[linux-yocto] [PATCH 06/14] spi: bcm2835: fix overflow in calculation of transfer time
Weifeng Voon
weifeng.voon at intel.com
Thu Jun 16 01:25:43 PDT 2016
From: Martin Sperl <kernel at martin.sperl.org>
This resulted in the use of polling mode when other approaches
(dma or interrupts) would have been more appropriate.
Happened for transfers longer than 477 bytes.
Reported-by: Noralf Tronnes <noralf at tronnes.org>
Signed-off-by: Martin Sperl <kernel at martin.sperl.org>
Signed-off-by: Mark Brown <broonie at kernel.org>
(cherry picked from commit 0122a5183088e3117bb9c8fbe248914efb502f3f)
Signed-off-by: Weifeng Voon <weifeng.voon at intel.com>
---
drivers/spi/spi-bcm2835.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c
index c9357bb..e7874a6 100644
--- a/drivers/spi/spi-bcm2835.c
+++ b/drivers/spi/spi-bcm2835.c
@@ -480,7 +480,7 @@ static int bcm2835_spi_transfer_one_poll(struct spi_master *master,
struct spi_device *spi,
struct spi_transfer *tfr,
u32 cs,
- unsigned long xfer_time_us)
+ unsigned long long xfer_time_us)
{
struct bcm2835_spi *bs = spi_master_get_devdata(master);
unsigned long timeout;
@@ -531,7 +531,8 @@ static int bcm2835_spi_transfer_one(struct spi_master *master,
{
struct bcm2835_spi *bs = spi_master_get_devdata(master);
unsigned long spi_hz, clk_hz, cdiv;
- unsigned long spi_used_hz, xfer_time_us;
+ unsigned long spi_used_hz;
+ unsigned long long xfer_time_us;
u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS);
/* set clock */
@@ -573,9 +574,10 @@ static int bcm2835_spi_transfer_one(struct spi_master *master,
bs->rx_len = tfr->len;
/* calculate the estimated time in us the transfer runs */
- xfer_time_us = tfr->len
+ xfer_time_us = (unsigned long long)tfr->len
* 9 /* clocks/byte - SPI-HW waits 1 clock after each byte */
- * 1000000 / spi_used_hz;
+ * 1000000;
+ do_div(xfer_time_us, spi_used_hz);
/* for short requests run polling*/
if (xfer_time_us <= BCM2835_SPI_POLLING_LIMIT_US)
--
1.9.1
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