Subject: Re: Problems with Kernels 3.17-rc1 and onwards on Acube Sam460 AMCC 460ex board

From: Julian Margetson <[email-masked]>
Date: Wed, 18 Feb 2015 21:36:07 -0400

On 2/18/2015 8:13 PM, Michael Ellerman wrote:
> On Wed, 2015-02-18 at 15:45 -0400, Julian Margetson wrote:
>> On 2/15/2015 8:18 PM, Michael Ellerman wrote:
>>
>>> On Sun, 2015-02-15 at 08:16 -0400, Julian Margetson wrote:
>>>> Hi
>>>>
>>>> I am unable to get any kernel beyond  the 3.16 branch working on an
>>>> Acube Sam460ex
>>>>   AMCC 460ex based motherboard. Kernel  up 3.16.7-ckt6 working.
>>> Does reverting b0345bbc6d09 change anything?
>>>
>>>> [    6.364350] snd_hda_intel 0001:81:00.1: enabling device (0000 -> 0002)
>>>> [    6.453794] snd_hda_intel 0001:81:00.1: ppc4xx_setup_msi_irqs: fail mapping irq
>>>> [    6.487530] Unable to handle kernel paging request for data at address 0x0fa06c7c
>>>> [    6.495055] Faulting instruction address: 0xc032202c
>>>> [    6.500033] Vector: 300 (Data Access) at [efa31cf0]
>>>> [    6.504922]     pc: c032202c: __reg_op+0xe8/0x100
>>>> [    6.509697]     lr: c0014f88: msi_bitmap_free_hwirqs+0x50/0x94
>>>> [    6.515600]     sp: efa31da0
>>>> [    6.518491]    msr: 21000
>>>> [    6.521112]    dar: fa06c7c
>>>> [    6.523915]  dsisr: 0
>>>> [    6.526190]   current = 0xef8bab00
>>>> [    6.529603]     pid   = 115, comm = kworker/0:1
>>>> [    6.534163] enter ? for help
>>>> [    6.537054] [link register   ] c0014f88 msi_bitmap_free_hwirqs+0x50/0x94
>>>> [    6.543811] [efa31da0] c0014f78 msi_bitmap_free_hwirqs+0x40/0x94 (unreliable)
>>>> [    6.551001] [efa31dc0] c001aee8 ppc4xx_setup_msi_irqs+0xac/0xf4
>>>> [    6.556973] [efa31e00] c03503a4 pci_enable_msi_range+0x1e0/0x280
>>>> [    6.563032] [efa31e40] f92c2f74 azx_probe_work+0xe0/0x57c [snd_hda_intel]
>>>> [    6.569906] [efa31e80] c0036344 process_one_work+0x1e8/0x2f0
>>>> [    6.575627] [efa31eb0] c003677c worker_thread+0x2f4/0x438
>>>> [    6.581079] [efa31ef0] c003a3e4 kthread+0xc8/0xcc
>>>> [    6.585844] [efa31f40] c000aec4 ret_from_kernel_thread+0x5c/0x64
>>>> [    6.591910] mon>  <no input ...>
>> Managed to do a third git bisect  with the following results .
> Great work.
>
>> git bisect bad
>> 9279d3286e10736766edcaf815ae10e00856e448 is the first bad commit
>> commit 9279d3286e10736766edcaf815ae10e00856e448
>> Author: Rasmus Villemoes <[email-masked]>
>> Date:   Wed Aug 6 16:10:16 2014 -0700
>>
>>      lib: bitmap: change parameter of bitmap_*_region to unsigned
>>      
>>      Changing the pos parameter of __reg_op to unsigned allows the compiler
>>      to generate slightly smaller and simpler code.  Also update its callers
>>      bitmap_*_region to receive and pass unsigned int.  The return types of
>>      bitmap_find_free_region and bitmap_allocate_region are still int to
>>      allow a negative error code to be returned.  An int is certainly capable
>>      of representing any realistic return value.
> So that looks feasible as the culprit.
>
> Looking at the 4xx MSI code, it just looks wrong:
>
> static int ppc4xx_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
> {
> 	...
>
> 	list_for_each_entry(entry, &dev->msi_list, list) {
> 		int_no = msi_bitmap_alloc_hwirqs(&msi_data->bitmap, 1);
> 		if (int_no >= 0)
> 			break;
>
> That's backward, a *negative* return indicates an error.
>
> 		if (int_no < 0) {
> 			pr_debug("%s: fail allocating msi interrupt\n",
> 					__func__);
> 		}
>
> This is the correct check, but it just prints a warning and then continues,
> which is not going to work.
>
> 		virq = irq_of_parse_and_map(msi_data->msi_dev, int_no);
>
> This will fail if int_no is negative.
>
> 		if (virq == NO_IRQ) {
> 			dev_err(&dev->dev, "%s: fail mapping irq\n", __func__);
> 			msi_bitmap_free_hwirqs(&msi_data->bitmap, int_no, 1);
>
> And so here we can pass a negative int_no to the free routine, which then oopses.
>
> 			return -ENOSPC;
> 		}
>
>
> So the bug is in the 4xx MSI code, and has always been there, in fact I don't
> see how that code has *ever* worked. The commit you bisected to just caused the
> existing bug to cause an oops.
>
> Can you try this?
>
> diff --git a/arch/powerpc/sysdev/ppc4xx_msi.c b/arch/powerpc/sysdev/ppc4xx_msi.c
> index 6e2e6aa378bb..effb5b878a78 100644
> --- a/arch/powerpc/sysdev/ppc4xx_msi.c
> +++ b/arch/powerpc/sysdev/ppc4xx_msi.c
> @@ -95,11 +95,9 @@ static int ppc4xx_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
>   
>   	list_for_each_entry(entry, &dev->msi_list, list) {
>   		int_no = msi_bitmap_alloc_hwirqs(&msi_data->bitmap, 1);
> -		if (int_no >= 0)
> -			break;
>   		if (int_no < 0) {
> -			pr_debug("%s: fail allocating msi interrupt\n",
> -					__func__);
> +			pr_warn("%s: fail allocating msi interrupt\n", __func__);
> +			return -ENOSPC;
>   		}
>   		virq = irq_of_parse_and_map(msi_data->msi_dev, int_no);
>   		if (virq == NO_IRQ) {
>
> cheers
>
>
>
>
Thanks.
This works with 3.17-rc1. Will try with the 3.18 Branch .
Any ideas why drm is not  working ? (It never worked) .

