Re: spi transfer with zero length

2008-02-17 Thread Atsushi Nemoto
On Sat, 16 Feb 2008 10:58:48 -0800, David Brownell <[EMAIL PROTECTED]> wrote: > On Saturday 16 February 2008, Atsushi Nemoto wrote: > > Hi. Is it legal to use zero for 'len' field of struct spi_transfer? > > I mean, len=0, tx_buf=rx_buf=NULL, delay_usecs!=0. > > Yes that should work ... it's unco

Re: spi transfer with zero length

2008-02-16 Thread David Brownell
On Saturday 16 February 2008, Atsushi Nemoto wrote: > Hi. Is it legal to use zero for 'len' field of struct spi_transfer? > I mean, len=0, tx_buf=rx_buf=NULL, delay_usecs!=0. Yes that should work ... it's uncommon, but not illegal. Some controller drivers may even handle that right! If the dela

spi transfer with zero length

2008-02-16 Thread Atsushi Nemoto
Hi. Is it legal to use zero for 'len' field of struct spi_transfer? I mean, len=0, tx_buf=rx_buf=NULL, delay_usecs!=0. Some SPI devices need slightly long delay before first CLK edge after CS assertion. To achieve this, I think inserting using a zero length transfer before real transfers. But i