* [PATCH] powerpc/pasemi: Defer Nemo IRQ initialization
@ 2026-10-24 7:55 chzigotzky
2026-10-28 3:53 ` Christian Zigotzky
2026-11-02 3:34 ` Ritesh Harjani
0 siblings, 2 replies; 5+ messages in thread
From: chzigotzky @ 2026-10-24 7:55 UTC (permalink / raw)
To: maddy, mpe
Cc: npiggin, linuxppc-dev, Christian Zigotzky A-EON Open Source,
Darren Stevens, Christian Zigotzky
From: Christian Zigotzky A-EON Open Source <info@xenosoft.de>
Since pas_pci_init() is now called later during boot, the i8259
initialization in pas_init_IRQ() happens too early and accesses
registers that are not yet mapped, preventing the board from booting.
Move the Nemo-specific i8259 initialization to pas_add_bridge(),
after the ISA bridge has been discovered.
Suggested-by: Darren Stevens <darren@stevens-zone.net>
Tested-by: Christian Zigotzky <chzigotzky@xenosoft.de>
Signed-off-by: Christian Zigotzky A-EON Open Source <info@xenosoft.de>
---
arch/powerpc/platforms/pasemi/pasemi.h | 6 ++++++
arch/powerpc/platforms/pasemi/pci.c | 5 +++++
arch/powerpc/platforms/pasemi/setup.c | 12 ++++--------
3 files changed, 15 insertions(+), 8 deletions(-)
diff --git a/arch/powerpc/platforms/pasemi/pasemi.h b/arch/powerpc/platforms/pasemi/pasemi.h
index 6f6743b8e48d..01bcfa258625 100644
--- a/arch/powerpc/platforms/pasemi/pasemi.h
+++ b/arch/powerpc/platforms/pasemi/pasemi.h
@@ -7,6 +7,12 @@ extern void pas_pci_init(void);
struct pci_dev;
extern void pas_pci_dma_dev_setup(struct pci_dev *dev);
+#ifdef CONFIG_PPC_PASEMI_NEMO
+void __init nemo_init_IRQ(void);
+#else
+static inline void __init nemo_init_IRQ(void) { }
+#endif
+
void __iomem *__init pasemi_pci_getcfgaddr(struct pci_dev *dev, int offset);
extern void __init pasemi_map_registers(void);
diff --git a/arch/powerpc/platforms/pasemi/pci.c b/arch/powerpc/platforms/pasemi/pci.c
index 2df955274652..fb53782da7ec 100644
--- a/arch/powerpc/platforms/pasemi/pci.c
+++ b/arch/powerpc/platforms/pasemi/pci.c
@@ -265,6 +265,11 @@ static int __init pas_add_bridge(struct device_node *dev)
*/
isa_bridge_find_early(hose);
+ /*
+ * ISA bridge is now active, add the i8259 cascade (if needed)
+ */
+ nemo_init_IRQ();
+
return 0;
}
diff --git a/arch/powerpc/platforms/pasemi/setup.c b/arch/powerpc/platforms/pasemi/setup.c
index 45792ecd5dfd..7a961f2a228f 100644
--- a/arch/powerpc/platforms/pasemi/setup.c
+++ b/arch/powerpc/platforms/pasemi/setup.c
@@ -216,10 +216,12 @@ static void sb600_8259_cascade(struct irq_desc *desc)
chip->irq_eoi(&desc->irq_data);
}
-static void __init nemo_init_IRQ(struct mpic *mpic)
+void __init nemo_init_IRQ(void)
{
struct device_node *np;
int gpio_virq;
+ struct mpic *mpic;
+
/* Connect the SB600's legacy i8259 controller */
np = of_find_node_by_path("/pxp@0,e0000000");
i8259_init(np, 0);
@@ -230,14 +232,10 @@ static void __init nemo_init_IRQ(struct mpic *mpic)
irq_set_chained_handler(gpio_virq, sb600_8259_cascade);
mpic_unmask_irq(irq_get_irq_data(gpio_virq));
+ mpic = irq_get_chip_data(gpio_virq);
irq_set_default_domain(mpic->irqhost);
}
-#else
-
-static inline void nemo_init_IRQ(struct mpic *mpic)
-{
-}
#endif
static __init void pas_init_IRQ(void)
