[PATCH 0/6] Miscellaneous patches for 3.1 and 3.2

[PATCH 0/6] Miscellaneous patches for 3.1 and 3.2

[Will Deacon]

Hello,

This is a bit of a strange mix of patches that I've got lying around on
top of -rc1.

The following patches are fixes and I'd like to put them into Russell's
patch system in the near future:

  ARM: realview: ensure visibility of writes during reset
  ARM: twd: register clockevents device before enabling PPI
  ARM: cache: detect VIPT aliasing I-cache on ARMv6

The other patches can wait until closer to the next merge window and I'd
welcome any feedback on those. The boot CPU number patch is probably the
most controversial given that I doubt many platforms can support booting
on anything other than CPU0 (although my Realview-PBX is happy enough).

Will


Will Deacon (6):
  ARM: vexpress: determine active tile site before reading tile ID
  ARM: realview: ensure visibility of writes during reset
  ARM: twd: register clockevents device before enabling PPI
  ARM: smp: set thread_info->cpu to hardware CPU number for boot thread
  ARM: cache: detect VIPT aliasing I-cache on ARMv6
  ARM: cache: detect PIPT I-cache using CTR

 arch/arm/include/asm/cachetype.h                  |    5 +++-
 arch/arm/kernel/setup.c                           |   30 ++++++++++++++------
 arch/arm/kernel/smp.c                             |   16 +++++++++++
 arch/arm/kernel/smp_twd.c                         |    4 +-
 arch/arm/mach-realview/include/mach/system.h      |    1 +
 arch/arm/mach-vexpress/include/mach/motherboard.h |    5 +++
 arch/arm/mach-vexpress/v2m.c                      |    6 +++-
 7 files changed, 53 insertions(+), 14 deletions(-)

[PATCH 1/6] ARM: vexpress: determine active tile site before reading tile ID

[Will Deacon]

The Versatile Express platform features two tile sites and communicates
the active tile site via the SYS_MISC register on the motherboard.

This patch updates the tile detection code to read the ID for the
currently active tile during boot.

Signed-off-by: Will Deacon <will.deacon@arm.com>
---
 arch/arm/mach-vexpress/include/mach/motherboard.h |    5 +++++
 arch/arm/mach-vexpress/v2m.c                      |    6 ++++--
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/arch/arm/mach-vexpress/include/mach/motherboard.h b/arch/arm/mach-vexpress/include/mach/motherboard.h
index 0a3a375..163a22c 100644
--- a/arch/arm/mach-vexpress/include/mach/motherboard.h
+++ b/arch/arm/mach-vexpress/include/mach/motherboard.h
@@ -119,6 +119,11 @@ int v2m_cfg_write(u32 devfn, u32 data);
 int v2m_cfg_read(u32 devfn, u32 *data);
 
 /*
+ * Miscellaneous
+ */
+#define SYS_MISC_MASTERSITE	(1 << 14)
+
+/*
  * Core tile IDs
  */
 #define V2M_CT_ID_CA9		0x0c000191
diff --git a/arch/arm/mach-vexpress/v2m.c b/arch/arm/mach-vexpress/v2m.c
index 9e6b93b..dbb182c 100644
--- a/arch/arm/mach-vexpress/v2m.c
+++ b/arch/arm/mach-vexpress/v2m.c
@@ -389,10 +389,12 @@ static struct ct_desc *ct_descs[] __initdata = {
 static void __init v2m_populate_ct_desc(void)
 {
 	int i;
-	u32 current_tile_id;
+	u32 procid_reg, current_tile_id;
 
 	ct_desc = NULL;
-	current_tile_id = readl(MMIO_P2V(V2M_SYS_PROCID0)) & V2M_CT_ID_MASK;
+	procid_reg = readl(MMIO_P2V(V2M_SYS_MISC)) & SYS_MISC_MASTERSITE ?
+			V2M_SYS_PROCID1 : V2M_SYS_PROCID0;
+	current_tile_id = readl(MMIO_P2V(procid_reg)) & V2M_CT_ID_MASK;
 
 	for (i = 0; i < ARRAY_SIZE(ct_descs) && !ct_desc; ++i)
 		if (ct_descs[i]->id == current_tile_id)
-- 
1.7.0.4

[PATCH 2/6] ARM: realview: ensure visibility of writes during reset

[Will Deacon]

The various reset routines in mach-realview rely on an FPGA to
power-cycle the board after writing some magic runes to memory-mapped
registers.

