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spi/bitbang: add support for SPI_MASTER_NO_{TX, RX} modes

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This patch adds a new flags argument to bitbang_txrx_be_cpha0 and
bitbang_txrx_be_cpha1 transfer functions. This enables support for
SPI_MASTER_NO_{TX,RX} transfer modes. The change should have no impact
on speed of the existing drivers. bitbank_txrx_* functions are usually
inlined into the drivers. When the argument is equal to constant zero,
the optimizer would be able to eliminate the dead code (flags checks)
easily. Tested on ARM and GCC 4.4.x and in all cases the checks were
eliminated in the inlined function.

Reviewed-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
This commit is contained in:
Marek Szyprowski
2010-06-30 14:27:32 -06:00
committed by Grant Likely
parent 5c2818cdfa
commit 04bb2a031c
6 changed files with 24 additions and 20 deletions
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2
drivers/spi/spi_butterfly.c
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@@ -156,7 +156,7 @@ butterfly_txrx_word_mode0(struct spi_device *spi,
unsigned nsecs,
u32 word, u8 bits)
{
return bitbang_txrx_be_cpha0(spi, nsecs, 0, word, bits);
return bitbang_txrx_be_cpha0(spi, nsecs, 0, 0, word, bits);
}
/*----------------------------------------------------------------------*/