spi/omap_mcspi: catch xfers of non-multiple SPI word size

If an SPI access was not a multiple of the SPI word size,
the while() loop would spin and the rx/tx ptrs would be incremented
indefinitely.

Signed-off-by: Michael Jones <michael.jones@matrix-vision.de>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

1 files changed, 6 insertions, 3 deletions

diff --git a/drivers/spi/omap2_mcspi.c b/drivers/spi/omap2_mcspi.c
index 1a2d0b8bdd6a..6a982a25b7c3 100644
--- a/drivers/spi/omap2_mcspi.c
+++ b/drivers/spi/omap2_mcspi.c
@@ -487,6 +487,9 @@ omap2_mcspi_txrx_pio(struct spi_device *spi, struct spi_transfer *xfer)
         rx_reg          = base + OMAP2_MCSPI_RX0;
         chstat_reg      = base + OMAP2_MCSPI_CHSTAT0;
 
+        if (c < (word_len>>3))
+                return 0;
+
         if (word_len <= 8) {
                 u8              *rx;
                 const u8        *tx;
@@ -534,7 +537,7 @@ 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);
+                } while (c > (word_len>>3));
         } else if (word_len <= 16) {
                 u16             *rx;
                 const u16       *tx;
@@ -581,7 +584,7 @@ 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);
+                } while (c > (word_len>>3));
         } else if (word_len <= 32) {
                 u32             *rx;
                 const u32       *tx;
@@ -628,7 +631,7 @@ 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);
+                } while (c > (word_len>>3));
         }
 
         /* for TX_ONLY mode, be sure all words have shifted out */