linux-kernel - [PATCH 3.16 186/305] spi: sunxi: fix transfer timeout

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Message-ID: <lsq.1471110171.451603204@decadent.org.uk>
Date:	Sat, 13 Aug 2016 18:42:51 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org, "Mark Brown" <broonie@...nel.org>,
	"Maxime Ripard" <maxime.ripard@...e-electrons.com>,
	"Michal Suchanek" <hramrach@...il.com>
Subject: [PATCH 3.16 186/305] spi: sunxi: fix transfer timeout

3.16.37-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Michal Suchanek <hramrach@...il.com>

commit 719bd6542044efd9b338a53dba1bef45f40ca169 upstream.

The trasfer timeout is fixed at 1000 ms. Reading a 4Mbyte flash over
1MHz SPI bus takes way longer than that. Calculate the timeout from the
actual time the transfer is supposed to take and multiply by 2 for good
measure.

Signed-off-by: Michal Suchanek <hramrach@...il.com>
Acked-by: Maxime Ripard <maxime.ripard@...e-electrons.com>
Signed-off-by: Mark Brown <broonie@...nel.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/spi/spi-sun4i.c | 10 +++++++++-
 drivers/spi/spi-sun6i.c | 10 +++++++++-
 2 files changed, 18 insertions(+), 2 deletions(-)

--- a/drivers/spi/spi-sun4i.c
+++ b/drivers/spi/spi-sun4i.c
@@ -170,6 +170,7 @@ static int sun4i_spi_transfer_one(struct
 {
 	struct sun4i_spi *sspi = spi_master_get_devdata(master);
 	unsigned int mclk_rate, div, timeout;
+	unsigned int start, end, tx_time;
 	unsigned int tx_len = 0;
 	int ret = 0;
 	u32 reg;
@@ -286,9 +287,16 @@ static int sun4i_spi_transfer_one(struct
 	reg = sun4i_spi_read(sspi, SUN4I_CTL_REG);
 	sun4i_spi_write(sspi, SUN4I_CTL_REG, reg | SUN4I_CTL_XCH);
 
+	tx_time = max(tfr->len * 8 * 2 / (tfr->speed_hz / 1000), 100U);
+	start = jiffies;
 	timeout = wait_for_completion_timeout(&sspi->done,
-					      msecs_to_jiffies(1000));
+					      msecs_to_jiffies(tx_time));
+	end = jiffies;
 	if (!timeout) {
+		dev_warn(&master->dev,
+			 "%s: timeout transferring %u bytes@...z for %i(%i)ms",
+			 dev_name(&spi->dev), tfr->len, tfr->speed_hz,
+			 jiffies_to_msecs(end - start), tx_time);
 		ret = -ETIMEDOUT;
 		goto out;
 	}
--- a/drivers/spi/spi-sun6i.c
+++ b/drivers/spi/spi-sun6i.c
@@ -160,6 +160,7 @@ static int sun6i_spi_transfer_one(struct
 {
 	struct sun6i_spi *sspi = spi_master_get_devdata(master);
 	unsigned int mclk_rate, div, timeout;
+	unsigned int start, end, tx_time;
 	unsigned int tx_len = 0;
 	int ret = 0;
 	u32 reg;
@@ -269,9 +270,16 @@ static int sun6i_spi_transfer_one(struct
 	reg = sun6i_spi_read(sspi, SUN6I_TFR_CTL_REG);
 	sun6i_spi_write(sspi, SUN6I_TFR_CTL_REG, reg | SUN6I_TFR_CTL_XCH);
 
+	tx_time = max(tfr->len * 8 * 2 / (tfr->speed_hz / 1000), 100U);
+	start = jiffies;
 	timeout = wait_for_completion_timeout(&sspi->done,
-					      msecs_to_jiffies(1000));
+					      msecs_to_jiffies(tx_time));
+	end = jiffies;
 	if (!timeout) {
+		dev_warn(&master->dev,
+			 "%s: timeout transferring %u bytes@...z for %i(%i)ms",
+			 dev_name(&spi->dev), tfr->len, tfr->speed_hz,
+			 jiffies_to_msecs(end - start), tx_time);
 		ret = -ETIMEDOUT;
 		goto out;
 	}