linux-kernel - [PATCH 1/2] MIPS: jazz: always allow little-endian builds

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Date:   Fri, 22 Jan 2021 12:02:50 +0100
From:   Arnd Bergmann <arnd@...nel.org>
To:     Thomas Bogendoerfer <tsbogend@...ha.franken.de>
Cc:     Arnd Bergmann <arnd@...db.de>, kernel test robot <lkp@...el.com>,
        Jiaxun Yang <jiaxun.yang@...goat.com>,
        Paul Cercueil <paul@...pouillou.net>,
        Paul Burton <paulburton@...nel.org>,
        linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] MIPS: jazz: always allow little-endian builds

From: Arnd Bergmann <arnd@...db.de>

The kernel test robot keeps reporting the same bug when it
shows up in new files after random unrelated patches:

In file included from arch/mips/include/uapi/asm/byteorder.h:13,
                 from arch/mips/include/asm/bitops.h:20,
                 from include/linux/bitops.h:26,
                 from include/linux/kernel.h:12,
                 from include/linux/clk.h:13,
                 from drivers/base/regmap/regmap-mmio.c:7:
include/linux/byteorder/big_endian.h:8:2: warning: #warning inconsistent configuration, needs CONFIG_CPU_BIG_ENDIAN [-Wcpp]
    8 | #warning inconsistent configuration, needs CONFIG_CPU_BIG_ENDIAN
      |  ^~~~~~~
drivers/base/regmap/regmap-mmio.c: In function 'regmap_mmio_gen_context':
>> drivers/base/regmap/regmap-mmio.c:274:2: error: duplicate case value
  274 |  case REGMAP_ENDIAN_NATIVE:
      |  ^~~~
drivers/base/regmap/regmap-mmio.c:246:2: note: previously used here
  246 |  case REGMAP_ENDIAN_NATIVE:

The problem is that some randconfig builds end up on the MIPS jazz
platform with neither CONFIG_CPU_BIG_ENDIAN nor CONFIG_CPU_LITTLE_ENDIAN
because no specific machine is selected. As it turns out, all jazz
machines support little-endian kernels, so this can simply be allowed
globally.

Reported-by: kernel test robot <lkp@...el.com>
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
The configuration used by lkp here showed two other unrelated bugs,
one of which I'm addressing in another patch. The one I'm not
addressing is that 32-bit JAZZ with hugepages and 4K pages triggers
BUILD_BUG_ON(IS_ENABLED(CONFIG_32BIT) && (_PFN_SHIFT > PAGE_SHIFT)).
---
 arch/mips/Kconfig      | 1 +
 arch/mips/jazz/Kconfig | 3 ---
 2 files changed, 1 insertion(+), 3 deletions(-)

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 2000bb2b0220..e6bd1eee70f2 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -406,6 +406,7 @@ config MACH_JAZZ
 	select SYS_SUPPORTS_32BIT_KERNEL
 	select SYS_SUPPORTS_64BIT_KERNEL
 	select SYS_SUPPORTS_100HZ
+	select SYS_SUPPORTS_LITTLE_ENDIAN
 	help
 	  This a family of machines based on the MIPS R4030 chipset which was
 	  used by several vendors to build RISC/os and Windows NT workstations.
diff --git a/arch/mips/jazz/Kconfig b/arch/mips/jazz/Kconfig
index 06838f80a5d7..42932ca98db9 100644
--- a/arch/mips/jazz/Kconfig
+++ b/arch/mips/jazz/Kconfig
@@ -3,7 +3,6 @@ config ACER_PICA_61
 	bool "Support for Acer PICA 1 chipset"
 	depends on MACH_JAZZ
 	select DMA_NONCOHERENT
-	select SYS_SUPPORTS_LITTLE_ENDIAN
 	help
 	  This is a machine with a R4400 133/150 MHz CPU. To compile a Linux
 	  kernel that runs on these, say Y here. For details about Linux on
@@ -15,7 +14,6 @@ config MIPS_MAGNUM_4000
 	depends on MACH_JAZZ
 	select DMA_NONCOHERENT
 	select SYS_SUPPORTS_BIG_ENDIAN
-	select SYS_SUPPORTS_LITTLE_ENDIAN
 	help
 	  This is a machine with a R4000 100 MHz CPU. To compile a Linux
 	  kernel that runs on these, say Y here. For details about Linux on
@@ -26,7 +24,6 @@ config OLIVETTI_M700
 	bool "Support for Olivetti M700-10"
 	depends on MACH_JAZZ
 	select DMA_NONCOHERENT
-	select SYS_SUPPORTS_LITTLE_ENDIAN
 	help
 	  This is a machine with a R4000 100 MHz CPU. To compile a Linux
 	  kernel that runs on these, say Y here. For details about Linux on
-- 
2.29.2