On Tue, Sep 09, 2003 at 05:18:59PM +0100, Russell King wrote:

quoted

On Mon, Sep 08, 2003 at 01:54:31PM -0700, Tom Rini wrote:

quoted

Hello.  The following patches (vs 2.4 and 2.6) make the Startech UART
detection 'more correct'  The problem is that on with the Motorola
MPC82xx line (8245 for example) it has an internal DUART that it 
claims
to be PC16550D compatible, and it has an additional EFR (Enhanced
Feature Register) at offset 0x2, like on the Startech UARTS.  
However,
it is not a Startech, and when it's detected as such, FIFOs don't 
work.
The fix for this is that the Startech UARTs have a 32 byte FIFO [1] 
and
the MPC82xx DUARTs have a 16-byte FIFO [2], to check that the FIFO 
size
is correct for a Startech.

size_fifo() is claimed to be unreliable at detecting the FIFO size,
so I don't feel safe about using it here.

I'd suggest something like:

	serial_outp(port, UART_LCR, UART_LCR_DLAB);
	efr = serial_in(port, UART_EFR);
	if ((efr & 0xfc) == 0) {
		serial_out(port, UART_EFR, 0xac | (efr & 3));
		/* if top 6 bits return zero, its motorola */
		if (serial_in(port, UART_EFR) == (efr & 3)) {
			/* motorola port */
		} else {
			/* ST16C650V1 port */
		}
		/* restore old value */
		serial_outb(port, UART_EFR, efr);
	}

Okay, from Kumar Gala (cc'ed) I've got the following patch for 2.4:
===== drivers/char/serial.c 1.34 vs edited =====

--- 1.34/drivers/char/serial.c	Sun Jul  6 22:33:28 2003
+++ edited/drivers/char/serial.c	Tue Sep  9 16:50:22 2003

@@ -3741,7 +3741,10 @@
 		/* Check for Startech UART's */
 		serial_outp(info, UART_LCR, UART_LCR_DLAB);
 		if (serial_in(info, UART_EFR) == 0) {
-			state->type = PORT_16650;
+			serial_outp(info, UART_EFR, 0xA8);
+			if (serial_in(info, UART_EFR) != 0)
+				state->type = PORT_16650;
+			serial_outp(info, UART_EFR, 0);
 		} else {
 			serial_outp(info, UART_LCR, 0xBF);
 			if (serial_in(info, UART_EFR) == 0)

And I forward ported this up to 2.6 as:
===== drivers/serial/8250.c 1.36 vs edited =====

--- 1.36/drivers/serial/8250.c	Tue Sep  9 07:22:12 2003
+++ edited/drivers/serial/8250.c	Tue Sep  9 16:49:07 2003

@@ -469,8 +469,13 @@
 	 */
 	serial_outp(up, UART_LCR, UART_LCR_DLAB);
 	if (serial_in(up, UART_EFR) == 0) {
-		DEBUG_AUTOCONF("EFRv1 ");
-		up->port.type = PORT_16650;
+		serial_outp(up, UART_EFR, 0xA8);
+		if (serial_in(up, UART_EFR) != 0) {
+			DEBUG_AUTOCONF("EFRv1 ");
+			up->port.type = PORT_16650;
+		} else
+			DEBUG_AUTOCONF("Motorola 8xxx DUART ");
+		serial_outp(up, UART_EFR, 0);
 		return;
 	}

Better?

-- 
Tom Rini
http://gate.crashing.org/~trini/
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