On Oct 10, 2013 3:51 PM, "Mark Brown" <[email protected]> wrote: > > On Thu, Oct 10, 2013 at 02:44:28PM -0700, Trent Piepho wrote: > > > It looks like maybe this master can only support one bits_per_word > > value? But unlike many devices that just support 8-bits, it can > > support one of 8, 16, or 32 depending on "something", and that > > something is specified in the device tree here? No way to query the > > device? > > I have to say that (not having looked at the driver or the patch really) > I'd have hoped that this was giving a maximum not a fixed number, if the > hardware is wired to only support a single value that's anything other > than 8 bits per word most devices won't work.
>From my look at the driver, it's definitely a single fixed value. I don't know this hardware, but my guess is it's chosen when a FPGA image is designed. So the hardware itself is not strictly fixed, but Linux is stuck with whatever the IP core was configured as when the image was made. Maybe someone from Xilinx can clarify. > > > Because if you're just trying to set the default bits per word value > > it shouldn't be a property of the master, but rather a generic slave > > property like spi-max-frequency or spi-cs-high. > > It shouldn't be a property at all I'd expect, I'd expect it to be > something that's hard coded into the client driver mostly - unless the > controller really is brain dead. Probably why no one's needed the property. There is spidev, which wouldn't know what value to use, but that can be set via ioctl, which makes more sense. ------------------------------------------------------------------------------ October Webinars: Code for Performance Free Intel webinars can help you accelerate application performance. Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most from the latest Intel processors and coprocessors. See abstracts and register > http://pubads.g.doubleclick.net/gampad/clk?id=60134071&iu=/4140/ostg.clktrk _______________________________________________ spi-devel-general mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/spi-devel-general
