[PATCH] msm: fix debug-macro.S build failure

[Nicolas Pitre]

On Thu, 28 Oct 2010, Russell King - ARM Linux wrote:

> On Thu, Oct 28, 2010 at 02:43:16PM -0400, Nicolas Pitre wrote:
> > On Thu, 28 Oct 2010, Russell King - ARM Linux wrote:
> > 
> > > On Thu, Oct 28, 2010 at 02:24:33PM -0400, Nicolas Pitre wrote:
> > > > On Thu, 28 Oct 2010, Daniel Walker wrote:
> > > > 
> > > > > This is what the function currently has,
> > > > > 
> > > > >         .macro  addruart, rp, rv
> > > > >         ldr     \rp, =MSM_DEBUG_UART_PHYS
> > > > >         ldr     \rv, =MSM_DEBUG_UART_BASE
> > > > >         .endm
> > > > > 
> > > > > So if we have a MSM_DEBUG_UART_PHYS and MSM_DEBUG_UART_BASE we're
> > > > > returning it. We don't actually have those values for all the boards
> > > > > tho. My understanding was that there are some generic arm changes
> > > > > needed, but I need to confirm that.
> > > > 
> > > > Just return 0 in both registers when you have nothing better to return.
> > > 
> > > That's not a good idea - it'll cause 512MB of 1:1 mappings to be setup
> > > at virtual location 0 using the IO flags, which may conflict on ARMv6+.
> > > A better idea would be to return 0xfff00000, which'll cause it to only
> > > populate the top-most 1MB.
> > 
> > Given that this a phony address, better test for 0 explicitly and skip 
> > the mapping as well as bailing out early from putchar, etc.
> 
> That could be 0 phys, which given there is no defined memory layout on
> ARM, I would not put it past someone to put a UART at phys location 0
> one day.

Who knows.  But in this case I think it is probably cleaner to just care 
about the virtual address, and do something like this:

diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
index dd6b369a..1174880 100644
--- a/arch/arm/kernel/head.S
+++ b/arch/arm/kernel/head.S
@@ -216,7 +216,8 @@ __create_page_tables:
 	 */
 	addruart r7, r3
 
-	mov	r3, r3, lsr #20
+	movs	r3, r3, lsr #20
+	beq	2f
 	mov	r3, r3, lsl #2
 
 	add	r0, r4, r3
@@ -231,7 +232,7 @@ __create_page_tables:
 	add	r3, r3, #1 << 20
 	teq	r0, r6
 	bne	1b
-
+2:
 #else /* CONFIG_DEBUG_ICEDCC */
 	/* we don't need any serial debugging mappings for ICEDCC */
 	ldr	r7, [r10, #PROCINFO_IO_MMUFLAGS] @ io_mmuflags
diff --git a/arch/arm/mach-msm/include/mach/debug-macro.S b/arch/arm/mach-msm/include/mach/debug-macro.S
index fbd5d90..d8ea859 100644
--- a/arch/arm/mach-msm/include/mach/debug-macro.S
+++ b/arch/arm/mach-msm/include/mach/debug-macro.S
@@ -39,4 +39,18 @@
 
 	.macro	busyuart,rd,rx
 	.endm
+
+#else
+
+	.macro	addruart, rp, rv
+	mov	\rv, #0
+	.endm
+
+	.macro	senduart,rd,rx
+	.endm
+	.macro	waituart,rd,rx
+	.endm
+	.macro	busyuart,rd,rx
+	.endm
+
 #endif


Nicolas