Re: clk: Two-output clk provider with standard clk consumer
On 13/10/2015 14:30, Mason wrote:
> So the device tree would look like this:
>
> clocks {
> ranges;
> #address-cells = <1>;
> #size-cells = <1>;
>
> xtal: xtal {
> compatible = "fixed-clock";
> clock-frequency = <2700>;
> #clock-cells = <0>;
> };
>
> clkgen: clkgen@1 {
> compatible = "foo,clkgen";
> reg = <0x1 0x30>;
> clocks = <&xtal>;
> #clock-cells = <1>;
Missing clock-output-names property here.
> };
>
> periphclk: periphclk {
> compatible = "fixed-factor-clock";
> clocks = <&clkgen 0>;
> clock-mult = <1>;
> clock-div = <2>;
> #clock-cells = <0>;
> };
> };
Sorry for the noise.
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Re: Enable/disable cpu
Doug Wilson writes:
> All,
>
> I have been looking at sysfs cpu side code. Had a quick question.
>
> On my x86 box:
> #ls /sys/devices/system/cpu/
> I see 4 cpus plus a few more fields such as online/present/possible etc.
>
> This come from drivers/base/cpu.c.
>
> My question here is, in each of those cpu0-3 folders, there's file by name
> online which one can use to disable/enable cpu using cpumask. Could
> someone point me to that code, I could not really pin point to where exactly
> this attribute is defined. Am just exploring cpu hotplug feature.
drivers/base/core.c has this generic code for creating that file:
if (device_supports_offline(dev) && !dev->offline_disabled) {
error = device_create_file(dev, &dev_attr_online);
if (error)
goto err_remove_dev_groups;
}
where device_supports_offline is:
static inline bool device_supports_offline(struct device *dev)
{
return dev->bus && dev->bus->offline && dev->bus->online;
}
and the cpu "bus" is (from drivers/base/cpu.c):
struct bus_type cpu_subsys = {
.name = "cpu",
.dev_name = "cpu",
.match = cpu_subsys_match,
#ifdef CONFIG_HOTPLUG_CPU
.online = cpu_subsys_online,
.offline = cpu_subsys_offline,
#endif
};
The fields of the cpu device are initialized in drivers/base/cpu.c:
int register_cpu(struct cpu *cpu, int num)
{
int error;
cpu->node_id = cpu_to_node(num);
memset(&cpu->dev, 0x00, sizeof(struct device));
cpu->dev.id = num;
cpu->dev.bus = &cpu_subsys;
cpu->dev.release = cpu_device_release;
cpu->dev.offline_disabled = !cpu->hotpluggable;
cpu->dev.offline = !cpu_online(num);
cpu->dev.of_node = of_get_cpu_node(num, NULL);
#ifdef CONFIG_GENERIC_CPU_AUTOPROBE
cpu->dev.bus->uevent = cpu_uevent;
#endif
cpu->dev.groups = common_cpu_attr_groups;
if (cpu->hotpluggable)
cpu->dev.groups = hotplugable_cpu_attr_groups;
error = device_register(&cpu->dev);
if (!error)
per_cpu(cpu_sys_devices, num) = &cpu->dev;
if (!error)
register_cpu_under_node(num, cpu_to_node(num));
return error;
}
So you get the "online" file in the cpuX folders when CONFIG_HOTPLUG_CPU
is defined and cpu->hotpluggable is true. Which will exclude cpu0 in
some cases. See arch/x86/kernel/topology.c for the x86 specific logic
concerning that. I assume other platforms have similar exceptions
Bjørn
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Re: System freezes with Kernel BUG at kernel/time/timer.c:1108 run_timer_softirq()
On Wed, Oct 14, 2015 at 11:02 AM, Raghavendra. S wrote: > > Hi, > > In my x86 laptop I could observe random panic with Fatal exception in > interrupt. We are testing Wi-Fi with our own driver issue occur randomly > after 2-3 hours of testing. > > Panic is due to fatal except in interrupt and Kernel stack trace is > run_timer_softirq()->__run_timers()->cascade()->BUG_ON(tbase_get_base(timer->base) > != base); > > > > > > Any pointers to debug this will be of great help. > > > -Raghu > First of all, please send email using plain text mode. If you need to send picture, better attach it to somewhere else and provide us with the link. I am just guessing: it might be that when timer is about to run or in the middle of running, the data structure that represents the timer gets deleted. Sounds like race condition then. -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: How to reserve physical address space region
On Fri, Oct 16, 2015 at 10:53 AM, sahlot arvind wrote: > Hi, > > Is there an API kernel exposes to use for a driver in order to reserve > physical address space? > I mean I want to reserve 5GB (or more if allowed) of contiguous physical > address space anywhere in the address range (wherever it is available.. > doesn't matter) and then I want to map that physical address range in the > kernel to get a virtual address so that my driver can dereference that > virtual pointer to access the mapped physical address range. > > Thanks in advance! > Sahlot > 5 GB is alot. If you are sure about it, then I guess boot_memalloc() might be the only choice -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: How to reserve physical address space region
Have you looked at the uio driver examples? Also, LDD3 may be old, but the API is at least still relevant. The explanation is too long to include here, but the book is free :D On Thu, Oct 15, 2015 at 11:53 PM, sahlot arvind wrote: > Hi, > > Is there an API kernel exposes to use for a driver in order to reserve > physical address space? > I mean I want to reserve 5GB (or more if allowed) of contiguous physical > address space anywhere in the address range (wherever it is available.. > doesn't matter) and then I want to map that physical address range in the > kernel to get a virtual address so that my driver can dereference that > virtual pointer to access the mapped physical address range. > > Thanks in advance! > Sahlot > > ___ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > > ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Enable/disable cpu
All, I have been looking at sysfs cpu side code. Had a quick question. On my x86 box: #ls /sys/devices/system/cpu/ I see 4 cpus plus a few more fields such as online/present/possible etc. This come from drivers/base/cpu.c. My question here is, in each of those cpu0-3 folders, there's file by name online which one can use to disable/enable cpu using cpumask. Could someone point me to that code, I could not really pin point to where exactly this attribute is defined. Am just exploring cpu hotplug feature. Thanks. ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
How to reserve physical address space region
Hi, Is there an API kernel exposes to use for a driver in order to reserve physical address space? I mean I want to reserve 5GB (or more if allowed) of contiguous physical address space anywhere in the address range (wherever it is available.. doesn't matter) and then I want to map that physical address range in the kernel to get a virtual address so that my driver can dereference that virtual pointer to access the mapped physical address range. Thanks in advance! Sahlot ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