@@ -300,8 +298,6 @@ static __init void pas_init_IRQ(void)
mpic_unmask_irq(irq_get_irq_data(nmi_virq));
}
- nemo_init_IRQ(mpic);
-
of_node_put(mpic_node);
of_node_put(root);
}
--
2.43.0
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH] powerpc/pasemi: Defer Nemo IRQ initialization
2026-10-24 7:55 [PATCH] powerpc/pasemi: Defer Nemo IRQ initialization chzigotzky
@ 2026-10-28 3:53 ` Christian Zigotzky
2026-11-02 3:34 ` Ritesh Harjani
1 sibling, 0 replies; 5+ messages in thread
From: Christian Zigotzky @ 2026-10-28 3:53 UTC (permalink / raw)
To: maddy, mpe, linuxppc-dev
Cc: npiggin, Christian Zigotzky A-EON Open Source, Darren Stevens,
R.T.Dickinson, mad skateman, Damien Stewart, oe-kbuild-all,
Philip Li
Hi all,
I have created a new patch. I hope it is OK. It works without any problems.
Thanks,
Christian
On 24/10/26 09:55, chzigotzky@xenosoft.de wrote:
> From: Christian Zigotzky A-EON Open Source <info@xenosoft.de>
>
> Since pas_pci_init() is now called later during boot, the i8259
> initialization in pas_init_IRQ() happens too early and accesses
> registers that are not yet mapped, preventing the board from booting.
>
> Move the Nemo-specific i8259 initialization to pas_add_bridge(),
> after the ISA bridge has been discovered.
>
> Suggested-by: Darren Stevens <darren@stevens-zone.net>
> Tested-by: Christian Zigotzky <chzigotzky@xenosoft.de>
> Signed-off-by: Christian Zigotzky A-EON Open Source <info@xenosoft.de>
> ---
> arch/powerpc/platforms/pasemi/pasemi.h | 6 ++++++
> arch/powerpc/platforms/pasemi/pci.c | 5 +++++
> arch/powerpc/platforms/pasemi/setup.c | 12 ++++--------
> 3 files changed, 15 insertions(+), 8 deletions(-)
>
> diff --git a/arch/powerpc/platforms/pasemi/pasemi.h b/arch/powerpc/platforms/pasemi/pasemi.h
> index 6f6743b8e48d..01bcfa258625 100644
> --- a/arch/powerpc/platforms/pasemi/pasemi.h
> +++ b/arch/powerpc/platforms/pasemi/pasemi.h
> @@ -7,6 +7,12 @@ extern void pas_pci_init(void);
> struct pci_dev;
> extern void pas_pci_dma_dev_setup(struct pci_dev *dev);
>
> +#ifdef CONFIG_PPC_PASEMI_NEMO
> +void __init nemo_init_IRQ(void);
> +#else
> +static inline void __init nemo_init_IRQ(void) { }
> +#endif
> +
> void __iomem *__init pasemi_pci_getcfgaddr(struct pci_dev *dev, int offset);
>
> extern void __init pasemi_map_registers(void);
> diff --git a/arch/powerpc/platforms/pasemi/pci.c b/arch/powerpc/platforms/pasemi/pci.c
> index 2df955274652..fb53782da7ec 100644
> --- a/arch/powerpc/platforms/pasemi/pci.c
> +++ b/arch/powerpc/platforms/pasemi/pci.c
> @@ -265,6 +265,11 @@ static int __init pas_add_bridge(struct device_node *dev)
> */
> isa_bridge_find_early(hose);
>
> + /*
> + * ISA bridge is now active, add the i8259 cascade (if needed)
> + */
> + nemo_init_IRQ();
> +
> return 0;
> }
>
> diff --git a/arch/powerpc/platforms/pasemi/setup.c b/arch/powerpc/platforms/pasemi/setup.c
> index 45792ecd5dfd..7a961f2a228f 100644
> --- a/arch/powerpc/platforms/pasemi/setup.c
> +++ b/arch/powerpc/platforms/pasemi/setup.c
> @@ -216,10 +216,12 @@ static void sb600_8259_cascade(struct irq_desc *desc)
> chip->irq_eoi(&desc->irq_data);
> }
>
> -static void __init nemo_init_IRQ(struct mpic *mpic)
