinit_completion() on the completion which is still being waited
for in stm32f7_i2c_xfer_core(). Fix this by moving the reinit_completion()
into stm32f7_i2c_xfer_core(), together with wait_for_completion_timeout().

Since stm32f7_i2c_xfer_core() now waits for completion of the entire
transfer, increase the default timeout. This fixes sporadic transfer
timeouts on STM32MP25xx during kernel boot.

Fixes: aeb068c57214 ("i2c: i2c-stm32f7: add driver")
Signed-off-by: Marek Vasut <marex at nabladev.com>
---
Cc: Alain Volmat <alain.volmat at foss.st.com>
Cc: Alexandre Torgue <alexandre.torgue at foss.st.com>
Cc: Andi Shyti <andi.shyti at kernel.org>
Cc: Maxime Coquelin <mcoquelin.stm32 at gmail.com>
Cc: Pierre-Yves MORDRET <pierre-yves.mordret at foss.st.com>
Cc: linux-arm-kernel at lists.infradead.org
Cc: linux-i2c at vger.kernel.org
Cc: linux-kernel at vger.kernel.org
Cc: linux-stm32 at st-md-mailman.stormreply.com
---
 drivers/i2c/busses/i2c-stm32f7.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
index 70cb5822bf17b..53d9df70ebe4d 100644
--- a/drivers/i2c/busses/i2c-stm32f7.c
+++ b/drivers/i2c/busses/i2c-stm32f7.c
@@ -895,8 +895,6 @@ static void stm32f7_i2c_xfer_msg(struct stm32f7_i2c_dev *i2c_dev,
 	f7_msg->result = 0;
 	f7_msg->stop = (i2c_dev->msg_id >= i2c_dev->msg_num - 1);
 
-	reinit_completion(&i2c_dev->complete);
-
 	cr1 = readl_relaxed(base + STM32F7_I2C_CR1);
 	cr2 = readl_relaxed(base + STM32F7_I2C_CR2);
 
@@ -1728,6 +1726,8 @@ static int stm32f7_i2c_xfer_core(struct i2c_adapter *i2c_adap,
 	if (ret)
 		goto pm_free;
 
+	reinit_completion(&i2c_dev->complete);
+
 	stm32f7_i2c_xfer_msg(i2c_dev, msgs);
 
 	if (!i2c_dev->atomic)
@@ -2253,7 +2253,7 @@ static int stm32f7_i2c_probe(struct platform_device *pdev)
 	snprintf(adap->name, sizeof(adap->name), "STM32F7 I2C(%pa)",
 		 &res->start);
 	adap->owner = THIS_MODULE;
-	adap->timeout = 2 * HZ;
+	adap->timeout = 8 * HZ;
 	adap->retries = 3;
 	adap->algo = &stm32f7_i2c_algo;
 	adap->dev.parent = &pdev->dev;
-- 
2.53.0