Message-ID: <20071122203135.qjoylea4gwc8cs08@webmail.jpl.nasa.gov>
Date:	Thu, 22 Nov 2007 20:31:35 -0800
From:	niessner@....nasa.gov
To:	Marin Mitov <mitov@...p.bas.bg>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: Where is the interrupt going?


Quite right. I read it too quickly and thought it had succeeded when  
it had failed. I will modify the module to do the shared IRQ and then  
try the noapic test again. Exactly why I reserved the right to do it  
again.

This is good because it means the hammer may work after all.

Thank you very much and I will post to let you know the outcome.

Quoting Marin Mitov <mitov@...p.bas.bg>, on Thu 22 Nov 2007 07:18:01 PM PST:

> Hi,
>
> On Friday 23 November 2007 02:48:53 am you wrote:
>> I tried the hammer and the problem persists.
>> observer@bbb:~$ cat /proc/cmdline
>> root=UUID=8b3c3666-22c3-4c04-b399-ece266f2ef30 ro noapic quiet splash
>>
>> However, I reserve the right to try the hammer again in the future.
>> When I look at /proc/interrupts without the APIC:
>> observer@bbb:~$ cat /proc/interrupts
>>             CPU0
>>    0:        144    XT-PIC-XT        timer
>>    1:         10    XT-PIC-XT        i8042
>>    2:          0    XT-PIC-XT        cascade
>>    5:     100000    XT-PIC-XT        ohci_hcd:usb5, mxser
>>    6:          5    XT-PIC-XT        floppy
>>    7:          1    XT-PIC-XT        parport0
>>    8:          3    XT-PIC-XT        rtc
>>    9:          1    XT-PIC-XT        acpi, uhci_hcd:usb2
>>   10:     100000    XT-PIC-XT        ohci_hcd:usb4, ehci_hcd:usb6,
>> r128@pci:0000:01:00.0
>>   11:       2231    XT-PIC-XT        uhci_hcd:usb1, ohci_hcd:usb3, eth0
>>   12:        130    XT-PIC-XT        i8042
>>   14:       4362    XT-PIC-XT        libata
>>   15:      15315    XT-PIC-XT        libata
>> NMI:          0
>> LOC:     130125
>> ERR:          0
>> MIS:          0
>>
>> I do not even see the device that I registered unless it is that
>> r128... line. However the code printed out in /var/log/messages:
>
> No, this is your radeon 128 board (on AGP I suppose). Could be integrated
> on the mobo if it is a server mobo.
>
>> Nov 22 16:05:27 bbb kernel: [  104.712473] apc8620: VID = 0x10B5
>> Nov 22 16:05:27 bbb kernel: [  104.712486] apc8620: mapped addr = e0bd4000
>> Nov 22 16:05:27 bbb kernel: [  104.713022] apc8620: registered carrier 0
>> Nov 22 16:05:27 bbb kernel: [  104.713028] apc8620: interrupt data
>> (0xe1083e40) on irq (10) and status (0x10)
>
> Here is the problem (I suppose):
> if status (0x10 hex or 16 decimal) is the value returned by request_irq:
> status = request_irq (apcsi[i].board_irq,
>                                       apc8620_handler,
>                                       IRQF_DISABLED,
>                                       DEVICE_NAME,
>                                       (void*)&apcsi[i]);
> (from your first post), that means the irq is NOT registered, because
> according to the LDD v.3 book:
> <cite>
> The value returned from request_irq to the requesting function is either 0
> to indicate success or a negative error code, as usual. It’s not uncommon
> for the function to return -EBUSY to signal that another driver is already
> using the requested interrupt line.
> </cite>
> If you grep the kernels's include directory for EBUSY you will find:
> #define        EBUSY           16      /* Device or resource busy */
> in include/asm-generic/errno-base.h
>
> So I think your mobo has shared (with other devices) irq line on the
> PCI/PCIe slot you use for your hardware and these other devices have
> already registered shered irq handlers for the same irq (10), so the
> attempt to register nonshared irq fails.
>
> Either try to register the irq as shared, or put the hardware on
> another slot whose irq line is not shared with other devises
> (if such one exists). This info should be available from the mobo
> manual book.
>>