> +void __init nemo_init_IRQ(void)
> {
> struct device_node *np;
> int gpio_virq;
> + struct mpic *mpic;
> +
> /* Connect the SB600's legacy i8259 controller */
> np = of_find_node_by_path("/pxp@0,e0000000");
> i8259_init(np, 0);
> @@ -230,14 +232,10 @@ static void __init nemo_init_IRQ(struct mpic *mpic)
> irq_set_chained_handler(gpio_virq, sb600_8259_cascade);
> mpic_unmask_irq(irq_get_irq_data(gpio_virq));
>
> + mpic = irq_get_chip_data(gpio_virq);
> irq_set_default_domain(mpic->irqhost);
> }
>
> -#else
> -
> -static inline void nemo_init_IRQ(struct mpic *mpic)
> -{
> -}
> #endif
>
> static __init void pas_init_IRQ(void)
> @@ -300,8 +298,6 @@ static __init void pas_init_IRQ(void)
> mpic_unmask_irq(irq_get_irq_data(nmi_virq));
> }
>
> - nemo_init_IRQ(mpic);
> -
> of_node_put(mpic_node);
> of_node_put(root);
> }
--
Sent with BrassMonkey 35.0.2 (https://github.com/chzigotzky/Web-Browsers-and-Suites-for-Linux-PPC/releases/tag/BrassMonkey_35.0.2)
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH] powerpc/pasemi: Defer Nemo IRQ initialization
2026-10-30 16:21 ` Ritesh Harjani
@ 2026-11-01 11:35 ` Christian Zigotzky
0 siblings, 0 replies; 5+ messages in thread
From: Christian Zigotzky @ 2026-11-01 11:35 UTC (permalink / raw)
To: Ritesh Harjani (IBM), Shrikanth Hegde, Narayana Murty N, maddy,
linuxppc-dev
Cc: mpe, npiggin, christophe.leroy, linux-kernel, msuchanek, harshpb,
gautam, amachhiw, venkat88, R.T.Dickinson, mad skateman,
Damien Stewart, Christian Zigotzky, Darren Stevens
On 10/30/2026 05:21 PM, Ritesh Harjani (IBM) wrote:
> Let's ask Christian directly :)
> @Christian - Once we have v2, would you kindly help us test that
> please?
>
> We think the other approach which Narayana suggested might be a better
> fix for this and it can avoid preempt_enable/disable() dance. However,
> looks like we may not have the board where we can reproduce this.
>
>
> -ritesh
>
Hi all,
Is it possible to add the following patch to the kernel?
Link:
https://lists.ozlabs.org/pipermail/linuxppc-dev/2026-October/305189.html
It is more important for us because the Nemo board can't boot without
this patch.
Thanks,
Christian
--
Sent with BrassMonkey 35.0.2 (https://github.com/chzigotzky/Web-Browsers-and-Suites-for-Linux-PPC/releases/tag/BrassMonkey_35.0.2)
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] powerpc/pasemi: Defer Nemo IRQ initialization
2026-10-24 7:55 [PATCH] powerpc/pasemi: Defer Nemo IRQ initialization chzigotzky
2026-10-28 3:53 ` Christian Zigotzky
@ 2026-11-02 3:34 ` Ritesh Harjani
2026-11-02 5:20 ` Christian Zigotzky
1 sibling, 1 reply; 5+ messages in thread
From: Ritesh Harjani @ 2026-11-02 3:34 UTC (permalink / raw)
To: chzigotzky, maddy, mpe
Cc: npiggin, linuxppc-dev, Christian Zigotzky A-EON Open Source,
Darren Stevens, Christian Zigotzky
chzigotzky@xenosoft.de writes:
> From: Christian Zigotzky A-EON Open Source <info@xenosoft.de>
>
> Since pas_pci_init() is now called later during boot, the i8259
> initialization in pas_init_IRQ() happens too early and accesses
> registers that are not yet mapped, preventing the board from booting.
