ARM: CPU hotplug: fix hard-coded control register constants

5 messages, 4 authors, 2011-01-15 · open the first message on its own page

ARM: CPU hotplug: fix hard-coded control register constants

From: viresh kumar <hidden>
Date: 2011-01-14 11:50:03

Russell,

I was just tracking latest changes in realview, for preparing SPEAr
support V4. I found below patch and didn't understood it very well.

quoted hunk

Subject: [PATCH] ARM: CPU hotplug: fix hard-coded control register constants

Use the definition we've provided in asm/system.h rather than
numeric constants.

Signed-off-by: Russell King <redacted>
---
 arch/arm/mach-realview/hotplug.c |    8 ++++----
 arch/arm/mach-s5pv310/hotplug.c  |    8 ++++----
 arch/arm/mach-tegra/hotplug.c    |    8 ++++----
 3 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/arch/arm/mach-realview/hotplug.c b/arch/arm/mach-realview/hotplug.c
index b6387cf..a87523d 100644
--- a/arch/arm/mach-realview/hotplug.c
+++ b/arch/arm/mach-realview/hotplug.c

@@ -31,10 +31,10 @@ static inline void cpu_enter_lowpower(void)
 	"	bic	%0, %0, #0x20\n"
 	"	mcr	p15, 0, %0, c1, c0, 1\n"
 	"	mrc	p15, 0, %0, c1, c0, 0\n"
-	"	bic	%0, %0, #0x04\n"
+	"	bic	%0, %0, %2\n"
 	"	mcr	p15, 0, %0, c1, c0, 0\n"
 	  : "=&r" (v)
-	  : "r" (0)
+	  : "r" (0), "Ir" (CR_C)
 	  : "cc");
 }

This looks fine as you have replaced 0x04 with CR_C, which itself is (1 << 2).

quoted hunk

@@ -43,13 +43,13 @@ static inline void cpu_leave_lowpower(void)
 	unsigned int v;
 
 	asm volatile(	"mrc	p15, 0, %0, c1, c0, 0\n"
-	"	orr	%0, %0, #0x04\n"
+	"	orr	%0, %0, %1\n"
 	"	mcr	p15, 0, %0, c1, c0, 0\n"
 	"	mrc	p15, 0, %0, c1, c0, 1\n"
 	"	orr	%0, %0, #0x20\n"
 	"	mcr	p15, 0, %0, c1, c0, 1\n"
 	  : "=&r" (v)
-	  :
+	  : "Ir" (CR_C)
 	  : "cc");
 }

fine here also.

quoted hunk

diff --git a/arch/arm/mach-s5pv310/hotplug.c b/arch/arm/mach-s5pv310/hotplug.c
index 951ba6d..afa5392 100644
--- a/arch/arm/mach-s5pv310/hotplug.c
+++ b/arch/arm/mach-s5pv310/hotplug.c

@@ -30,13 +30,13 @@ static inline void cpu_enter_lowpower(void)
 	 * Turn off coherency
 	 */
 	"	mrc	p15, 0, %0, c1, c0, 1\n"
-	"	bic	%0, %0, #0x20\n"
+	"	bic	%0, %0, %2\n"

but why replace 0x20 with CR_C instead of CR_D

quoted hunk

 	"	mcr	p15, 0, %0, c1, c0, 1\n"
 	"	mrc	p15, 0, %0, c1, c0, 0\n"
 	"	bic	%0, %0, #0x04\n"
 	"	mcr	p15, 0, %0, c1, c0, 0\n"
 	  : "=&r" (v)
-	  : "r" (0)
+	  : "r" (0), "Ir" (CR_C)
 	  : "cc");
 }

@@ -46,13 +46,13 @@ static inline void cpu_leave_lowpower(void)
 
 	asm volatile(
 	"mrc	p15, 0, %0, c1, c0, 0\n"
-	"	orr	%0, %0, #0x04\n"
+	"	orr	%0, %0, %1\n"
 	"	mcr	p15, 0, %0, c1, c0, 0\n"
 	"	mrc	p15, 0, %0, c1, c0, 1\n"
 	"	orr	%0, %0, #0x20\n"
 	"	mcr	p15, 0, %0, c1, c0, 1\n"
 	  : "=&r" (v)
-	  :
+	  : "Ir" (CR_C)
 	  : "cc");
 }

diff --git a/arch/arm/mach-tegra/hotplug.c b/arch/arm/mach-tegra/hotplug.c
index 17faf77..a5cb1ce 100644
--- a/arch/arm/mach-tegra/hotplug.c
+++ b/arch/arm/mach-tegra/hotplug.c

@@ -26,13 +26,13 @@ static inline void cpu_enter_lowpower(void)
 	 * Turn off coherency
 	 */
 	"	mrc	p15, 0, %0, c1, c0, 1\n"
-	"	bic	%0, %0, #0x20\n"
+	"	bic	%0, %0, %2\n"

here also.

