spi: bcm2835: fix overflow in calculation of transfer time
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@tronnes.org>
Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
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 @@
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 @@
{
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 @@
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)