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From 6e1447aaad894f45595a45fc52ae5f7dbe072b2e Mon Sep 17 00:00:00 2001
From: Martin Sperl <kernel@martin.sperl.org>
Date: Wed, 29 Jul 2015 07:34:10 +0000
Subject: [PATCH 176/203] 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>
(cherry picked from commit 0122a5183088e3117bb9c8fbe248914efb502f3f)
---
drivers/spi/spi-bcm2835.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
--- 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_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(stru
{
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(stru
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)
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