[PATCH mips-for-linux-next] MIPS: check for D$ line size and CONFIG_MIPS_L1_SHIFT

[PATCH mips-for-linux-next] MIPS: check for D$ line size and CONFIG_MIPS_L1_SHIFT

[Florian Fainelli]

When a platform overrides the dcache_line_size detection in its
cpu-features-override.h file, check that the value matches
(1 << CONFIG_MIPS_L1_SHIFT) to ensure both settings are correct.

Signed-off-by: Florian Fainelli <florian@openwrt.org>
---
 arch/mips/include/asm/cpu-features.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/mips/include/asm/cpu-features.h b/arch/mips/include/asm/cpu-features.h
index 6e70b03..9052fb9 100644
--- a/arch/mips/include/asm/cpu-features.h
+++ b/arch/mips/include/asm/cpu-features.h
@@ -279,6 +279,10 @@
 
 #ifndef cpu_dcache_line_size
 #define cpu_dcache_line_size()	cpu_data[0].dcache.linesz
+#else
+#if (cpu_dcache_line_size() != (1 << CONFIG_MIPS_L1_CACHE_SHIFT))
+#error "cpu_dcache_line_size does not match CONFIG_MIPS_L1_CACHE_SHIFT"
+#endif
 #endif
 #ifndef cpu_icache_line_size
 #define cpu_icache_line_size()	cpu_data[0].icache.linesz
-- 
1.8.3.2

[PATCH mips-for-linux-next] MIPS: check for D$ line size and CONFIG_MIPS_L1_SHIFT

[Florian Fainelli]

When a platform overrides the dcache_line_size detection in its
cpu-features-override.h file, check that the value matches
(1 << CONFIG_MIPS_L1_SHIFT) to ensure both settings are correct.

Signed-off-by: Florian Fainelli <florian@openwrt.org>
---
 arch/mips/include/asm/cpu-features.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/mips/include/asm/cpu-features.h b/arch/mips/include/asm/cpu-features.h
index 6e70b03..9052fb9 100644
--- a/arch/mips/include/asm/cpu-features.h
+++ b/arch/mips/include/asm/cpu-features.h
@@ -279,6 +279,10 @@
 
 #ifndef cpu_dcache_line_size
 #define cpu_dcache_line_size()	cpu_data[0].dcache.linesz
+#else
+#if (cpu_dcache_line_size() != (1 << CONFIG_MIPS_L1_CACHE_SHIFT))
+#error "cpu_dcache_line_size does not match CONFIG_MIPS_L1_CACHE_SHIFT"
+#endif
 #endif
 #ifndef cpu_icache_line_size
 #define cpu_icache_line_size()	cpu_data[0].icache.linesz
-- 
1.8.3.2

Re: [PATCH mips-for-linux-next] MIPS: check for D$ line size and CONFIG_MIPS_L1_SHIFT

[Ralf Baechle]

On Wed, Jan 15, 2014 at 11:05:22AM -0800, Florian Fainelli wrote:

> When a platform overrides the dcache_line_size detection in its
> cpu-features-override.h file, check that the value matches
> (1 << CONFIG_MIPS_L1_SHIFT) to ensure both settings are correct.

Conceptually wrong - the two values serve an entirely different purpose.
dcache_line_size is used for cache maintenance by the MIPS code while
CONFIG_MIPS_L1_SHIFT - which has to be a constant due to the way it's
being used - are being used to define L1_CACHE_SHIFT in <asm/cache.h>
which in turn is being used primarily to optimize the memory layout of
various structures for performance - and in case of IP27 we lie, set
L1_CACHE_SHIFT to 7 which is the size of the S-cache.

On top of that it breaks the ip27 build.

And while we're at it, the use of CONFIG_MIPS_L1_SHIFT in
arch/mips/kernel/vmlinux.lds.S is fishy - but it needs a constant and
this should be good enough for all users.

  Ralf

Re: [PATCH mips-for-linux-next] MIPS: check for D$ line size and CONFIG_MIPS_L1_SHIFT

[Florian Fainelli]

2014/1/22 Ralf Baechle <ralf@linux-mips.org>:
> On Wed, Jan 15, 2014 at 11:05:22AM -0800, Florian Fainelli wrote:
>
>> When a platform overrides the dcache_line_size detection in its
>> cpu-features-override.h file, check that the value matches
>> (1 << CONFIG_MIPS_L1_SHIFT) to ensure both settings are correct.
>
> Conceptually wrong - the two values serve an entirely different purpose.
> dcache_line_size is used for cache maintenance by the MIPS code while
> CONFIG_MIPS_L1_SHIFT - which has to be a constant due to the way it's
> being used - are being used to define L1_CACHE_SHIFT in <asm/cache.h>
> which in turn is being used primarily to optimize the memory layout of
> various structures for performance - and in case of IP27 we lie, set
> L1_CACHE_SHIFT to 7 which is the size of the S-cache.
>
> On top of that it breaks the ip27 build.
>
> And while we're at it, the use of CONFIG_MIPS_L1_SHIFT in
> arch/mips/kernel/vmlinux.lds.S is fishy - but it needs a constant and
> this should be good enough for all users.

Fair enough, feel free to revert these commits and fix vmlinux.lds.S
while at it.
-- 
Florian