>> which indicates it successfully registered without being shared.
>
> No, as I already explained.
> The only problem :-) in my explanation is:
> request_irq returns EBUSY (not -EBUSY as should be)
>
> Marin Mitov
>
>> When
>> I have more time, I will changed the code to be a shared IRQ and try
>> the noapic again.
>>
>> However, without the noapic /proc/interrupts looks like:
>> observer@bbb:~$ cat /proc/interrupts
>>             CPU0
>>    0:        154   IO-APIC-edge      timer
>>    1:         10   IO-APIC-edge      i8042
>>    6:          5   IO-APIC-edge      floppy
>>    7:          0   IO-APIC-edge      parport0
>>    8:          3   IO-APIC-edge      rtc
>>    9:          1   IO-APIC-fasteoi   acpi
>>   10:          0   IO-APIC-edge      apc8620
>>   12:        130   IO-APIC-edge      i8042
>>   14:       2861   IO-APIC-edge      libata
>>   15:       1049   IO-APIC-edge      libata
>>   16:     100001   IO-APIC-fasteoi   ohci_hcd:usb5, mxser
>>   17:          0   IO-APIC-fasteoi   uhci_hcd:usb1, ohci_hcd:usb3
>>   18:          0   IO-APIC-fasteoi   uhci_hcd:usb2
>>   19:        187   IO-APIC-fasteoi   eth0
>>   20:          0   IO-APIC-fasteoi   ohci_hcd:usb4, r128@pci:0000:01:00.0
>>   21:          0   IO-APIC-fasteoi   ehci_hcd:usb6
>> NMI:          0
>> LOC:       8820
>> ERR:          0
>> MIS:          0
>>
>>
>> I have attached the kernel module. The apc8620 is an IndustryPack
>> carrier card. I can therefore open up N (in this specific case 5) sub
>> memory windows in the memory mapped PCI address. The kernel module
>> keeps track of the slot offsets from the memory mapped address so that
>> the user can simply use read and write instead of a zillion ugly ioctl
>> calls. Because the kernel module tracks the slot offsets, I place acp
>> state into the private data of the file pointer. There can also be
>> multiple carriers on the bus. So, the array in the kernel module keeps
>> track of the card specific details with the file pointer the slot
>> specific information. Both are the same structure (bad on my part I
>> know but I never intended to show my dirty underwear). To get data
>> from interrupts (asynchronous IO) I was using readv. Now I am using
>> aio_read and had to make some minor changes that you will see comments
>> about to accomidate the change.
>>
>> Just noticed that r128 is not the carrier card...
>>
>> Thanks for all of the help so far and I hope this information is helpful.
>>
>> I almost forgot. I also attached the dmesg output and will try the
>> irqpoll as it suggests. It is just the IRQ 16 is not the one I am
>> looking for, but is probably related to my mxser problems that I will
>> get to later.
>>
>> Quoting Kyle McMartin <kyle@...artin.ca>, on Wed 21 Nov 2007 06:20:04 PM
> PST:
>> > On Wed, Nov 21, 2007 at 05:08:30PM -0800, Al Niessner wrote:
>> >> On with the detailed technical information. I developed a kernel module
>> >> for an PCI card back in 2.4, moved it to 2.6.3, then 2.6.11 or so and
>> >> now I am trying to move it to 2.6.22. When I began the to move to
>> >> 2.6.22, I changed all of the deprecated calls for finding the card on
>> >> the PCI bus, modified the interrupt handler prototype, and changed my
>> >> readvv/writev to aio_read/aio_write following
>> >> http://lwn.net/Articles/202449/. So initialization looks like this:
>> >
>> > Hi Al,
>> >
>> > From the sounds of it, you might have an interrupt routing problem. Can
>> > you describe the machine you have this plugged into? Possibly attaching
>> > a copy of "dmesg" and "/proc/interrupts"?
>> >
>> > Feel free to attach the driver source to your email if the size is
>> > reasonable (which it sounds like it is.)
>> >
>> > As a "big hammer" in case it is an APIC problem, please try booting the
>> > kernel with the "noapic" parameter.
>> >
>> > cheers,
>> > 	Kyle
>
>
>


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