[    5.809802] Linux agpgart interface v0.103
[    6.137893] [drm] Initialized drm 1.1.0 20060810
[    6.439872] snd_hda_intel 0001:81:00.1: enabling device (0000 -> 0002)
[    6.508544] ppc4xx_setup_msi_irqs: fail allocating msi interrupt
[    6.652019] input: HDA ATI HDMI HDMI/DP,pcm=3 as /devices/pci0001:80/0001:80:                     00.0/0001:81:00.1/sound/card0/input3
[    7.091160] snd_ice1724 0000:42:00.0: No matching model found for ID 0x121403                     24
[    7.357382] [drm] radeon kernel modesetting enabled.
[    7.465477] [drm] initializing kernel modesetting (TURKS 0x1002:0x6758 0x1682                     :0x318B).
[    7.619111] [drm] register mmio base: 0xe90000000
[    7.675162] [drm] register mmio size: 131072
[    7.977217] ATOM BIOS: TURKS
[    7.980411] radeon 0001:81:00.0: VRAM: 1024M 0x0000000000000000 - 0x000000003                     FFFFFFF (1024M used)
[    7.989602] radeon 0001:81:00.0: GTT: 1024M 0x0000000040000000 - 0x000000007F                     FFFFFF
[    7.998154] [drm] Detected VRAM RAM=1024M, BAR=256M
[    8.003107] [drm] RAM width 128bits DDR
[    8.007196] [TTM] Zone  kernel: Available graphics memory: 380708 kiB
[    8.014116] [TTM] Zone highmem: Available graphics memory: 1036068 kiB
[    8.020685] [TTM] Initializing pool allocator
[    8.025093] [TTM] Initializing DMA pool allocator
[    8.030730] [drm] radeon: 1024M of VRAM memory ready
[    8.035793] [drm] radeon: 1024M of GTT memory ready.
[    8.040862] [drm] Loading TURKS Microcode
[    8.485902] [drm] Internal thermal controller with fan control
[    8.501363] [drm] radeon: dpm initialized
[    8.540582] [drm] GART: num cpu pages 262144, num gpu pages 262144
[    8.591547] [drm] PCIE GART of 1024M enabled (table at 0x0000000000273000).
[    8.615342] radeon 0001:81:00.0: WB enabled
[    8.620473] radeon 0001:81:00.0: fence driver on ring 0 use gpu addr 0x000000                     0040000c00 and cpu addr 0xc55d0c00
[    8.631217] radeon 0001:81:00.0: fence driver on ring 3 use gpu addr 0x000000                     0040000c0c and cpu addr 0xc55d0c0c
[    8.668198] radeon 0001:81:00.0: fence driver on ring 5 use gpu addr 0x000000                     0000072118 and cpu addr 0xf9832118
[    8.678526] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
[    8.685176] [drm] Driver supports precise vblank timestamp query.
[    8.691508] ppc4xx_setup_msi_irqs: fail allocating msi interrupt
[    8.697625] [drm] radeon: irq initialized.
[    8.727173] [drm] ring test on 0 succeeded in 1 usecs
[    8.923064] [drm:r600_dma_ring_test] *ERROR* radeon: ring 3 test failed (0xCA                     FEDEAD)
[    8.931197] radeon 0001:81:00.0: disabling GPU acceleration