This patch adds a dsb() following the writes, so that they become
visible before we mdelay(1000) in the arch_reset code. Without this
patch, the timeout would expire sporadically, causing the reset to fail.

Signed-off-by: Will Deacon <will.deacon@arm.com>
---
 arch/arm/mach-realview/include/mach/system.h |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/arch/arm/mach-realview/include/mach/system.h b/arch/arm/mach-realview/include/mach/system.h
index a30f2e3..6657ff2 100644
--- a/arch/arm/mach-realview/include/mach/system.h
+++ b/arch/arm/mach-realview/include/mach/system.h
@@ -44,6 +44,7 @@ static inline void arch_reset(char mode, const char *cmd)
 	 */
 	if (realview_reset)
 		realview_reset(mode);
+	dsb();
 }
 
 #endif
-- 
1.7.0.4

[PATCH 3/6] ARM: twd: register clockevents device before enabling PPI

[Will Deacon]

The smp_twd clockevents driver currently enables the local timer PPI
before the clockevents device is registered. This can lead to a kernel
panic if a spurious timer interrupt is generated before registration
has completed since the kernel will treat it as an IPI timer.

This patch moves the clockevents device registration before the IRQ
unmasking so that we can always handle timer interrupts once they can
occur.

Signed-off-by: Will Deacon <will.deacon@arm.com>
---
 arch/arm/kernel/smp_twd.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c
index 2c277d4..01c1862 100644
--- a/arch/arm/kernel/smp_twd.c
+++ b/arch/arm/kernel/smp_twd.c
@@ -137,8 +137,8 @@ void __cpuinit twd_timer_setup(struct clock_event_device *clk)
 	clk->max_delta_ns = clockevent_delta2ns(0xffffffff, clk);
 	clk->min_delta_ns = clockevent_delta2ns(0xf, clk);
 
+	clockevents_register_device(clk);
+
 	/* Make sure our local interrupt controller has this enabled */
 	gic_enable_ppi(clk->irq);
-
-	clockevents_register_device(clk);
 }
-- 
1.7.0.4

[PATCH 4/6] ARM: smp: set thread_info->cpu to hardware CPU number for boot thread

[Will Deacon]

On ARM, Linux assumes that the boot CPU has ID 0. If this ends up being
out of sync with the hardware CPU number, we will configure the GIC
incorrectly and route interrupts to the CPU with hardware ID 0.

This patch implements smp_setup_processor_id for ARM, using the MPIDR to
set the CPU of the boot thread.

Signed-off-by: Will Deacon <will.deacon@arm.com>
---
 arch/arm/kernel/smp.c |   16 ++++++++++++++++
 1 files changed, 16 insertions(+), 0 deletions(-)

diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index d88ff02..8e60a4f 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -259,6 +259,22 @@ void __ref cpu_die(void)
 }
 #endif /* CONFIG_HOTPLUG_CPU */
 
+void __init smp_setup_processor_id(void)
+{
+	u32 mpidr;
+
+	/* Read the MPIDR to find the hardware ID of the current CPU. */
+	asm("1:		mrc	p15, 0, %0, c0, c0, 5\n"
+	    "		.pushsection \".alt.smp.init\", \"a\"\n"
+	    "		.long	1b\n"
+	    "		mov	%0, #0\n"
+	    "		.popsection"
+	    : "=r" (mpidr));
+
+	current_thread_info()->cpu = mpidr & 0xff;
+	printk("Booting Linux on CPU %d\n", current_thread_info()->cpu);
+}
+
 /*
  * Called by both boot and secondaries to move global data into
  * per-processor storage.
-- 
1.7.0.4

[PATCH 5/6] ARM: cache: detect VIPT aliasing I-cache on ARMv6

[Will Deacon]

The current cache detection code does not check for an aliasing
I-cache if the D-cache is found to be VIPT aliasing.

