On Tue, 31 Oct 2017, Russell King - ARM Linux wrote:

On Tue, Oct 31, 2017 at 01:06:35PM -0400, Nicolas Pitre wrote:

quoted

That's easy to veryfy with this patch:

Unfortunately not that easy, this patch breaks printch.

Right, missed that.

New patch below:

diff --git a/arch/arm/kernel/debug.S b/arch/arm/kernel/debug.S
index ea9646cc2a..0d1cef4b6e 100644
--- a/arch/arm/kernel/debug.S
+++ b/arch/arm/kernel/debug.S

@@ -79,25 +79,28 @@ hexbuf:		.space 16
 
 ENTRY(printascii)
 		addruart_current r3, r1, r2
-		b	2f
-1:		waituart r2, r3
-		senduart r1, r3
-		busyuart r2, r3
-		teq	r1, #'\n'
-		moveq	r1, #'\r'
-		beq	1b
-2:		teq	r0, #0
+1:		teq	r0, #0
 		ldrneb	r1, [r0], #1
 		teqne	r1, #0
-		bne	1b
-		ret	lr
+		reteq	lr
+		teq     r1, #'\n'
+		bne	2f
+		mov	r1, '\r'
+		waituart r2, r3
+		senduart r1, r3
+		busyuart r2, r3
+		mov	r1, '\n'
+2:		waituart r2, r3
+		senduart r1, r3
+		busyuart r2, r3
+		b	1b
 ENDPROC(printascii)
 
 ENTRY(printch)
 		addruart_current r3, r1, r2
 		mov	r1, r0
 		mov	r0, #0
-		b	1b
+		b	2b
 ENDPROC(printch)
 
 #ifdef CONFIG_MMU

quoted

diff --git a/arch/arm/kernel/debug.S b/arch/arm/kernel/debug.S
index ea9646cc2a..40023a4871 100644
--- a/arch/arm/kernel/debug.S
+++ b/arch/arm/kernel/debug.S

@@ -79,18 +79,21 @@ hexbuf:		.space 16
 

The new code is:

quoted

 ENTRY(printascii)
 		addruart_current r3, r1, r2
+1:		teq	r0, #0
 		ldrneb	r1, [r0], #1
 		teqne	r1, #0
+		reteq	lr
+		teq     r1, #'\n'
+		bne	2f
+		mov	r1, '\r'
+		waituart r2, r3
+		senduart r1, r3
+		busyuart r2, r3
+		mov	r1, '\n'
+2:		waituart r2, r3
+		senduart r1, r3
+		busyuart r2, r3
+		b	1b
 ENDPROC(printascii)

and printch jumps to the 1: label with r0 = 0 and r1 = character.  Your
change has the effect that the "reteq" will always be taken when called
by printch.

-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line in suburbia: sync at 8.8Mbps down 630kbps up
According to speedtest.net: 8.21Mbps down 510kbps up