>
> Move the Nemo-specific i8259 initialization to pas_add_bridge(),
> after the ISA bridge has been discovered.
That make sense to me. The patch looks good. However, shouldn't we also
add Fixes tag and Cc: stable tag - so that this gets backported to older
stable kernels.
Fixes: c144bc719234 ("powerpc/pasemi: Move PHB discovery")
Cc: stable@vger.kernel.org
I think the fixes tag should be above - but feel free to correct that.
Otherwise looks good to me. Feel free to add:
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
>
> Suggested-by: Darren Stevens <darren@stevens-zone.net>
> Tested-by: Christian Zigotzky <chzigotzky@xenosoft.de>
> Signed-off-by: Christian Zigotzky A-EON Open Source <info@xenosoft.de>
> ---
> arch/powerpc/platforms/pasemi/pasemi.h | 6 ++++++
> arch/powerpc/platforms/pasemi/pci.c | 5 +++++
> arch/powerpc/platforms/pasemi/setup.c | 12 ++++--------
> 3 files changed, 15 insertions(+), 8 deletions(-)
>
> diff --git a/arch/powerpc/platforms/pasemi/pasemi.h b/arch/powerpc/platforms/pasemi/pasemi.h
> index 6f6743b8e48d..01bcfa258625 100644
> --- a/arch/powerpc/platforms/pasemi/pasemi.h
> +++ b/arch/powerpc/platforms/pasemi/pasemi.h
> @@ -7,6 +7,12 @@ extern void pas_pci_init(void);
> struct pci_dev;
> extern void pas_pci_dma_dev_setup(struct pci_dev *dev);
>
> +#ifdef CONFIG_PPC_PASEMI_NEMO
> +void __init nemo_init_IRQ(void);
> +#else
> +static inline void __init nemo_init_IRQ(void) { }
> +#endif
> +
> void __iomem *__init pasemi_pci_getcfgaddr(struct pci_dev *dev, int offset);
>
> extern void __init pasemi_map_registers(void);
> diff --git a/arch/powerpc/platforms/pasemi/pci.c b/arch/powerpc/platforms/pasemi/pci.c
> index 2df955274652..fb53782da7ec 100644
> --- a/arch/powerpc/platforms/pasemi/pci.c
> +++ b/arch/powerpc/platforms/pasemi/pci.c
> @@ -265,6 +265,11 @@ static int __init pas_add_bridge(struct device_node *dev)
> */
> isa_bridge_find_early(hose);
>
> + /*
> + * ISA bridge is now active, add the i8259 cascade (if needed)
> + */
> + nemo_init_IRQ();
> +
> return 0;
> }
>
> diff --git a/arch/powerpc/platforms/pasemi/setup.c b/arch/powerpc/platforms/pasemi/setup.c
> index 45792ecd5dfd..7a961f2a228f 100644
> --- a/arch/powerpc/platforms/pasemi/setup.c
> +++ b/arch/powerpc/platforms/pasemi/setup.c
> @@ -216,10 +216,12 @@ static void sb600_8259_cascade(struct irq_desc *desc)
> chip->irq_eoi(&desc->irq_data);
> }
>
> -static void __init nemo_init_IRQ(struct mpic *mpic)
> +void __init nemo_init_IRQ(void)
> {
> struct device_node *np;
> int gpio_virq;
> + struct mpic *mpic;
> +
> /* Connect the SB600's legacy i8259 controller */
> np = of_find_node_by_path("/pxp@0,e0000000");
> i8259_init(np, 0);
> @@ -230,14 +232,10 @@ static void __init nemo_init_IRQ(struct mpic *mpic)
> irq_set_chained_handler(gpio_virq, sb600_8259_cascade);
> mpic_unmask_irq(irq_get_irq_data(gpio_virq));
>
> + mpic = irq_get_chip_data(gpio_virq);
