On Thu, Oct 10, 2013 at 7:50 AM, Jens Renner <[email protected]> wrote: > Am 10.10.2013 16:12, schrieb Mark Brown: >> On Thu, Oct 10, 2013 at 02:45:58PM +0200, Jens Renner wrote: >> >>> + of_property_read_u32(pdev->dev.of_node, >>> "xlnx,num-transfer-bits", >>> + &bits_per_word); >> >> This new property needs to be documented in the binding document (and >> sent to the DT maintainers for review though in this case it's probably >> OK). > > So far there is no binding documentation for spi/xilinx at all, but I prepared > a file spi-xilinx.txt which documents everything. I will send it to the DT > maintainers.
In the normal Linux SPI layer, bits_per_word is a field for a spi_device (slave). Different slaves on the same master could use different bits per word values, which can be changed by the slave for different transfers. 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? 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. Anyway, the driver should use this device tree/platform data property to set the master's bits_per_word_mask field. Then you can remove the bits_per_word checking code from the driver (in xilinx_spi_setup_transfer()) since the spi core will do it for you. BTW, you might consider what happens if a new version of the IP supports multiple bits_per_words when deciding on how the DT property should be design. Maybe a list of values or a mask? ------------------------------------------------------------------------------ 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
