Am Donnerstag, den 15.02.2018, 11:00 +0200 schrieb Ran Shalit: > I actually asked about DMA, because I see that it is possible to send > urb using DMA allocated buffers or not (coherent and non-coherent) > usb_buffer_alloc(). > So, How can we actually know if I should use this API with a device or > not ? I mean, is it always possible to use the coherent buffer with > the device ? Hi, it is always possible to use usb_alloc_coherent() on a host. But it is generally not sensible. It is for buffers to be reused many times. In general use kmalloc() [once per buffer. That is a rule. You must not share them.] HTH Oliver -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
