[LinuxBIOS] [Patch] AMD cs5536 uart disable - coreboot

31 May 2007

The UART disable code was causing a hang and was worked around with a 
return that skipped the disable code. This patch removes the return and 
fixes the UART disable code.
The problem was that the disable code was ORing bits into the Legacy_IO 
MSR causing issues with the LPC SIOs init code that would manifest as a 
hang because the IO would not be decoded correctly. ANDing to clear the 
bits fixes the issue.
Signed-off-by: Marc Jones marc.jones@amd.com
-- 
Marc Jones
Senior Software Engineer
(970) 226-9684 Office
mailto:Marc.Jones@amd.com
http://www.amd.com/embeddedprocessors

Index: cs5536.c
===================================================================

--- cs5536.c	(revision 2705)
+++ cs5536.c	(working copy)
@@ -316,9 +316,6 @@

    } else {
    	/* Reset and disable COM1 */
-		printk_err("Not disabling COM1 due to a bug ...\n");
-		/* for now, don't do this! */
-		return;
    	msr = rdmsr(MDD_UART1_CONF);
    	msr.lo = 1;	// reset
    	wrmsr(MDD_UART1_CONF, msr);
@@ -327,7 +324,7 @@

    	/* Disable the IRQ */
    	msr = rdmsr(MDD_LEG_IO);
-		msr.lo |= ~(0xF << 16);
+		msr.lo &= ~(0xF << 16);
    	wrmsr(MDD_LEG_IO, msr);
    }

@@ -391,7 +388,7 @@

    	/* Disable the IRQ */
    	msr = rdmsr(MDD_LEG_IO);
-		msr.lo |= ~(0xF << 20);
+		msr.lo &= ~(0xF << 20);
    	wrmsr(MDD_LEG_IO, msr);
    }
 }

    