> irq_set_default_domain(mpic->irqhost);
> }
>
> -#else
> -
> -static inline void nemo_init_IRQ(struct mpic *mpic)
> -{
> -}
> #endif
>
> static __init void pas_init_IRQ(void)
> @@ -300,8 +298,6 @@ static __init void pas_init_IRQ(void)
> mpic_unmask_irq(irq_get_irq_data(nmi_virq));
> }
>
> - nemo_init_IRQ(mpic);
> -
> of_node_put(mpic_node);
> of_node_put(root);
> }
> --
> 2.43.0
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] powerpc/pasemi: Defer Nemo IRQ initialization
2026-11-02 3:34 ` Ritesh Harjani
@ 2026-11-02 5:20 ` Christian Zigotzky
0 siblings, 0 replies; 5+ messages in thread
From: Christian Zigotzky @ 2026-11-02 5:20 UTC (permalink / raw)
To: Ritesh Harjani (IBM), maddy, mpe
Cc: npiggin, linuxppc-dev, Christian Zigotzky A-EON Open Source,
Darren Stevens, R.T.Dickinson, Damien Stewart, mad skateman
On 11/02/2026 04:34 AM, Ritesh Harjani (IBM) wrote:
> chzigotzky@xenosoft.de writes:
>
>> From: Christian Zigotzky A-EON Open Source <info@xenosoft.de>
>>
>> Since pas_pci_init() is now called later during boot, the i8259
>> initialization in pas_init_IRQ() happens too early and accesses
>> registers that are not yet mapped, preventing the board from booting.
>>
>> Move the Nemo-specific i8259 initialization to pas_add_bridge(),
>> after the ISA bridge has been discovered.
>
> That make sense to me. The patch looks good. However, shouldn't we also
> add Fixes tag and Cc: stable tag - so that this gets backported to older
> stable kernels.
>
>
> Fixes: c144bc719234 ("powerpc/pasemi: Move PHB discovery")
> Cc: stable@vger.kernel.org
>
> I think the fixes tag should be above - but feel free to correct that.
>
> Otherwise looks good to me. Feel free to add:
> Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
>
Great! Just for info. I don't need this patch for the stable long-term
kernel 5.10 but it is at least necessary for the stable long-term
kernels 6.12 [1] and 6.18.
- Christian
[1]
https://raw.githubusercontent.com/chzigotzky/kernels/refs/heads/6_12/patches/X1000/pas_pci_init_v6.patch
>> Suggested-by: Darren Stevens <darren@stevens-zone.net>
>> Tested-by: Christian Zigotzky <chzigotzky@xenosoft.de>
>> Signed-off-by: Christian Zigotzky A-EON Open Source <info@xenosoft.de>
>> ---
>> arch/powerpc/platforms/pasemi/pasemi.h | 6 ++++++
>> arch/powerpc/platforms/pasemi/pci.c | 5 +++++
>> arch/powerpc/platforms/pasemi/setup.c | 12 ++++--------
>> 3 files changed, 15 insertions(+), 8 deletions(-)
>>
>> diff --git a/arch/powerpc/platforms/pasemi/pasemi.h b/arch/powerpc/platforms/pasemi/pasemi.h
>> index 6f6743b8e48d..01bcfa258625 100644
>> --- a/arch/powerpc/platforms/pasemi/pasemi.h
>> +++ b/arch/powerpc/platforms/pasemi/pasemi.h
>> @@ -7,6 +7,12 @@ extern void pas_pci_init(void);
>> struct pci_dev;
>> extern void pas_pci_dma_dev_setup(struct pci_dev *dev);
>>
>> +#ifdef CONFIG_PPC_PASEMI_NEMO
>> +void __init nemo_init_IRQ(void);
>> +#else
>> +static inline void __init nemo_init_IRQ(void) { }
