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Fix an error that can cause fsl espi task blocked for more than 120 seconds

Message ID 1430523462-12306-1-git-send-email-Jane.Wan@gainspeed.com (mailing list archive)
State Accepted
Commit 7a0a1759f7b157f56b8f291f3664db4b65963c8a
Headers show

Commit Message

Jane Wan May 1, 2015, 11:37 p.m. UTC
Incorrect condition is used in spin_event_timeout().  When the TX is done, the SPIE_NF bit in ESPI_SPIE register is set to 1 to indicate the Tx FIFO is not full.  If the bit is 0, it indicates the Tx FIFO is full.

Due to this error, if the Tx FIFO is full at the beginning, but becomes not full after handling the Rx FIFO (the SPIE_NF bit is set), the spin_event_timeout() returns with timeout occurred.  It causes the interrupt handler not to send completion notification to the thread that called wait_for_complete() waiting for the notification.

Signed-off-by: Jane Wan <Jane.Wan@gainspeed.com>
---
 drivers/spi/spi-fsl-espi.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

Comments

Mark Brown May 21, 2015, 9:19 p.m. UTC | #1
On Fri, May 01, 2015 at 04:37:42PM -0700, Jane Wan wrote:

> Incorrect condition is used in spin_event_timeout().  When the TX is
> done, the SPIE_NF bit in ESPI_SPIE register is set to 1 to indicate
> the Tx FIFO is not full.  If the bit is 0, it indicates the Tx FIFO is
> full.

Applied, thanks.  Please submit patches in the format covered in
SubmittingPatches - use subject lines matching the style for the
subsysetem and keep commit message lines below 80 columns.
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Patch

diff --git a/drivers/spi/spi-fsl-espi.c b/drivers/spi/spi-fsl-espi.c
index 9011e5d..333d5c2 100644
--- a/drivers/spi/spi-fsl-espi.c
+++ b/drivers/spi/spi-fsl-espi.c
@@ -551,9 +551,13 @@  void fsl_espi_cpu_irq(struct mpc8xxx_spi *mspi, u32 events)
 
 		/* spin until TX is done */
 		ret = spin_event_timeout(((events = mpc8xxx_spi_read_reg(
-				&reg_base->event)) & SPIE_NF) == 0, 1000, 0);
+				&reg_base->event)) & SPIE_NF), 1000, 0);
 		if (!ret) {
 			dev_err(mspi->dev, "tired waiting for SPIE_NF\n");
+
+			/* Clear the SPIE bits */
+			mpc8xxx_spi_write_reg(&reg_base->event, events);
+			complete(&mspi->done);
 			return;
 		}
 	}