Was this code wrong earlier??

-- 
viresh

ARM: CPU hotplug: fix hard-coded control register constants

From: Russell King - ARM Linux <hidden>
Date: 2011-01-14 12:04:37

On Fri, Jan 14, 2011 at 05:20:03PM +0530, viresh kumar wrote:

quoted

diff --git a/arch/arm/mach-s5pv310/hotplug.c b/arch/arm/mach-s5pv310/hotplug.c
index 951ba6d..afa5392 100644
--- a/arch/arm/mach-s5pv310/hotplug.c
+++ b/arch/arm/mach-s5pv310/hotplug.c

@@ -30,13 +30,13 @@ static inline void cpu_enter_lowpower(void)
 	 * Turn off coherency
 	 */
 	"	mrc	p15, 0, %0, c1, c0, 1\n"
-	"	bic	%0, %0, #0x20\n"
+	"	bic	%0, %0, %2\n"

but why replace 0x20 with CR_C instead of CR_D

Looks like a mistake - it should've been the one below.

quoted

 	"	mcr	p15, 0, %0, c1, c0, 1\n"
 	"	mrc	p15, 0, %0, c1, c0, 0\n"
 	"	bic	%0, %0, #0x04\n"
 	"	mcr	p15, 0, %0, c1, c0, 0\n"
 	  : "=&r" (v)
-	  : "r" (0)
+	  : "r" (0), "Ir" (CR_C)
 	  : "cc");

In any case, this code is probably doing the wrong thing - if s5pv310
is not an ARMv6 MPCore the its fiddling with the auxillary control
register is already broken.

quoted

diff --git a/arch/arm/mach-tegra/hotplug.c b/arch/arm/mach-tegra/hotplug.c
index 17faf77..a5cb1ce 100644
--- a/arch/arm/mach-tegra/hotplug.c
+++ b/arch/arm/mach-tegra/hotplug.c

@@ -26,13 +26,13 @@ static inline void cpu_enter_lowpower(void)
 	 * Turn off coherency
 	 */
 	"	mrc	p15, 0, %0, c1, c0, 1\n"
-	"	bic	%0, %0, #0x20\n"
+	"	bic	%0, %0, %2\n"

here also.

Same comment.

ARM: CPU hotplug: fix hard-coded control register constants

From: Russell King - ARM Linux <hidden>
Date: 2011-01-14 12:08:38

Here's the fix which restores the old (but probably still broken)
behaviour:

Subject: [PATCH] ARM: fix wrongly patched constants

e3d9c625 (ARM: CPU hotplug: fix hard-coded control register constants)
changed the wrong constants in the hotplug assembly code.  Fix this.

Reported-by: viresh kumar <redacted>
Signed-off-by: Russell King <redacted>
---
 arch/arm/mach-s5pv310/hotplug.c |    4 ++--
 arch/arm/mach-tegra/hotplug.c   |    4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/arm/mach-s5pv310/hotplug.c b/arch/arm/mach-s5pv310/hotplug.c
index afa5392..c24235c 100644
--- a/arch/arm/mach-s5pv310/hotplug.c
+++ b/arch/arm/mach-s5pv310/hotplug.c

@@ -30,10 +30,10 @@ static inline void cpu_enter_lowpower(void)
 	 * Turn off coherency
 	 */
 	"	mrc	p15, 0, %0, c1, c0, 1\n"
-	"	bic	%0, %0, %2\n"
+	"	bic	%0, %0, #0x20\n"
 	"	mcr	p15, 0, %0, c1, c0, 1\n"
 	"	mrc	p15, 0, %0, c1, c0, 0\n"
-	"	bic	%0, %0, #0x04\n"
+	"	bic	%0, %0, %2\n"
 	"	mcr	p15, 0, %0, c1, c0, 0\n"
 	  : "=&r" (v)
 	  : "r" (0), "Ir" (CR_C)

diff --git a/arch/arm/mach-tegra/hotplug.c b/arch/arm/mach-tegra/hotplug.c
index a5cb1ce..f329404 100644
--- a/arch/arm/mach-tegra/hotplug.c
+++ b/arch/arm/mach-tegra/hotplug.c

@@ -26,10 +26,10 @@ static inline void cpu_enter_lowpower(void)
 	 * Turn off coherency
 	 */
 	"	mrc	p15, 0, %0, c1, c0, 1\n"
-	"	bic	%0, %0, %2\n"
+	"	bic	%0, %0, #0x20\n"
 	"	mcr	p15, 0, %0, c1, c0, 1\n"
 	"	mrc	p15, 0, %0, c1, c0, 0\n"
-	"	bic	%0, %0, #0x04\n"
+	"	bic	%0, %0, %2\n"
 	"	mcr	p15, 0, %0, c1, c0, 0\n"
 	  : "=&r" (v)
 	  : "r" (0), "Ir" (CR_C)