>> +#endif
>> +
>> void __iomem *__init pasemi_pci_getcfgaddr(struct pci_dev *dev, int offset);
>>
>> extern void __init pasemi_map_registers(void);
>> diff --git a/arch/powerpc/platforms/pasemi/pci.c b/arch/powerpc/platforms/pasemi/pci.c
>> index 2df955274652..fb53782da7ec 100644
>> --- a/arch/powerpc/platforms/pasemi/pci.c
>> +++ b/arch/powerpc/platforms/pasemi/pci.c
>> @@ -265,6 +265,11 @@ static int __init pas_add_bridge(struct device_node *dev)
>> */
>> isa_bridge_find_early(hose);
>>
>> + /*
>> + * ISA bridge is now active, add the i8259 cascade (if needed)
>> + */
>> + nemo_init_IRQ();
>> +
>> return 0;
>> }
>>
>> diff --git a/arch/powerpc/platforms/pasemi/setup.c b/arch/powerpc/platforms/pasemi/setup.c
>> index 45792ecd5dfd..7a961f2a228f 100644
>> --- a/arch/powerpc/platforms/pasemi/setup.c
>> +++ b/arch/powerpc/platforms/pasemi/setup.c
>> @@ -216,10 +216,12 @@ static void sb600_8259_cascade(struct irq_desc *desc)
>> chip->irq_eoi(&desc->irq_data);
>> }
>>
>> -static void __init nemo_init_IRQ(struct mpic *mpic)
>> +void __init nemo_init_IRQ(void)
>> {
>> struct device_node *np;
>> int gpio_virq;
>> + struct mpic *mpic;
>> +
>> /* Connect the SB600's legacy i8259 controller */
>> np = of_find_node_by_path("/pxp@0,e0000000");
>> i8259_init(np, 0);
>> @@ -230,14 +232,10 @@ static void __init nemo_init_IRQ(struct mpic *mpic)
>> irq_set_chained_handler(gpio_virq, sb600_8259_cascade);
>> mpic_unmask_irq(irq_get_irq_data(gpio_virq));
>>
>> + mpic = irq_get_chip_data(gpio_virq);
>> irq_set_default_domain(mpic->irqhost);
>> }
>>
>> -#else
>> -
>> -static inline void nemo_init_IRQ(struct mpic *mpic)
>> -{
>> -}
>> #endif
>>
>> static __init void pas_init_IRQ(void)
>> @@ -300,8 +298,6 @@ static __init void pas_init_IRQ(void)
>> mpic_unmask_irq(irq_get_irq_data(nmi_virq));
>> }
>>
>> - nemo_init_IRQ(mpic);
>> -
>> of_node_put(mpic_node);
>> of_node_put(root);
>> }
>> --
>> 2.43.0
--
Sent with BrassMonkey 35.0.2 (https://github.com/chzigotzky/Web-Browsers-and-Suites-for-Linux-PPC/releases/tag/BrassMonkey_35.0.2)
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2026-11-02 5:20 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-10-24 7:55 [PATCH] powerpc/pasemi: Defer Nemo IRQ initialization chzigotzky
2026-10-28 3:53 ` Christian Zigotzky
2026-11-02 3:34 ` Ritesh Harjani
2026-11-02 5:20 ` Christian Zigotzky
-- strict thread matches above, loose matches on Subject: below --
2026-09-28 11:04 [PATCH 0/2] KVM: PPC: BookE: Fix boot hang on preemptible kernels Shrikanth Hegde
2026-09-28 11:04 ` [PATCH 1/2] KVM: PPC: BookE: Disable preemption before loading guest FP and Altivec Shrikanth Hegde
2026-10-01 11:26 ` Narayana Murty N
2026-10-01 11:53 ` Shrikanth Hegde
2026-10-30 16:21 ` Ritesh Harjani
2026-11-01 11:35 ` [PATCH] powerpc/pasemi: Defer Nemo IRQ initialization Christian Zigotzky
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