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authorGeert Uytterhoeven <geert+renesas@glider.be>2014-04-14 17:39:53 (GMT)
committerMark Brown <broonie@linaro.org>2014-04-18 17:24:38 (GMT)
commit83596fbeb5d28e8cb8878786133945d4dc7c0090 (patch)
treeb2ae5e910185145763a5a8a2a47628551147aba8 /drivers/spi/spi.c
parentc9eaa447e77efe77b7fa4c953bd62de8297fd6c5 (diff)
downloadlinux-83596fbeb5d28e8cb8878786133945d4dc7c0090.tar.xz
spi: core: Ignore unsupported Dual/Quad Transfer Mode bits
The availability of SPI Dual or Quad Transfer Mode as indicated by the "spi-tx-bus-width" and "spi-rx-bus-width" properties in the device tree is a hardware property of the SPI master, SPI slave, and board wiring. Hence the SPI core should not reject an SPI slave because an SPI master driver doesn't (yet) support Dual or Quad Transfer Mode. Change the lack of Dual or Quad Transfer Mode support in the SPI master driver from an error condition to a warning condition, and ignore the unsupported mode bits, falling back to Single Transfer Mode, to avoid breakages when running old kernels with new device trees. Fixes: f477b7fb13df (spi: DUAL and QUAD support) Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Mark Brown <broonie@linaro.org> Cc: stable@vger.kernel.org
Diffstat (limited to 'drivers/spi/spi.c')
-rw-r--r--drivers/spi/spi.c11
1 files changed, 10 insertions, 1 deletions
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 4eb9bf0..1534fa1 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1756,7 +1756,7 @@ EXPORT_SYMBOL_GPL(spi_busnum_to_master);
*/
int spi_setup(struct spi_device *spi)
{
- unsigned bad_bits;
+ unsigned bad_bits, ugly_bits;
int status = 0;
/* check mode to prevent that DUAL and QUAD set at the same time
@@ -1776,6 +1776,15 @@ int spi_setup(struct spi_device *spi)
* that aren't supported with their current master
*/
bad_bits = spi->mode & ~spi->master->mode_bits;
+ ugly_bits = bad_bits &
+ (SPI_TX_DUAL | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD);
+ if (ugly_bits) {
+ dev_warn(&spi->dev,
+ "setup: ignoring unsupported mode bits %x\n",
+ ugly_bits);
+ spi->mode &= ~ugly_bits;
+ bad_bits &= ~ugly_bits;
+ }
if (bad_bits) {
dev_err(&spi->dev, "setup: unsupported mode bits %x\n",
bad_bits);