On Fri, May 23, 2014 at 10:08:49AM -0700, Prasad Koya wrote: > > I don't see anyone in kernel using UART_IIR_BUSY bit except Designware > serial driver. We are using 8250 driver for our 16550A and > occasionally we see UART_IIR_BUSY set and soon after that console is > hosed. In what situations is this bit set? I don't see much > documentation for this. UART_IIR_BUSY is not a bit, it's a magic bit pattern, which is I believe a Designware-specific hack. As far as standard 8250-compatible UART's are concerned, if the low bit (bit 0) is set in the IIR register, there are no interrupts pending, and so you shouldn't need to check the 0x06 bits (i.e., bits 1 and 2). - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
