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Date: Thu, 20 Nov 2014 12:26:10 +0800
From: Jiang Liu <jiang.liu@...ux.intel.com>
To: Marc Zyngier <marc.zyngier@....com>,
Yingjoe Chen <yingjoe.chen@...iatek.com>
CC: Thomas Gleixner <tglx@...utronix.de>,
Mark Rutland <Mark.Rutland@....com>,
Boris BREZILLON <boris.brezillon@...e-electrons.com>,
Russell King <linux@....linux.org.uk>,
Jason Cooper <jason@...edaemon.net>,
Pawel Moll <Pawel.Moll@....com>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"hc.yen@...iatek.com" <hc.yen@...iatek.com>,
"srv_heupstream@...iatek.com" <srv_heupstream@...iatek.com>,
"yh.chen@...iatek.com" <yh.chen@...iatek.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"grant.likely@...aro.org" <grant.likely@...aro.org>,
Yijing Wang <wangyijing@...wei.com>,
Rob Herring <robh+dt@...nel.org>,
"nathan.chung@...iatek.com" <nathan.chung@...iatek.com>,
"yingjoe.chen@...il.com" <yingjoe.chen@...il.com>,
Matthias Brugger <matthias.bgg@...il.com>,
"eddie.huang@...iatek.com" <eddie.huang@...iatek.com>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Sascha Hauer <kernel@...gutronix.de>,
"linux- arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v7 1/4] irqchip: gic: Support hierarchy irq domain.
On 2014/11/20 1:18, Marc Zyngier wrote:
> Hi Yingjoe,
>
> On Wed, Nov 19 2014 at 2:14:08 pm GMT, Yingjoe Chen <yingjoe.chen@...iatek.com> wrote:
>> Add support to use gic as a parent for stacked irq domain.
>>
>> Signed-off-by: Yingjoe Chen <yingjoe.chen@...iatek.com>
>> ---
>> drivers/irqchip/Kconfig | 1 +
>> drivers/irqchip/irq-gic.c | 78 ++++++++++++++++++++++++++++++++---------------
>> 2 files changed, 55 insertions(+), 24 deletions(-)
>>
>> diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
>> index b21f12f..7f34138 100644
>> --- a/drivers/irqchip/Kconfig
>> +++ b/drivers/irqchip/Kconfig
>> @@ -5,6 +5,7 @@ config IRQCHIP
>> config ARM_GIC
>> bool
>> select IRQ_DOMAIN
>> + select IRQ_DOMAIN_HIERARCHY
>> select MULTI_IRQ_HANDLER
>>
>> config GIC_NON_BANKED
>> diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c
>> index 38493ff..464dd53 100644
>> --- a/drivers/irqchip/irq-gic.c
>> +++ b/drivers/irqchip/irq-gic.c
>> @@ -788,17 +788,16 @@ static int gic_irq_domain_map(struct irq_domain *d, unsigned int irq,
>> {
>> if (hw < 32) {
>> irq_set_percpu_devid(irq);
>> - irq_set_chip_and_handler(irq, &gic_chip,
>> - handle_percpu_devid_irq);
>> + irq_domain_set_info(d, irq, hw, &gic_chip, d->host_data,
>> + handle_percpu_devid_irq, NULL, NULL);
>> set_irq_flags(irq, IRQF_VALID | IRQF_NOAUTOEN);
>> } else {
>> - irq_set_chip_and_handler(irq, &gic_chip,
>> - handle_fasteoi_irq);
>> + irq_domain_set_info(d, irq, hw, &gic_chip, d->host_data,
>> + handle_fasteoi_irq, NULL, NULL);
>> set_irq_flags(irq, IRQF_VALID | IRQF_PROBE);
>>
>> gic_routable_irq_domain_ops->map(d, irq, hw);
>> }
>> - irq_set_chip_data(irq, d->host_data);
>> return 0;
>> }
>>
>> @@ -858,6 +857,31 @@ static struct notifier_block gic_cpu_notifier = {
>> };
>> #endif
>>
>> +static int gic_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
>> + unsigned int nr_irqs, void *arg)
>> +{
>> + int i, ret;
>> + irq_hw_number_t hwirq;
>> + unsigned int type = IRQ_TYPE_NONE;
>> + struct of_phandle_args *irq_data = arg;
>> +
>> + ret = gic_irq_domain_xlate(domain, irq_data->np, irq_data->args,
>> + irq_data->args_count, &hwirq, &type);
>> + if (ret)
>> + return ret;
>> +
>> + for (i = 0; i < nr_irqs; i++)
>> + gic_irq_domain_map(domain, virq+i, hwirq+i);
>
> nit: spacing around '+'.
