target/linux/brcm2708/patches-4.1/0182-backport-spi-bcm2835-BUG-fix-wrong-use-of-PAGE_MASK.patch

   1 From 6460bf849143979acff90f3664f78bf3907aad0f Mon Sep 17 00:00:00 2001
   2 From: Martin Sperl <kernel@martin.sperl.org>
   3 Date: Thu, 10 Sep 2015 09:32:14 +0000
   4 Subject: [PATCH 182/203] backport: spi: bcm2835: BUG: fix wrong use of
   5  PAGE_MASK
   6
   7 There is a bug in the alignment checking of transfers,
   8 that results in DMA not being used for un-aligned
   9 transfers that do not cross page-boundries, which is valid.
  10
  11 This is due to a missconception of the meaning PAGE_MASK
  12 when implementing that check originally - (PAGE_SIZE - 1)
  13 should have been used instead.
  14
  15 Also fixes a copy/paste error.
  16
  17 Reported-by: <robert@axium.co.nz>
  18 Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
  19 Signed-off-by: Mark Brown <broonie@kernel.org>
  20 Cc: stable@vger.kernel.org
  21 ---
  22  drivers/spi/spi-bcm2835.c | 6 +++---
  23  1 file changed, 3 insertions(+), 3 deletions(-)
  24
  25 --- a/drivers/spi/spi-bcm2835.c
  26 +++ b/drivers/spi/spi-bcm2835.c
  27 @@ -386,14 +386,14 @@ static bool bcm2835_spi_can_dma(struct s
  28         /* otherwise we only allow transfers within the same page
  29          * to avoid wasting time on dma_mapping when it is not practical
  30          */
  31 -       if (((size_t)tfr->tx_buf & PAGE_MASK) + tfr->len > PAGE_SIZE) {
  32 +       if (((size_t)tfr->tx_buf & (PAGE_SIZE - 1)) + tfr->len > PAGE_SIZE) {
  33                 dev_warn_once(&spi->dev,
  34                               "Unaligned spi tx-transfer bridging page\n");
  35                 return false;
  36         }
  37 -       if (((size_t)tfr->rx_buf & PAGE_MASK) + tfr->len > PAGE_SIZE) {
  38 +       if (((size_t)tfr->rx_buf & (PAGE_SIZE - 1)) + tfr->len > PAGE_SIZE) {
  39                 dev_warn_once(&spi->dev,
  40 -                             "Unaligned spi tx-transfer bridging page\n");
  41 +                             "Unaligned spi rx-transfer bridging page\n");
  42                 return false;
  43         }
  44