This patch fixes the problem by always checking for an aliasing
I-cache on v6 and later.

Signed-off-by: Will Deacon <will.deacon@arm.com>
---
 arch/arm/kernel/setup.c |   15 ++++++++-------
 1 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index d95de69..2cdba13 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -280,18 +280,19 @@ static void __init cacheid_init(void)
 	if (arch >= CPU_ARCH_ARMv6) {
 		if ((cachetype & (7 << 29)) == 4 << 29) {
 			/* ARMv7 register format */
+			arch = CPU_ARCH_ARMv7;
 			cacheid = CACHEID_VIPT_NONALIASING;
 			if ((cachetype & (3 << 14)) == 1 << 14)
 				cacheid |= CACHEID_ASID_TAGGED;
-			else if (cpu_has_aliasing_icache(CPU_ARCH_ARMv7))
-				cacheid |= CACHEID_VIPT_I_ALIASING;
-		} else if (cachetype & (1 << 23)) {
-			cacheid = CACHEID_VIPT_ALIASING;
 		} else {
-			cacheid = CACHEID_VIPT_NONALIASING;
-			if (cpu_has_aliasing_icache(CPU_ARCH_ARMv6))
-				cacheid |= CACHEID_VIPT_I_ALIASING;
+			arch = CPU_ARCH_ARMv6;
+			if (cachetype & (1 << 23))
+				cacheid = CACHEID_VIPT_ALIASING;
+			else
+				cacheid = CACHEID_VIPT_NONALIASING;
 		}
+		if (cpu_has_aliasing_icache(arch))
+			cacheid |= CACHEID_VIPT_I_ALIASING;
 	} else {
 		cacheid = CACHEID_VIVT;
 	}
-- 
1.7.0.4

[PATCH 6/6] ARM: cache: detect PIPT I-cache using CTR

[Will Deacon]

The Cache Type Register L1Ip field identifies I-caches with a PIPT
policy using the encoding 11b.

This patch extends the cache policy parsing to identify PIPT I-caches
correctly and prevent them from being treated as VIPT aliasing in cases
where they are sufficiently large.

Signed-off-by: Will Deacon <will.deacon@arm.com>
---
 arch/arm/include/asm/cachetype.h |    5 ++++-
 arch/arm/kernel/setup.c          |   15 +++++++++++++--
 2 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/arch/arm/include/asm/cachetype.h b/arch/arm/include/asm/cachetype.h
index c023db0..7ea7814 100644
--- a/arch/arm/include/asm/cachetype.h
+++ b/arch/arm/include/asm/cachetype.h
@@ -7,6 +7,7 @@
 #define CACHEID_VIPT			(CACHEID_VIPT_ALIASING|CACHEID_VIPT_NONALIASING)
 #define CACHEID_ASID_TAGGED		(1 << 3)
 #define CACHEID_VIPT_I_ALIASING		(1 << 4)
+#define CACHEID_PIPT			(1 << 5)
 
 extern unsigned int cacheid;
 
@@ -16,6 +17,7 @@ extern unsigned int cacheid;
 #define cache_is_vipt_aliasing()	cacheid_is(CACHEID_VIPT_ALIASING)
 #define icache_is_vivt_asid_tagged()	cacheid_is(CACHEID_ASID_TAGGED)
 #define icache_is_vipt_aliasing()	cacheid_is(CACHEID_VIPT_I_ALIASING)
+#define icache_is_pipt()		cacheid_is(CACHEID_PIPT)
 
 /*
  * __LINUX_ARM_ARCH__ is the minimum supported CPU architecture
@@ -26,7 +28,8 @@ extern unsigned int cacheid;
 #if __LINUX_ARM_ARCH__ >= 7
 #define __CACHEID_ARCH_MIN	(CACHEID_VIPT_NONALIASING |\
 				 CACHEID_ASID_TAGGED |\
-				 CACHEID_VIPT_I_ALIASING)
+				 CACHEID_VIPT_I_ALIASING |\
+				 CACHEID_PIPT)
 #elif __LINUX_ARM_ARCH__ >= 6
 #define	__CACHEID_ARCH_MIN	(~CACHEID_VIVT)
 #else
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 2cdba13..6311da7 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -248,6 +248,10 @@ static int cpu_has_aliasing_icache(unsigned int arch)
 	int aliasing_icache;
 	unsigned int id_reg, num_sets, line_size;
 