>
>> +
>> + return 0;
>> +}
>> +
>> +static const struct irq_domain_ops gic_irq_domain_hierarchy_ops = {
>> + .xlate = gic_irq_domain_xlate,
>> + .alloc = gic_irq_domain_alloc,
>> + .free = irq_domain_free_irqs_top,
>
> I'm convinced that irq_domain_free_irqs_top is the wrong function to
> call here, because you're calling it from the bottom, not the top-level
> (it has no parent).
>
> I cannot verify this with your code as I don't a working platform with
> GICv2m, but if I enable something similar on GICv3, it dies a very
> painful way:
>
> Unable to handle kernel NULL pointer dereference at virtual address 00000018
> pgd = ffffffc03d059000
> [00000018] *pgd=0000000081356003, *pud=0000000081356003, *pmd=0000000000000000
> Internal error: Oops: 96000006 [#1] SMP
> Modules linked in:
> CPU: 4 PID: 1052 Comm: sh Not tainted 3.18.0-rc4+ #3311
> task: ffffffc03e320000 ti: ffffffc001390000 task.ti: ffffffc001390000
> PC is at irq_domain_free_irqs_recursive+0x1c/0x80
> LR is at irq_domain_free_irqs_common+0x88/0x9c
> pc : [<ffffffc0000ed790>] lr : [<ffffffc0000ede20>] pstate: 60000145
> [...]
> [<ffffffc0000ed790>] irq_domain_free_irqs_recursive+0x1c/0x80
> [<ffffffc0000ede1c>] irq_domain_free_irqs_common+0x84/0x9c
> [<ffffffc0000ede98>] irq_domain_free_irqs_top+0x64/0x7c <-- gic_domain.free()
> [<ffffffc0000ed798>] irq_domain_free_irqs_recursive+0x24/0x80
> [<ffffffc0000ee468>] irq_domain_free_irqs_parent+0x14/0x20
> [<ffffffc0003500b8>] its_irq_domain_free+0xc8/0x250
> [<ffffffc0000ed798>] irq_domain_free_irqs_recursive+0x24/0x80
> [<ffffffc0000ede1c>] irq_domain_free_irqs_common+0x84/0x9c
> [<ffffffc0000ede98>] irq_domain_free_irqs_top+0x64/0x7c
> [<ffffffc0000ef518>] msi_domain_free+0x70/0x88
> [<ffffffc0000ed798>] irq_domain_free_irqs_recursive+0x24/0x80
> [<ffffffc0000ee3ac>] irq_domain_free_irqs+0x108/0x17c
> [<ffffffc0000efb68>] msi_domain_free_irqs+0x28/0x4c
> [<ffffffc000369cac>] free_msi_irqs+0xb4/0x1c0
> [<ffffffc00036adec>] pci_disable_msix+0x3c/0x4c
> [...]
>
> and I cannot see how this could work on the standard GIC either.
>
> Thomas, Jiang: could you please confirm or infirm my suspicions? My
> understanding is that irq_domain_free_irqs_top can only be called from
> the top-level domain.
Hi Marc,
It indicates that irq_domain_free_irqs_top() is not a good name.
We have:
1) irq_domain_set_hwirq_and_chip() to set irq_chip and chip_data
2) irq_domain_set_info() to set irq_chip, chip_data, flow_handler and
handler_data;
3) irq_domain_reset_irq_data() resets irq_chip and chip_data.
