target/linux/brcm2708/patches-4.1/0176-spi-bcm2835-fix-overflow-in-calculation-of-transfer-.patch

   1 From 3604c2a5b623829c9127d312813f3427531ebfcd Mon Sep 17 00:00:00 2001
   2 From: Martin Sperl <kernel@martin.sperl.org>
   3 Date: Wed, 29 Jul 2015 07:34:10 +0000
   4 Subject: [PATCH 176/222] spi: bcm2835: fix overflow in calculation of transfer
   5  time
   6
   7 This resulted in the use of polling mode when other approaches
   8 (dma or interrupts) would have been more appropriate.
   9
  10 Happened for transfers longer than 477 bytes.
  11
  12 Reported-by: Noralf Tronnes <noralf@tronnes.org>
  13 Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
  14 Signed-off-by: Mark Brown <broonie@kernel.org>
  15 (cherry picked from commit 0122a5183088e3117bb9c8fbe248914efb502f3f)
  16 ---
  17  drivers/spi/spi-bcm2835.c | 10 ++++++----
  18  1 file changed, 6 insertions(+), 4 deletions(-)
  19
  20 --- a/drivers/spi/spi-bcm2835.c
  21 +++ b/drivers/spi/spi-bcm2835.c
  22 @@ -480,7 +480,7 @@ static int bcm2835_spi_transfer_one_poll
  23                                          struct spi_device *spi,
  24                                          struct spi_transfer *tfr,
  25                                          u32 cs,
  26 -                                        unsigned long xfer_time_us)
  27 +                                        unsigned long long xfer_time_us)
  28  {
  29         struct bcm2835_spi *bs = spi_master_get_devdata(master);
  30         unsigned long timeout;
  31 @@ -531,7 +531,8 @@ static int bcm2835_spi_transfer_one(stru
  32  {
  33         struct bcm2835_spi *bs = spi_master_get_devdata(master);
  34         unsigned long spi_hz, clk_hz, cdiv;
  35 -       unsigned long spi_used_hz, xfer_time_us;
  36 +       unsigned long spi_used_hz;
  37 +       unsigned long long xfer_time_us;
  38         u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS);
  39
  40         /* set clock */
  41 @@ -573,9 +574,10 @@ static int bcm2835_spi_transfer_one(stru
  42         bs->rx_len = tfr->len;
  43
  44         /* calculate the estimated time in us the transfer runs */
  45 -       xfer_time_us = tfr->len
  46 +       xfer_time_us = (unsigned long long)tfr->len
  47                 * 9 /* clocks/byte - SPI-HW waits 1 clock after each byte */
  48 -               * 1000000 / spi_used_hz;
  49 +               * 1000000;
  50 +       do_div(xfer_time_us, spi_used_hz);
  51
  52         /* for short requests run polling*/
  53         if (xfer_time_us <= BCM2835_SPI_POLLING_LIMIT_US)