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Subject[PATCH 07/11] spi: Deal with slaves that return from transfer_one() unfinished
Date
Some drivers, such as spi-pxa2xx return from the transfer_one callback
immediately, idicating that the transfer will be finished asynchronously.

Normally, spi_transfer_one_message() synchronously waits for the
transfer to finish with wait_for_completion_timeout(). For slaves, we
don't want the transaction to time out as it can complete in a long time
in future. Use wait_for_completion_interruptible() instead.

Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
---
drivers/spi/spi.c | 64 +++++++++++++++++++++++++++++++----------------
1 file changed, 42 insertions(+), 22 deletions(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 9da0bc5a036c..079214a31d2c 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -993,6 +993,44 @@ static int spi_map_msg(struct spi_controller *ctlr, struct spi_message *msg)
return __spi_map_msg(ctlr, msg);
}

+static int spi_transfer_wait(struct spi_controller *ctlr,
+ struct spi_message *msg,
+ struct spi_transfer *xfer)
+{
+ struct spi_statistics *statm = &ctlr->statistics;
+ struct spi_statistics *stats = &msg->spi->statistics;
+ unsigned long long ms = 1;
+
+ if (spi_controller_is_slave(ctlr)) {
+ if (wait_for_completion_interruptible(&ctlr->xfer_completion)) {
+ dev_dbg(&msg->spi->dev, "SPI transfer interrupted\n");
+ return -EINTR;
+ }
+ } else {
+ ms = 8LL * 1000LL * xfer->len;
+ do_div(ms, xfer->speed_hz);
+ ms += ms + 200; /* some tolerance */
+
+ if (ms > UINT_MAX)
+ ms = UINT_MAX;
+
+ ms = wait_for_completion_timeout(&ctlr->xfer_completion,
+ msecs_to_jiffies(ms));
+
+ if (ms == 0) {
+ SPI_STATISTICS_INCREMENT_FIELD(statm,
+ timedout);
+ SPI_STATISTICS_INCREMENT_FIELD(stats,
+ timedout);
+ dev_err(&msg->spi->dev,
+ "SPI transfer timed out\n");
+ msg->status = -ETIMEDOUT;
+ }
+ }
+
+ return 0;
+}
+
/*
* spi_transfer_one_message - Default implementation of transfer_one_message()
*
@@ -1006,7 +1044,6 @@ static int spi_transfer_one_message(struct spi_controller *ctlr,
struct spi_transfer *xfer;
bool keep_cs = false;
int ret = 0;
- unsigned long long ms = 1;
struct spi_statistics *statm = &ctlr->statistics;
struct spi_statistics *stats = &msg->spi->statistics;

@@ -1035,28 +1072,11 @@ static int spi_transfer_one_message(struct spi_controller *ctlr,
goto out;
}

- if (ret > 0) {
- ret = 0;
- ms = 8LL * 1000LL * xfer->len;
- do_div(ms, xfer->speed_hz);
- ms += ms + 200; /* some tolerance */
-
- if (ms > UINT_MAX)
- ms = UINT_MAX;
+ if (ret > 0)
+ ret = spi_transfer_wait(ctlr, msg, xfer);

- ms = wait_for_completion_timeout(&ctlr->xfer_completion,
- msecs_to_jiffies(ms));
- }
-
- if (ms == 0) {
- SPI_STATISTICS_INCREMENT_FIELD(statm,
- timedout);
- SPI_STATISTICS_INCREMENT_FIELD(stats,
- timedout);
- dev_err(&msg->spi->dev,
- "SPI transfer timed out\n");
- msg->status = -ETIMEDOUT;
- }
+ if (ret < 0)
+ return ret;
} else {
if (xfer->len)
dev_err(&msg->spi->dev,
--
2.19.0
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