On Mon, Mar 21, 2011 at 7:57 PM, Jarkko Nikula <jhnikula@xxxxxxxxx> wrote:
> Commit adef658 "spi/omap_mcspi: catch xfers of non-multiple SPI word size"
> broke the transmission of last word in cases where access is multiple of
> word size and word size is 16 or 32 bits.
>
> Fix this by replacing the test "c > (word_len>>3)" in do-while loops with
> "c >= 'pointer increment size'". This ensures that the last word is
> transmitted in above case and still allow to break the loop and prevent
> variable c underflow in cases where word size != 'pointer increment size'.
>
> Signed-off-by: Jarkko Nikula <jhnikula@xxxxxxxxx>
> Cc: Michael Jones <michael.jones@xxxxxxxxxxxxxxxx>
> ---
> I noticed the issue with wl1251 WLAN driver on Nokia N900 using today's
> vanilla head a44f99c7efdb88fa41128065c9a9445c19894e34.
> ---
> drivers/spi/omap2_mcspi.c | 6 +++---
> 1 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/spi/omap2_mcspi.c b/drivers/spi/omap2_mcspi.c
> index 3a5ed06..6f86ba0 100644
> --- a/drivers/spi/omap2_mcspi.c
> +++ b/drivers/spi/omap2_mcspi.c
> @@ -517,7 +517,7 @@ omap2_mcspi_txrx_pio(struct spi_device *spi, struct spi_transfer *xfer)
> dev_vdbg(&spi->dev, "read-%d %02x\n",
> word_len, *(rx - 1));
> }
> - } while (c > (word_len>>3));
> + } while (c);
> } else if (word_len <= 16) {
> u16 *rx;
> const u16 *tx;
> @@ -564,7 +564,7 @@ omap2_mcspi_txrx_pio(struct spi_device *spi, struct spi_transfer *xfer)
> dev_vdbg(&spi->dev, "read-%d %04x\n",
> word_len, *(rx - 1));
> }
> - } while (c > (word_len>>3));
> + } while (c >= 2);
> } else if (word_len <= 32) {
> u32 *rx;
> const u32 *tx;
> @@ -611,7 +611,7 @@ omap2_mcspi_txrx_pio(struct spi_device *spi, struct spi_transfer *xfer)
> dev_vdbg(&spi->dev, "read-%d %08x\n",
> word_len, *(rx - 1));
> }
> - } while (c > (word_len>>3));
> + } while (c >= 4);
> }
>
> /* for TX_ONLY mode, be sure all words have shifted out */
> --
> 1.7.4.1
Latest mainline when booted on Omap4 was not booting up.
It crashes showing something like this:
[ 2.581634] ks8851 spi1.0: (unregistered net_device): spi_sync() failed
[ 2.589843] ks8851 spi1.0: (unregistered net_device): spi_sync() failed
[ 2.597900] ks8851 spi1.0: (unregistered net_device): read: spi_sync() failed
[ 2.605499] ks8851 spi1.0: failed to read device ID
The above patch when applied to the mainline solves the problem and the
kernel boots fine on Omap4.
Tested-by: Sourav Poddar<sourav.poddar@xxxxxx>
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