+	/* PIPT caches never alias. */
+	if (icache_is_pipt())
+		return 0;
+
 	/* arch specifies the register format */
 	switch (arch) {
 	case CPU_ARCH_ARMv7:
@@ -282,8 +286,14 @@ static void __init cacheid_init(void)
 			/* ARMv7 register format */
 			arch = CPU_ARCH_ARMv7;
 			cacheid = CACHEID_VIPT_NONALIASING;
-			if ((cachetype & (3 << 14)) == 1 << 14)
+			switch (cachetype & (3 << 14)) {
+			case (1 << 14):
 				cacheid |= CACHEID_ASID_TAGGED;
+				break;
+			case (3 << 14):
+				cacheid |= CACHEID_PIPT;
+				break;
+			}
 		} else {
 			arch = CPU_ARCH_ARMv6;
 			if (cachetype & (1 << 23))
@@ -300,10 +310,11 @@ static void __init cacheid_init(void)
 	printk("CPU: %s data cache, %s instruction cache\n",
 		cache_is_vivt() ? "VIVT" :
 		cache_is_vipt_aliasing() ? "VIPT aliasing" :
-		cache_is_vipt_nonaliasing() ? "VIPT nonaliasing" : "unknown",
+		cache_is_vipt_nonaliasing() ? "PIPT / VIPT nonaliasing" : "unknown",
 		cache_is_vivt() ? "VIVT" :
 		icache_is_vivt_asid_tagged() ? "VIVT ASID tagged" :
 		icache_is_vipt_aliasing() ? "VIPT aliasing" :
+		icache_is_pipt() ? "PIPT" :
 		cache_is_vipt_nonaliasing() ? "VIPT nonaliasing" : "unknown");
 }
 
-- 
1.7.0.4

[PATCH 4/6] ARM: smp: set thread_info->cpu to hardware CPU number for boot thread

[Stephen Boyd]

On 08/08/2011 10:10 AM, Will Deacon wrote:
>
>  
> +void __init smp_setup_processor_id(void)
> +{
> +	u32 mpidr;
> +
> +	/* Read the MPIDR to find the hardware ID of the current CPU. */
> +	asm("1:		mrc	p15, 0, %0, c0, c0, 5\n"
> +	    "		.pushsection \".alt.smp.init\", \"a\"\n"
> +	    "		.long	1b\n"
> +	    "		mov	%0, #0\n"
> +	    "		.popsection"
> +	    : "=r" (mpidr));

Would it be a good idea to put this into asm/cputype.h? I suppose the
smp alternatives part would need to be written in C.

    mpidr = is_smp() ? read_cpuid_mpidr() : 0;

>
> +
> +	current_thread_info()->cpu = mpidr & 0xff;
> +	printk("Booting Linux on CPU %d\n", current_thread_info()->cpu);
> +}
> +

Should there be a KERN_INFO there?

-- 
Sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.

[PATCH 4/6] ARM: smp: set thread_info->cpu to hardware CPU number for boot thread

[Will Deacon]

On Mon, Aug 08, 2011 at 06:33:38PM +0100, Stephen Boyd wrote:
> On 08/08/2011 10:10 AM, Will Deacon wrote:
> >
> >  
> > +void __init smp_setup_processor_id(void)
> > +{
> > +	u32 mpidr;
> > +
> > +	/* Read the MPIDR to find the hardware ID of the current CPU. */
> > +	asm("1:		mrc	p15, 0, %0, c0, c0, 5\n"
> > +	    "		.pushsection \".alt.smp.init\", \"a\"\n"
> > +	    "		.long	1b\n"
> > +	    "		mov	%0, #0\n"
> > +	    "		.popsection"
> > +	    : "=r" (mpidr));
> 
> Would it be a good idea to put this into asm/cputype.h? I suppose the
> smp alternatives part would need to be written in C.
> 
>     mpidr = is_smp() ? read_cpuid_mpidr() : 0;

Yes, that's much better. We used to have asm/smp_mpidr.h which did this, so I
lifted the code from there but doing it in C is easier to read.