-- 
1.6.2.5

ARM: CPU hotplug: fix hard-coded control register constants

From: Stephen Warren <hidden>
Date: 2011-01-14 18:40:12

Russell King wrote:

Sent: Friday, January 14, 2011 5:05 AM

On Fri, Jan 14, 2011 at 05:20:03PM +0530, viresh kumar wrote:
...
In any case, this code is probably doing the wrong thing - if s5pv310
is not an ARMv6 MPCore the its fiddling with the auxillary control
register is already broken.

quoted

diff --git a/arch/arm/mach-tegra/hotplug.c b/arch/arm/mach-tegra/hotplug.c
index 17faf77..a5cb1ce 100644
--- a/arch/arm/mach-tegra/hotplug.c
+++ b/arch/arm/mach-tegra/hotplug.c

@@ -26,13 +26,13 @@ static inline void cpu_enter_lowpower(void)
 	 * Turn off coherency
 	 */
 	"	mrc	p15, 0, %0, c1, c0, 1\n"
-	"	bic	%0, %0, #0x20\n"
+	"	bic	%0, %0, %2\n"

here also.

Same comment.

Just as an FYI, in various downstream trees, that file (for mach-tegra) has
been removed and replaced with completely different code. However, the
replacement isn't in the process of being upstreamed right yet. Specifically:

git://android.git.kernel.org/kernel/tegra.git

linux-tegra-2.6.37

cb8e70bd4fa41ea7ac66f01f7425943db99ac7d3
ARM: tegra: Add suspend and hotplug support

Hope this helps.

-- 
nvpublic

ARM: CPU hotplug: fix hard-coded control register constants

From: viresh kumar <hidden>
Date: 2011-01-15 14:35:49

On 1/14/11, Russell King - ARM Linux [off-list ref] wrote:

quoted hunk

Subject: [PATCH] ARM: fix wrongly patched constants

e3d9c625 (ARM: CPU hotplug: fix hard-coded control register constants)
changed the wrong constants in the hotplug assembly code.  Fix this.

Reported-by: viresh kumar <redacted>
Signed-off-by: Russell King <redacted>
---
 arch/arm/mach-s5pv310/hotplug.c |    4 ++--
 arch/arm/mach-tegra/hotplug.c   |    4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/arm/mach-s5pv310/hotplug.c

b/arch/arm/mach-s5pv310/hotplug.c
index afa5392..c24235c 100644

--- a/arch/arm/mach-s5pv310/hotplug.c
+++ b/arch/arm/mach-s5pv310/hotplug.c

@@ -30,10 +30,10 @@ static inline void cpu_enter_lowpower(void)
 	 * Turn off coherency
 	 */
 	"	mrc	p15, 0, %0, c1, c0, 1\n"
-	"	bic	%0, %0, %2\n"
+	"	bic	%0, %0, #0x20\n"
 	"	mcr	p15, 0, %0, c1, c0, 1\n"
 	"	mrc	p15, 0, %0, c1, c0, 0\n"
-	"	bic	%0, %0, #0x04\n"
+	"	bic	%0, %0, %2\n"
 	"	mcr	p15, 0, %0, c1, c0, 0\n"
 	  : "=&r" (v)
 	  : "r" (0), "Ir" (CR_C)

diff --git a/arch/arm/mach-tegra/hotplug.c b/arch/arm/mach-tegra/hotplug.c
index a5cb1ce..f329404 100644
--- a/arch/arm/mach-tegra/hotplug.c
+++ b/arch/arm/mach-tegra/hotplug.c

@@ -26,10 +26,10 @@ static inline void cpu_enter_lowpower(void)
 	 * Turn off coherency
 	 */
 	"	mrc	p15, 0, %0, c1, c0, 1\n"
-	"	bic	%0, %0, %2\n"
+	"	bic	%0, %0, #0x20\n"
 	"	mcr	p15, 0, %0, c1, c0, 1\n"
 	"	mrc	p15, 0, %0, c1, c0, 0\n"
-	"	bic	%0, %0, #0x04\n"
+	"	bic	%0, %0, %2\n"
 	"	mcr	p15, 0, %0, c1, c0, 0\n"
 	  : "=&r" (v)
 	  : "r" (0), "Ir" (CR_C)

Acked-by: Viresh Kumar <redacted>

`h`	back out one level
`j`	next message in thread
`k`	previous message in thread
`l`	drill in
`Esc`	close help / fold thread tree
`?`	toggle this help