2015-12-17 09:29:22 +00:00
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From 3604c2a5b623829c9127d312813f3427531ebfcd Mon Sep 17 00:00:00 2001
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2015-10-26 09:01:05 +00:00
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From: Martin Sperl <kernel@martin.sperl.org>
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Date: Wed, 29 Jul 2015 07:34:10 +0000
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2015-12-17 09:29:22 +00:00
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Subject: [PATCH 176/222] spi: bcm2835: fix overflow in calculation of transfer
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2015-10-26 09:01:05 +00:00
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time
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This resulted in the use of polling mode when other approaches
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(dma or interrupts) would have been more appropriate.
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Happened for transfers longer than 477 bytes.
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Reported-by: Noralf Tronnes <noralf@tronnes.org>
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Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
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Signed-off-by: Mark Brown <broonie@kernel.org>
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(cherry picked from commit 0122a5183088e3117bb9c8fbe248914efb502f3f)
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---
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drivers/spi/spi-bcm2835.c | 10 ++++++----
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1 file changed, 6 insertions(+), 4 deletions(-)
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--- a/drivers/spi/spi-bcm2835.c
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+++ b/drivers/spi/spi-bcm2835.c
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@@ -480,7 +480,7 @@ static int bcm2835_spi_transfer_one_poll
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struct spi_device *spi,
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struct spi_transfer *tfr,
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u32 cs,
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- unsigned long xfer_time_us)
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+ unsigned long long xfer_time_us)
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{
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struct bcm2835_spi *bs = spi_master_get_devdata(master);
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unsigned long timeout;
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@@ -531,7 +531,8 @@ static int bcm2835_spi_transfer_one(stru
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{
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struct bcm2835_spi *bs = spi_master_get_devdata(master);
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unsigned long spi_hz, clk_hz, cdiv;
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- unsigned long spi_used_hz, xfer_time_us;
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+ unsigned long spi_used_hz;
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+ unsigned long long xfer_time_us;
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u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS);
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/* set clock */
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@@ -573,9 +574,10 @@ static int bcm2835_spi_transfer_one(stru
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bs->rx_len = tfr->len;
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/* calculate the estimated time in us the transfer runs */
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- xfer_time_us = tfr->len
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+ xfer_time_us = (unsigned long long)tfr->len
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* 9 /* clocks/byte - SPI-HW waits 1 clock after each byte */
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- * 1000000 / spi_used_hz;
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+ * 1000000;
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+ do_div(xfer_time_us, spi_used_hz);
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/* for short requests run polling*/
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if (xfer_time_us <= BCM2835_SPI_POLLING_LIMIT_US)
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