Steven A. Falco wrote:
> On 01/05/2011 04:33 PM, Gilles Chanteperdrix wrote:
>> Herrera-Bendezu, Luis wrote:
>>> Gilles:
>>>
>>>> Herrera-Bendezu, Luis wrote:
>>>>> Hello:
>>>>>
>>>>> I have the following setup:
>>>>> PPC405EX
>>>>> Linux 2.6.30.3
>>>>> Xenomai 2.4.10
>>>>> I-pipe 2.7-02
>>>>> ppc_4xx-gcc (GCC) 4.2.2
>>>>> Configuration file is attached
>>>> Do you have the same issue with the latest version of the I-pipe patch
>>>> for this same version of the Linux kernel? It should be 2.8-00.
>>> Tried I-pipe 2.8-00 which needs Linux 2.6.32.
>> Sorry, I misread the ftp list, I was rather thinking about:
>> http://download.gna.org/adeos/patches/v2.6/powerpc/older/adeos-ipipe-2.6.30.3-powerpc-DENX-2.7-06.patch
>>
>>
>> It resulted on same problem
>>> as reported with Linux 2.6.30.3 I-pipe 2.7-02.
>>>
>>> Was there any particular set of changes that you expected it could fix the
>>> problem? Do you think more recent versions may work? If yes, which version
>>> could be tried?
>> Yes, there was a fix, specifially in the powerpc tree, with mappings
>> issue. But I think it is older than 2.6.32.
>>
>> Now that I look at your message again, your problem seems more likely to
>> be in your code. Specifically, you say: "bus address returned by
>> pci_alloc_consistent()". I do not think pci_alloc_consistent return
>> value is a bus address. The dma_handle returned by pointer probably is.
>> But I am not sure you are supposed to know this.
>
> pci_alloc_consistent() returns two values. The kernel address is
> returned directly (as a void *), and the bus address is returned
> through the dma_handle pointer (third function argument).
>
> Luis' original email indicated that he tried rtdm_mmap_to_user()
> on the kernel address, and he tried rtdm_iomap_to_user() on the
> bus address. Either way caused the crash he reported.
Ok. Could you try to do the same operation with the native API? You just
have to pass H_SHARED | H_DMA | H_NONCACHED as flags to rt_heap_create
to get the same effect as pci_dma_alloc_coherent.
Just to see if the error lies in RTDM implementation or in Xenomai
generic code.
>
> We have a home-grown program (mm) that basically opens /dev/mem
> and allows peek/poke. Using that with the bus address works to
> access the memory. We also pass that address to our hardware,
> and it correctly DMAs the data. So we believe the bus address
> is correct.
You mean much like devmem2? Now even part of the busybox?
>
> I believe Luis has also tried a third approach - allocating with
> kzalloc(size, GFP_DMA), and using rtdm_mmap_to_user() on the
> resulting pointer. That works, but getting the bus address is
> a bit ugly - basically page_to_phys(virt_to_page()) of the pointer.
>
> So there is something different about the way pci_alloc_consistent()
> allocates memory as compared to kzalloc(GFP_DMA). kzalloc(GFP_DMA)
> works with rtdm_mmap_to_user() but pci_alloc_consistent() does
> not.
This gives me an idea. Could you try the following patch? Even before
trying the native API.
diff --git a/ksrc/skins/rtdm/drvlib.c b/ksrc/skins/rtdm/drvlib.c
index 3495e63..d7dd3db 100644
--- a/ksrc/skins/rtdm/drvlib.c
+++ b/ksrc/skins/rtdm/drvlib.c
@@ -1810,7 +1810,7 @@ static int rtdm_mmap_buffer(struct file *filp, struct
vm_area_struct *vma)
vaddr = (unsigned long)mmap_data->src_vaddr;
paddr = mmap_data->src_paddr;
if (paddr == 0) /* kmalloc memory? */
- paddr = __pa(vaddr);
+ paddr = page_to_phys(virt_to_page(vaddr));
maddr = vma->vm_start;
size = vma->vm_end - vma->vm_start;
--
Gilles.
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