linux-kernel - Re: [linux-review:James-Hogan/kbuild-Remove-stale-asm-generic-wrappers/20160119-183642] d979f99e9cc14e2667e9b6e268db695977e4197a BUILD DONE

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Message-ID: <19656457.qoKNGRmV4Q@wuerfel>
Date:	Fri, 29 Jan 2016 21:44:13 +0100
From:	Arnd Bergmann <arnd@...db.de>
To:	Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:	Russell King - ARM Linux <linux@....linux.org.uk>,
	Fengguang Wu <fengguang.wu@...el.com>,
	Linux-Arch <linux-arch@...r.kernel.org>,
	Linux MIPS Mailing List <linux-mips@...ux-mips.org>,
	James Hogan <james.hogan@...tec.com>,
	Paul Burton <paul.burton@...tec.com>,
	linux-kbuild <linux-kbuild@...r.kernel.org>,
	Heinrich Schuchardt <xypron.glpk@....de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Ralf Baechle <ralf@...ux-mips.org>,
	Florian Fainelli <f.fainelli@...il.com>,
	Michal Marek <mmarek@...e.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [linux-review:James-Hogan/kbuild-Remove-stale-asm-generic-wrappers/20160119-183642] d979f99e9cc14e2667e9b6e268db695977e4197a BUILD DONE

On Friday 29 January 2016 09:01:31 Geert Uytterhoeven wrote:
> Hi Arnd,
> 
> On Fri, Jan 29, 2016 at 12:07 AM, Arnd Bergmann <arnd@...db.de> wrote:
> > The other related issue is the DEBUG_UART_{VIRT,PHYS} setting,
> > where there is no safe platform-specific default. I have two
> > ideas for working around that, maybe one of them sounds ok to
> > you:
> >
> > a) find a way to warn and/or disable DEBUG_LL when no address
> >    is set, rather than failing the build
> >
> > b) add 'default 0 if COMPILE_TEST' to make it harder to get this
> >    wrong by accident (hopefully nobody tries to run a COMPILE_TEST
> >    kernel). Also maybe add a #warning if DEBUG_UART_VIRT is
> 
> Make sure to add it at the end of the list, so enabling COMPILE_TEST in a
> working .config should give another working .config.

Sure, I've just done a largish series of patches in 4.5 to fix that
bug where we had it already.

> Perhaps you can use 0xdeadbeef instead of 0, and add
> 
>     #if DEBUG_UART_PHYS == 0xdeadbeed
>     #warning Broken value of DEBUG_UART_PHYS.
>     #endif
> 
> somewhere?

I can do that, though I don't see much of an advantage, as zero
is no more likely to be a real address than 0xdeadbeed.

How about the version below?

	Arnd

diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug
index c6b6175d0203..6cc09cf8618f 100644
--- a/arch/arm/Kconfig.debug
+++ b/arch/arm/Kconfig.debug
@@ -1526,6 +1526,7 @@ config DEBUG_UART_PHYS
 	default 0xfffb9800 if DEBUG_OMAP1UART3 || DEBUG_OMAP7XXUART3
 	default 0xfffe8600 if DEBUG_BCM63XX_UART
 	default 0xfffff700 if ARCH_IOP33X
+	default 0xdeadbeef if DEBUG_LL_UART_8250 || DEBUG_LL_UART_PL01X || DEBUG_LL_UART_EFM32
 	depends on ARCH_EP93XX || \
 	        DEBUG_LL_UART_8250 || DEBUG_LL_UART_PL01X || \
 		DEBUG_LL_UART_EFM32 || \
@@ -1628,6 +1629,7 @@ config DEBUG_UART_VIRT
 	default 0xff003000 if DEBUG_U300_UART
 	default 0xffd01000 if DEBUG_HIP01_UART
 	default DEBUG_UART_PHYS if !MMU
+	default 0xdeadbeef if DEBUG_LL_UART_8250 || DEBUG_LL_UART_PL01X || DEBUG_LL_UART_EFM32
 	depends on DEBUG_LL_UART_8250 || DEBUG_LL_UART_PL01X || \
 		DEBUG_UART_8250 || DEBUG_UART_PL01X || DEBUG_MESON_UARTAO || \
 		DEBUG_NETX_UART || \
diff --git a/arch/arm/include/debug/8250.S b/arch/arm/include/debug/8250.S
index 7f7446f6f806..1191b1458586 100644
--- a/arch/arm/include/debug/8250.S
+++ b/arch/arm/include/debug/8250.S
@@ -9,6 +9,9 @@
  */
 #include <linux/serial_reg.h>
 
+#if CONFIG_DEBUG_UART_PHYS == 0xdeadbeef || CONFIG_DEBUG_UART_VIRT < 0xe0000000
+#include "none.S"
+#else
 		.macro	addruart, rp, rv, tmp
 		ldr	\rp, =CONFIG_DEBUG_UART_PHYS
 		ldr	\rv, =CONFIG_DEBUG_UART_VIRT
@@ -55,3 +58,5 @@
 		beq	1001b
 #endif
 		.endm
+
+#endif
diff --git a/arch/arm/include/debug/efm32.S b/arch/arm/include/debug/efm32.S
index 660fa1e4b77b..537021761e4a 100644
--- a/arch/arm/include/debug/efm32.S
+++ b/arch/arm/include/debug/efm32.S
@@ -6,6 +6,9 @@
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */
+#if CONFIG_DEBUG_UART_PHYS == 0xdeadbeef || CONFIG_DEBUG_UART_VIRT < 0xf0000000
+#include "none.S"
+#else
 
 #define UARTn_CMD		0x000c
 #define UARTn_CMD_TXEN			0x0004
@@ -43,3 +46,5 @@
 		tst	\rd, #UARTn_STATUS_TXC
 		bne	1001b
 		.endm
+
+#endif
diff --git a/arch/arm/include/debug/none.S b/arch/arm/include/debug/none.S
new file mode 100644
index 000000000000..75cd1bbee5c4
--- /dev/null
+++ b/arch/arm/include/debug/none.S
@@ -0,0 +1,16 @@
+
+#warning DEBUG_LL not configured, disabling
+
+		.macro	addruart, rp, rv, tmp
+		ldr	\rp, =0
+		ldr	\rv, =0
+		.endm
+
+		.macro	senduart,rd,rx
+		.endm
+
+		.macro	busyuart,rd,rx
+		.endm
+
+		.macro	waituart,rd,rx
+		.endm
diff --git a/arch/arm/include/debug/pl01x.S b/arch/arm/include/debug/pl01x.S
index f7d8323cefcc..fbe0cad32be0 100644
--- a/arch/arm/include/debug/pl01x.S
+++ b/arch/arm/include/debug/pl01x.S
@@ -10,6 +10,9 @@
  * published by the Free Software Foundation.
  *
 */
+#if CONFIG_DEBUG_UART_PHYS == 0xdeadbeef || CONFIG_DEBUG_UART_VIRT < 0xf0000000
+#include "none.S"
+#else
 #include <linux/amba/serial.h>
 
 #ifdef CONFIG_DEBUG_ZTE_ZX
@@ -43,3 +46,4 @@
 		tst	\rd, #UART01x_FR_BUSY
 		bne	1001b
 		.endm
+#endif