On Friday 31 August 2012, Stephen Boyd wrote:

quoted

+static int hvc_dcc_put_chars_v6(uint32_t vt, const char *buf, int count)
+{
+     int i;
+
+     for (i = 0; i < count; i++) {
+             while (__dcc_getstatus_v6() & DCC_STATUS_TX_V6)
+                     cpu_relax();
+
+             __dcc_putchar_v6(buf[i]);
+     }
+
+     return count;
+}

It's unfortunate that the main logic is duplicated. I wonder if we could
push the runtime decision slightly lower into the accessor functions
instead and make some new functions dcc_tx_busy() and dcc_rx_busy() or
something. Then these loops stay the same.

Agreed. Ideally, you should be able to get the code to be compiled into
the same binary as before for ARMv6+. If only the inline assembly differs,
you can do something like

static inline char __dcc_getchar(void)
{
        char __c;

        if (__LINUX_ARM_ARCH >= 6)
		asm volatile("mrc p14, 0, %0, c0, c5, 0 @ read comms data reg"
	                : "=r" (__c));
	else
		asm volatile ("mrc p14, 0, %0, c1, c0  @ read comms data reg"
			: "=r" (ret));
        isb();

        return __c;
}

	Arnd