This reverts commit 232a5adc5199 ("spi: bitbang: only toggle
bitchanges") because it breaks bitbanged SPI on our MIPS system. I
found two problems with the patch:
- oldbit must initially be computed from bit position 7, 15 or 31 of
word depending on the value of bits.
- The optimization also does not eliminate consecutive ones because
the compare of 1<<31 and 1 will be false (a bool only takes values 0
or 1).
Signed-off-by: Lars Persson <[email protected]>
---
drivers/spi/spi-bitbang-txrx.h | 18 ++++--------------
1 file changed, 4 insertions(+), 14 deletions(-)
diff --git a/drivers/spi/spi-bitbang-txrx.h b/drivers/spi/spi-bitbang-txrx.h
index 06b34e5..c616e41 100644
--- a/drivers/spi/spi-bitbang-txrx.h
+++ b/drivers/spi/spi-bitbang-txrx.h
@@ -49,17 +49,12 @@ bitbang_txrx_be_cpha0(struct spi_device *spi,
{
/* if (cpol == 0) this is SPI_MODE_0; else this is SPI_MODE_2 */
- bool oldbit = !(word & 1);
/* clock starts at inactive polarity */
for (word <<= (32 - bits); likely(bits); bits--) {
/* setup MSB (to slave) on trailing edge */
- if ((flags & SPI_MASTER_NO_TX) == 0) {
- if ((word & (1 << 31)) != oldbit) {
- setmosi(spi, word & (1 << 31));
- oldbit = word & (1 << 31);
- }
- }
+ if ((flags & SPI_MASTER_NO_TX) == 0)
+ setmosi(spi, word & (1 << 31));
spidelay(nsecs); /* T(setup) */
setsck(spi, !cpol);
@@ -81,18 +76,13 @@ bitbang_txrx_be_cpha1(struct spi_device *spi,
{
/* if (cpol == 0) this is SPI_MODE_1; else this is SPI_MODE_3 */
- bool oldbit = !(word & (1 << 31));
/* clock starts at inactive polarity */
for (word <<= (32 - bits); likely(bits); bits--) {
/* setup MSB (to slave) on leading edge */
setsck(spi, !cpol);
- if ((flags & SPI_MASTER_NO_TX) == 0) {
- if ((word & (1 << 31)) != oldbit) {
- setmosi(spi, word & (1 << 31));
- oldbit = word & (1 << 31);
- }
- }
+ if ((flags & SPI_MASTER_NO_TX) == 0)
+ setmosi(spi, word & (1 << 31));
spidelay(nsecs); /* T(setup) */
setsck(spi, cpol);
--
2.1.4
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