> >
> > +
> > +	current_thread_info()->cpu = mpidr & 0xff;
> > +	printk("Booting Linux on CPU %d\n", current_thread_info()->cpu);
> > +}
> > +
> 
> Should there be a KERN_INFO there?

Can be. I just followed suit with secondary_start_kernel, but smp.c doesn't
seem to be consistent anyway so I'll add the specifier.

Thanks for the comments,

Will

[PATCH 3/6] ARM: twd: register clockevents device before enabling PPI

[Marc Zyngier]

On 08/08/11 18:10, Will Deacon wrote:
> The smp_twd clockevents driver currently enables the local timer PPI
> before the clockevents device is registered. This can lead to a kernel
> panic if a spurious timer interrupt is generated before registration
> has completed since the kernel will treat it as an IPI timer.
> 
> This patch moves the clockevents device registration before the IRQ
> unmasking so that we can always handle timer interrupts once they can
> occur.
> 
> Signed-off-by: Will Deacon <will.deacon@arm.com>

Acked-by: Marc Zyngier <marc.zyngier@arm.com>

I'll rebase my timer patches on top of this one.

	M.
-- 
Jazz is not dead. It just smells funny...

[PATCH 4/6] ARM: smp: set thread_info->cpu to hardware CPU number for boot thread

[Russell King - ARM Linux]

On Mon, Aug 08, 2011 at 07:14:59PM +0100, Will Deacon wrote:
> On Mon, Aug 08, 2011 at 06:33:38PM +0100, Stephen Boyd wrote:
> > On 08/08/2011 10:10 AM, Will Deacon wrote:
> > >
> > >  
> > > +void __init smp_setup_processor_id(void)
> > > +{
> > > +	u32 mpidr;
> > > +
> > > +	/* Read the MPIDR to find the hardware ID of the current CPU. */
> > > +	asm("1:		mrc	p15, 0, %0, c0, c0, 5\n"
> > > +	    "		.pushsection \".alt.smp.init\", \"a\"\n"
> > > +	    "		.long	1b\n"
> > > +	    "		mov	%0, #0\n"
> > > +	    "		.popsection"
> > > +	    : "=r" (mpidr));
> > 
> > Would it be a good idea to put this into asm/cputype.h? I suppose the
> > smp alternatives part would need to be written in C.
> > 
> >     mpidr = is_smp() ? read_cpuid_mpidr() : 0;
> 
> Yes, that's much better. We used to have asm/smp_mpidr.h which did this, so I
> lifted the code from there but doing it in C is easier to read.
> 
> > >
> > > +
> > > +	current_thread_info()->cpu = mpidr & 0xff;
> > > +	printk("Booting Linux on CPU %d\n", current_thread_info()->cpu);
> > > +}
> > > +
> > 
> > Should there be a KERN_INFO there?
> 
> Can be. I just followed suit with secondary_start_kernel, but smp.c doesn't
> seem to be consistent anyway so I'll add the specifier.

Actually, it's probably much better to keep logical CPU0 as the boot CPU.
The hotplug code makes the assumption that the lowest online CPU number
is the boot CPU.

So unless we want even more pain, I suggest we just ensure logical CPU0
is the boot CPU.

We're already fairly clean on our interactions between CPU numbering and
the hardware CPU numbering - there's only a limited number of places where
the two interact.  Those are the GIC, IPI, secondary CPU bringup, and
hotplug code.  I suggest that we preserve the independence, and introduce
a mapping between logical CPU numbering and hardware CPU numbering.