4) irq_domain_free_irqs_common() resets irq_chip, chip_data and calls
parent domain's domain_ops.free() callback.
5) irq_domain_free_irqs_top() resets irq_chip, chip_data, flow handler,
handler_data and call parent domain's domain_ops.free() callback.
So there two possible improvements here:
1) Rename irq_domain_free_irqs_top() with better name, any suggestions?
It's named as is because it's always called by the outer-most
irqdomains on x86.
2) Change irq_domain_free_irqs_common() and irq_domain_free_irqs_top()
to call parent domain's domain_ops.free() callback only if parent
exists. By this way, they could be used for inner-most irqdomains.
If OK, I will respin a version 4 patch set based on tip/irq/irqdomain.
Thoughts?
Regards!
Gerry
>
>> +};
>> +
>> static const struct irq_domain_ops gic_irq_domain_ops = {
>> .map = gic_irq_domain_map,
>> .unmap = gic_irq_domain_unmap,
>> @@ -948,18 +972,6 @@ void __init gic_init_bases(unsigned int gic_nr, int irq_start,
>> gic_cpu_map[i] = 0xff;
>>
>> /*
>> - * For primary GICs, skip over SGIs.
>> - * For secondary GICs, skip over PPIs, too.
>> - */
>> - if (gic_nr == 0 && (irq_start & 31) > 0) {
>> - hwirq_base = 16;
>> - if (irq_start != -1)
>> - irq_start = (irq_start & ~31) + 16;
>> - } else {
>> - hwirq_base = 32;
>> - }
>> -
>> - /*
>> * Find out how many interrupts are supported.
>> * The GIC only supports up to 1020 interrupt sources.
>> */
>> @@ -969,10 +981,32 @@ void __init gic_init_bases(unsigned int gic_nr, int irq_start,
>> gic_irqs = 1020;
>> gic->gic_irqs = gic_irqs;
>>
>> - gic_irqs -= hwirq_base; /* calculate # of irqs to allocate */
>> + if (node) { /* DT case */
>> + const struct irq_domain_ops *ops =
>> + &gic_irq_domain_hierarchy_ops;
>
> nit: please put this on the same line, even if it is longer than 80
> characters.
>
>> +
>> + if (!of_property_read_u32(node, "arm,routable-irqs",
>> + &nr_routable_irqs)) {
>> + ops = &gic_irq_domain_ops;
>> + gic_irqs = nr_routable_irqs;
>> + }
>> +
>> + gic->domain = irq_domain_add_linear(node, gic_irqs, ops, gic);
>> + } else { /* Non-DT case */
>> + /*
>> + * For primary GICs, skip over SGIs.
>> + * For secondary GICs, skip over PPIs, too.
>> + */
>> + if (gic_nr == 0 && (irq_start & 31) > 0) {
>> + hwirq_base = 16;
>> + if (irq_start != -1)
>> + irq_start = (irq_start & ~31) + 16;
>> + } else {
>> + hwirq_base = 32;
>> + }
>> +
>> + gic_irqs -= hwirq_base; /* calculate # of irqs to allocate */
>>
>> - if (of_property_read_u32(node, "arm,routable-irqs",
>> - &nr_routable_irqs)) {
>> irq_base = irq_alloc_descs(irq_start, 16, gic_irqs,
>> numa_node_id());
>> if (IS_ERR_VALUE(irq_base)) {
>> @@ -983,10 +1017,6 @@ void __init gic_init_bases(unsigned int gic_nr, int irq_start,
>>
>> gic->domain = irq_domain_add_legacy(node, gic_irqs, irq_base,
>> hwirq_base, &gic_irq_domain_ops, gic);
>> - } else {
>> - gic->domain = irq_domain_add_linear(node, nr_routable_irqs,
>> - &gic_irq_domain_ops,
>> - gic);
>> }
>>
>> if (WARN_ON(!gic->domain))
>
> Thanks,
>
> M.
>
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