On 06/01/2013 09:29 AM, Olof Johansson wrote:

On Fri, May 31, 2013 at 05:19:02PM +0530, Tushar Behera wrote:

quoted

Printing low-level debug messages make an assumption that the specified
UART port has been preconfigured by the bootloader. Incorrectly
specified UART port results in system getting stalled while printing the
message "Uncompressing Linux... done, booting the kernel"

This UART port number is specified through S3C_LOWLEVEL_UART_PORT. Since
the UART port might different for different board, it is not possible to
specify it correctly for every board that use a common defconfig file.

Calling this print subroutine only when DEBUG_LL fixes the problem. By
disabling DEBUG_LL in default config file, we would be able to boot
multiple boards with different default UART ports.

With this current approach, we miss the print "Uncompressing Linux...
done, booting the kernel." when DEBUG_LL is not defined.

Signed-off-by: Tushar Behera <redacted>
---
 arch/arm/mach-exynos/include/mach/uncompress.h  |   11 ++++++++---
 arch/arm/plat-samsung/include/plat/uncompress.h |   10 +++++++++-
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/arch/arm/mach-exynos/include/mach/uncompress.h b/arch/arm/mach-exynos/include/mach/uncompress.h
index 2979995..730f69f 100644
--- a/arch/arm/mach-exynos/include/mach/uncompress.h
+++ b/arch/arm/mach-exynos/include/mach/uncompress.h

@@ -37,11 +37,16 @@ static void arch_detect_cpu(void)
 	chip_id >>= 20;
 	chip_id &= 0xf;
 
+#ifdef CONFIG_DEBUG_LL
 	if (chip_id == 0x5)
-		uart_base = (volatile u8 *)EXYNOS5_PA_UART + (S3C_UART_OFFSET * CONFIG_S3C_LOWLEVEL_UART_PORT);
+		uart_base = (volatile u8 *)EXYNOS5_PA_UART +
+			(S3C_UART_OFFSET * CONFIG_S3C_LOWLEVEL_UART_PORT);
 	else
-		uart_base = (volatile u8 *)EXYNOS4_PA_UART + (S3C_UART_OFFSET * CONFIG_S3C_LOWLEVEL_UART_PORT);
-
+		uart_base = (volatile u8 *)EXYNOS4_PA_UART +
+			(S3C_UART_OFFSET * CONFIG_S3C_LOWLEVEL_UART_PORT);
+#else
+	uart_base = NULL;
+#endif

You can do:

	if (!config_enabled(CONFIG_DEBUG_LL))
		return;

Thanks for the hint.

Or rather, we calculate uart_base unconditionally in mach/uncompress.h
and replace check for uart_base with config_enabled(CONFIG_DEBUG_LL) in
plat/uncompress.h. That would get rid of all the ifdef's in the
mach/uncompress.h files.

Let me spin out another version with this change.

Since uart_base will be set to 0 by being in BSS anyway.


-Olof

-- 
Tushar Behera