[PATCH 4/6] ARM: smp: set thread_info->cpu to hardware CPU number for boot thread

[Will Deacon]

Hi Russell,

On Mon, Aug 08, 2011 at 09:02:56PM +0100, Russell King - ARM Linux wrote:
> On Mon, Aug 08, 2011 at 07:14:59PM +0100, Will Deacon wrote:
> > Can be. I just followed suit with secondary_start_kernel, but smp.c doesn't
> > seem to be consistent anyway so I'll add the specifier.
> 
> Actually, it's probably much better to keep logical CPU0 as the boot CPU.
> The hotplug code makes the assumption that the lowest online CPU number
> is the boot CPU.

Yes, you're right. I only tested this on a dual-core platform so I didn't
get a chance to play with hotplug (except to see that it failed, like I
expected). That assumption is also in the generic code so I guess it's
easier to leave it be.

> So unless we want even more pain, I suggest we just ensure logical CPU0
> is the boot CPU.

Right. Ensuring the logical CPU number isn't too hard, but we should aim to
support an arbitrary physical CPU number for the boot ID, even if most
platforms can't cater for that at the moment.

> We're already fairly clean on our interactions between CPU numbering and
> the hardware CPU numbering - there's only a limited number of places where
> the two interact.  Those are the GIC, IPI, secondary CPU bringup, and
> hotplug code.  I suggest that we preserve the independence, and introduce
> a mapping between logical CPU numbering and hardware CPU numbering.

This was my initial approach but then I thought I'd try and cheat my messing
with the logical numbering. I'll look at implementing the mapping and then
updating the GIC and friends to indirect their CPU number lookups through
that instead. I'll post it as its own series since it will be more than just
a simple hack now.

Stay tuned...

Cheers,

Will

[PATCH 2/6] ARM: realview: ensure visibility of writes during reset

[Rob Herring]

On 08/08/2011 12:10 PM, Will Deacon wrote:
> The various reset routines in mach-realview rely on an FPGA to
> power-cycle the board after writing some magic runes to memory-mapped
> registers.
> 
> This patch adds a dsb() following the writes, so that they become
> visible before we mdelay(1000) in the arch_reset code. Without this
> patch, the timeout would expire sporadically, causing the reset to fail.
> 
> Signed-off-by: Will Deacon <will.deacon@arm.com>
> ---
>  arch/arm/mach-realview/include/mach/system.h |    1 +
>  1 files changed, 1 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/arm/mach-realview/include/mach/system.h b/arch/arm/mach-realview/include/mach/system.h
> index a30f2e3..6657ff2 100644
> --- a/arch/arm/mach-realview/include/mach/system.h
> +++ b/arch/arm/mach-realview/include/mach/system.h
> @@ -44,6 +44,7 @@ static inline void arch_reset(char mode, const char *cmd)
>  	 */
>  	if (realview_reset)
>  		realview_reset(mode);
> +	dsb();

Wouldn't it be better to do this globally.

Rob

[PATCH 2/6] ARM: realview: ensure visibility of writes during reset

[Will Deacon]

Hi Rob,

On Mon, Aug 08, 2011 at 10:16:17PM +0100, Rob Herring wrote:
> On 08/08/2011 12:10 PM, Will Deacon wrote:
> > The various reset routines in mach-realview rely on an FPGA to
> > power-cycle the board after writing some magic runes to memory-mapped
> > registers.
> > 
> > This patch adds a dsb() following the writes, so that they become
> > visible before we mdelay(1000) in the arch_reset code. Without this
> > patch, the timeout would expire sporadically, causing the reset to fail.
> > 
> > Signed-off-by: Will Deacon <will.deacon@arm.com>
> > ---
> >  arch/arm/mach-realview/include/mach/system.h |    1 +
> >  1 files changed, 1 insertions(+), 0 deletions(-)
> > 
> > diff --git a/arch/arm/mach-realview/include/mach/system.h b/arch/arm/mach-realview/include/mach/system.h
> > index a30f2e3..6657ff2 100644
> > --- a/arch/arm/mach-realview/include/mach/system.h
> > +++ b/arch/arm/mach-realview/include/mach/system.h
> > @@ -44,6 +44,7 @@ static inline void arch_reset(char mode, const char *cmd)
> >  	 */
> >  	if (realview_reset)
> >  		realview_reset(mode);
> > +	dsb();
> 
> Wouldn't it be better to do this globally.

