On Saturday 13 August 2011 12:46:45 David Brown wrote: > > I'm not sure actually what is best to use here. I'm thinking that the > 'lite' identifier should perhaps go away. MSM's have two UARTS on > them, an older "simple" PIO type of UART, and a newer one that can do > DMA (called the hsuart for high-speed). The hsuart can also be used > in a non-DMA driver in a mostly compatible way with the old UART. > > For non-high-speed applications, the user will probably just want to > use the non-DMA driver. My question is then: if the device tree > describes it as > > compatible = "qcom,msm-hsuart", "qcom,msm-uart"; > > and one driver matches qcom,msm-hsuart and another matches > qcom,msm-uart, which driver will get used. Ideally, it would use the > earliest one in the list. > > If that's the case, I'll get rid of the -lite suffix and just make the > non-DMA driver compatible with the plain "qcom,msm-uart". I believe that unfortunately the answer is that the first driver that matches anything will get used. There are two possible ways that I can see to make it do what you want anyway: 1. In the probe function for the slow driver, you return an error when the device you get passed matches "qcom,msm-hsuart", possibly dependent on whether the other driver also got built. 2. You register one platform driver that handles both names and gives the device to just one of the two drivers. This would probably require linking the two drivers into the same module, or having the non-DMA speed driver just act as a library. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
