linux-kernel - [PATCH] spi: imx: wait_for_completion

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Message-Id: <1466511174-17048-1-git-send-email-christian.gmeiner@gmail.com>
Date:	Tue, 21 Jun 2016 14:12:54 +0200
From:	Christian Gmeiner <christian.gmeiner@...il.com>
To:	linux-spi@...r.kernel.org
Cc:	broonie@...nel.org, linux-kernel@...r.kernel.org,
	Christian Gmeiner <christian.gmeiner@...il.com>
Subject: [PATCH] spi: imx: wait_for_completion_timeout(..) for PIO transfers

In some rare cases I see the following 'task blocked' information. It
looks like the PIO transfer has some problems and never succeeds. Make
use of wait_for_completion_timeout(..) to detect this case and
return -ETIMEDOUT.

[ 240.246067] INFO: task hexdump:1660 blocked for more than 120 seconds.
[ 240.246089] Not tainted 4.1.17 0000001
[ 240.246099] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 240.246109] hexdump D c0575548 0 1660 1 0x00000000
[ 240.246132] Backtrace:
[ 240.246166] [<c057524c>] (__schedule) from [<c0575a84>] (schedule+0x40/0xa4)
[ 240.246176] r10:00000000 r9:c07f1300 r8:c07b8408 r7:c0576518 r6:7fffffff r5:7fffffff
[ 240.246210] r4:ee972e7c
[ 240.246233] [<c0575a44>] (schedule) from [<c0578544>] (schedule_timeout+0x174/0x274)
[ 240.246254] [<c05783d0>] (schedule_timeout) from [<c0576518>] (wait_for_common+0xc0/0x164)
[ 240.246263] r10:00000000 r9:c07f1300 r8:00000002 r7:00000000 r6:7fffffff r5:ee972e78
[ 240.246294] r4:ee972e7c
[ 240.246314] [<c0576458>] (wait_for_common) from [<c05765dc>] (wait_for_completion+0x20/0x24)
[ 240.246324] r10:ee972e50 r8:00000001 r7:c3976200 r6:ee972c00 r5:ee972e50 r4:c2c87d28
[ 240.246367] [<c05765bc>] (wait_for_completion) from [<c03f6b04>] (spi_imx_transfer+0xe8/0x3cc)
[ 240.246393] [<c03f6a1c>] (spi_imx_transfer) from [<c03f50e4>] (spi_bitbang_transfer_one+0xb4/0x250)
[ 240.246403] r10:ee972e50 r8:00000001 r7:00000000 r6:c2c87da0 r5:00000000 r4:c2c87d28
[ 240.246443] [<c03f5030>] (spi_bitbang_transfer_one) from [<c03f36e8>] (__spi_pump_messages+0x36c/0x6b4)
[ 240.246452] r10:ee9e5010 r9:00000001 r8:ee9e5010 r7:00000000 r6:c2c87da0 r5:c2c87d6c
[ 240.246483] r4:ee972c00
[ 240.246503] [<c03f337c>] (__spi_pump_messages) from [<c03f3b68>] (__spi_sync+0x138/0x1e4)
[ 240.246512] r10:00000000 r9:00000000 r8:c03f25a8 r7:00000000 r6:ee972c00 r5:c3976200
[ 240.246542] r4:c2c87da0
[ 240.246562] [<c03f3a30>] (__spi_sync) from [<c03f3c50>] (spi_sync+0x1c/0x20)
[ 240.246571] r10:00040000 r9:00000000 r8:c3976200 r7:00000000 r6:ee973300 r5:c2c87da0
[ 240.246602] r4:ee973014
[ 240.246623] [<c03f3c34>] (spi_sync) from [<c03f0210>] (m25p80_read+0xf8/0x124)
[ 240.246641] [<c03f0118>] (m25p80_read) from [<c03f1528>] (spi_nor_read+0x64/0x80)
[ 240.246651] r10:00004000 r8:00004000 r7:00000000 r6:00040000 r5:00000000 r4:ee973014
[ 240.246698] [<c03f14c4>] (spi_nor_read) from [<c03cdcb4>] (mtd_read+0x98/0xcc)
[ 240.246708] r7:c2c87ea0 r6:ee973098 r5:00000000 r4:001c0000
[ 240.246740] [<c03cdc1c>] (mtd_read) from [<c03d300c>] (mtdchar_read+0xcc/0x204)
[ 240.246750] r9:ed424000 r8:00000000 r7:b495d018 r6:c2c87f78 r5:00000000 r4:00040000
[ 240.246793] [<c03d2f40>] (mtdchar_read) from [<c013b1c4>] (__vfs_read+0x3c/0xe0)
[ 240.246803] r10:00004000 r9:00000000 r8:c2c87f78 r7:b495d018 r6:c2c87f78 r5:c05c8104
[ 240.246833] r4:c32fe600
[ 240.246852] [<c013b188>] (__vfs_read) from [<c013befc>] (vfs_read+0x98/0x154)
[ 240.246861] r10:00000000 r8:00040000 r7:00004000 r6:c2c87f78 r5:b495d018 r4:c32fe600
[ 240.246899] [<c013be64>] (vfs_read) from [<c013c008>] (SyS_read+0x50/0x90)
[ 240.246908] r10:00000000 r8:00040000 r7:b495d018 r6:00004000 r5:c32fe601 r4:c32fe600
[ 240.246953] [<c013bfb8>] (SyS_read) from [<c000fa60>] (ret_fast_syscall+0x0/0x3c)
[ 240.246962] r9:c2c86000 r8:c000fc04 r7:00000003 r6:00004000 r5:00000000 r4:b495d018

Signed-off-by: Christian Gmeiner <christian.gmeiner@...il.com>
---
 drivers/spi/spi-imx.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
index 50769078..d2b96b1 100644
--- a/drivers/spi/spi-imx.c
+++ b/drivers/spi/spi-imx.c
@@ -1050,6 +1050,8 @@ static int spi_imx_pio_transfer(struct spi_device *spi,
 				struct spi_transfer *transfer)
 {
 	struct spi_imx_data *spi_imx = spi_master_get_devdata(spi->master);
+	unsigned long transfer_timeout;
+	unsigned long timeout;
 
 	spi_imx->tx_buf = transfer->tx_buf;
 	spi_imx->rx_buf = transfer->rx_buf;
@@ -1062,7 +1064,15 @@ static int spi_imx_pio_transfer(struct spi_device *spi,
 
 	spi_imx->devtype_data->intctrl(spi_imx, MXC_INT_TE);
 
-	wait_for_completion(&spi_imx->xfer_done);
+	transfer_timeout = spi_imx_calculate_timeout(spi_imx, transfer->len);
+
+	timeout = wait_for_completion_timeout(&spi_imx->xfer_done,
+					      transfer_timeout);
+	if (!timeout) {
+		dev_err(&spi->dev, "I/O Error in PIO\n");
+		spi_imx->devtype_data->reset(spi_imx);
+		return -ETIMEDOUT;
+	}
 
 	return transfer->len;
 }
-- 
2.5.5