I'd rather leave it in the arch-specific code since otherwise it feels like
we're leaking the actual reset implementation into the caller. Plus it's not
entirely clear that there's a one-size-fits-all solution here.

Cheers,

Will

[PATCH 4/6] ARM: smp: set thread_info->cpu to hardware CPU number for boot thread

[Sergei Shtylyov]

Hello.

On 08-08-2011 21:10, Will Deacon wrote:

> On ARM, Linux assumes that the boot CPU has ID 0. If this ends up being
> out of sync with the hardware CPU number, we will configure the GIC
> incorrectly and route interrupts to the CPU with hardware ID 0.

> This patch implements smp_setup_processor_id for ARM, using the MPIDR to
> set the CPU of the boot thread.

> Signed-off-by: Will Deacon<will.deacon@arm.com>
> ---
>   arch/arm/kernel/smp.c |   16 ++++++++++++++++
>   1 files changed, 16 insertions(+), 0 deletions(-)

> diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
> index d88ff02..8e60a4f 100644
> --- a/arch/arm/kernel/smp.c
> +++ b/arch/arm/kernel/smp.c
> @@ -259,6 +259,22 @@ void __ref cpu_die(void)
>   }
>   #endif /* CONFIG_HOTPLUG_CPU */
>
> +void __init smp_setup_processor_id(void)
> +{
> +	u32 mpidr;
> +
> +	/* Read the MPIDR to find the hardware ID of the current CPU. */
> +	asm("1:		mrc	p15, 0, %0, c0, c0, 5\n"
> +	    "		.pushsection \".alt.smp.init\", \"a\"\n"
> +	    "		.long	1b\n"
> +	    "		mov	%0, #0\n"
> +	    "		.popsection"
> +	    : "=r" (mpidr));
> +
> +	current_thread_info()->cpu = mpidr&  0xff;
> +	printk("Booting Linux on CPU %d\n", current_thread_info()->cpu);

    printk() should have the KERN_* logging facility.

WBR, Sergei

[PATCH 4/6] ARM: smp: set thread_info->cpu to hardware CPU number for boot thread

[Will Deacon]

On Tue, Aug 09, 2011 at 12:48:05PM +0100, Sergei Shtylyov wrote:
> Hello.
> 
> On 08-08-2011 21:10, Will Deacon wrote:
> 
> > On ARM, Linux assumes that the boot CPU has ID 0. If this ends up being
> > out of sync with the hardware CPU number, we will configure the GIC
> > incorrectly and route interrupts to the CPU with hardware ID 0.
> 
> > This patch implements smp_setup_processor_id for ARM, using the MPIDR to
> > set the CPU of the boot thread.
> 
> > Signed-off-by: Will Deacon<will.deacon@arm.com>
> > ---
> >   arch/arm/kernel/smp.c |   16 ++++++++++++++++
> >   1 files changed, 16 insertions(+), 0 deletions(-)
> 
> > diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
> > index d88ff02..8e60a4f 100644
> > --- a/arch/arm/kernel/smp.c
> > +++ b/arch/arm/kernel/smp.c
> > @@ -259,6 +259,22 @@ void __ref cpu_die(void)
> >   }
> >   #endif /* CONFIG_HOTPLUG_CPU */
> >
> > +void __init smp_setup_processor_id(void)
> > +{
> > +	u32 mpidr;
> > +
> > +	/* Read the MPIDR to find the hardware ID of the current CPU. */
> > +	asm("1:		mrc	p15, 0, %0, c0, c0, 5\n"
> > +	    "		.pushsection \".alt.smp.init\", \"a\"\n"
> > +	    "		.long	1b\n"
> > +	    "		mov	%0, #0\n"
> > +	    "		.popsection"
> > +	    : "=r" (mpidr));
> > +
> > +	current_thread_info()->cpu = mpidr&  0xff;
> > +	printk("Booting Linux on CPU %d\n", current_thread_info()->cpu);
> 
>     printk() should have the KERN_* logging facility.

There's an echo around here :) This patch is pretty much dead anyway after
the discussion with Russell. I'll post some other guys soon.

Will