Em Sáb, 2008-11-22 às 20:59 -0800, David Brownell escreveu: > > I tried spi_write_then_read before, but it didn't work. I supposed it > > was because it was doing 2 transfers as the second transfer rx_buf > > always came zeroed. > > You may have been using it wrong. Also, verify against > current kernels ... there have been bugfixes to pxa2xx_spi. > > > I see that commit > > f9b90e39cbc5c4d6ef60022fd1f25d541df0aad1 changed it to do a single > > transfer, so i will try it again. > > Unless it needs the full duplex capability of SPI, then > you should be able to make write_then_read work ... on > the other hand, if you do need full duplex, then you > should address the DMA. (And byteswapping, either way.)
Well, i guess it is full duplex, as i set spi_transfer.len to 4 bytes, write 4 bytes _and_ read 4 bytes to/from the chip. I'm looking at write_then_read and if I read it correctly, it sends n_tx bytes of data plus n_rx bytes of nothing, and discards n_tx bytes from the start of the receive buffer considering only n_rx bytes from the end of the receive buffer. This is not what i want. Can you be more descriptive on "address the DMA"? Im not familiar on what is the issue here. I will take care of byte swapping for the next patch. -- Daniel Ribeiro ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ spi-devel-general mailing list spi-devel-general@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/spi-devel-general
