Russell King wrote:
> On Tue, Jul 05, 2005 at 03:19:40PM +0100, David Vrabel wrote:
> 
>>The 8250 serial driver detects the Exar XR16L2551 as a 16550A.  The
>>XR16L2551 has an EFR register and sleep capabilities (UART_CAP_FIFO |
>>UART_CAP_EFR | UART_CAP_SLEEP).  However, broken_efr() thinks it's a
>>buggy Exar ST16C255x.
>>
>>...
>>
>>Also, the initial IER test was failing (after a soft reboot) with the
>>XR16L2551 part since the sleep mode bit was set but was read-only.  It
>>seems sensible to make this test only look at the lower 4 bits.
> 
> ... or maybe this can be used to test for the buggy version.

I've redid the patch and added a check for this.  Alex, could you test
this version, please.

>>Index: linux-2.6-working/drivers/serial/8250.c
>>===================================================================
>>--- linux-2.6-working.orig/drivers/serial/8250.c	2005-07-04 13:43:13.000000000 +0100
>>+++ linux-2.6-working/drivers/serial/8250.c	2005-07-05 15:08:05.000000000 +0100
>>@@ -249,6 +249,14 @@
>> 		.fcr		= UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,
>> 		.flags		= UART_CAP_FIFO | UART_CAP_UUE,
>> 	},
>>+	[PORT_XR16550] = {
>>+		.name		= "XR16550",
>>+		.fifo_size	= 16,
>>+		.tx_loadsz	= 16,
>>+		.fcr		= UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_01 |
>>+				  UART_FCR_T_TRIG_00,
> 
> 
> The docs I've just pulled of Exar's site imply that the XR16L2551
> doesn't have a transmit trigger threshold, so UART_FCR_T_TRIG_00
> shouldn't be specified here.  Also, is there a reason for restricting
> the RX trigger level to 4 instead of 8 bytes?

That's a cut-n-paste mistake.  It should be like the 16550A.

David Vrabel
-- 
David Vrabel, Design Engineer

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