On Mon, Feb 06, 2017 at 08:20:35AM +0100, Andrea Merello wrote: > On Sun, Feb 5, 2017 at 6:38 AM, Vinod Koul <vinod.koul@xxxxxxxxx> wrote: > > On Fri, Jan 20, 2017 at 04:32:49PM +0100, Andrea Merello wrote: > >> Signed-off-by: Andrea Merello <andrea.merello@xxxxxxxxx> > >> --- > >> Documentation/devicetree/bindings/dma/xilinx/xilinx_dma.txt | 3 +++ > >> 1 file changed, 3 insertions(+) > >> > >> diff --git a/Documentation/devicetree/bindings/dma/xilinx/xilinx_dma.txt b/Documentation/devicetree/bindings/dma/xilinx/xilinx_dma.txt > >> index 2897e6d..71d31f9 100644 > >> --- a/Documentation/devicetree/bindings/dma/xilinx/xilinx_dma.txt > >> +++ b/Documentation/devicetree/bindings/dma/xilinx/xilinx_dma.txt > >> @@ -34,6 +34,9 @@ Required properties: > >> Optional elements: "m_axi_mm2s_aclk", "m_axi_s2mm_aclk", > >> "m_axi_sg_aclk" > >> > >> +Required properties for AXI DMA: > >> +- xlnx,lengthregwidth: Should be the width of the length register as configured in h/w. > > > > Ah it should be before the patch you are using it! > > ah, OK > > > Now, what happens on older firmware where this property is not there.. > > Yes, it does refuse to load.. But al least, instead of behaving > incorrectly due to the driver assuming the HW has a certain maximum > transfer length that might not match the real one, we get a message > that tell us to add this property. > > I thought it was acceptable to introduce a new mandatory property > because I've already seen changes like this (IIRC was about I2C > clocks), if this is not the case I can just spit a warning and stick > with the old default value in case the prop is missing.. I am not sure about that part, IIUC ABI treats this as regression. ABIs are supposed to be backward compatible. > > > Also CC DT folks on all DT related changes > > OK. Lets hear from Rob as well on this -- ~Vinod -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
