[Linaro-mm-sig] [PATCH] dma-buf: Add debugfs support

[Sumit Semwal]

On 17 December 2012 14:25, Sumit Semwal <sumit.semwal at linaro.org> wrote:
Apologies for re-sending, since the gmail ui 'decided' to set some
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> Hi Maarten,
>
> On 14 December 2012 17:27, Maarten Lankhorst <m.b.lankhorst at gmail.com>
> wrote:
>>
>> Op 14-12-12 10:36, sumit.semwal at ti.com schreef:
>> > From: Sumit Semwal <sumit.semwal at linaro.org>
>> >
>> > Add debugfs support to make it easier to print debug information
>> > about the dma-buf buffers.
>> >
>> I like the idea, I don't know if it could be done in a free manner, but
>> for bonus points
>> could we also have the dma-buf fd be obtainable that way from a debugfs
>> entry?
>>
>> Doing so would allow me to 'steal' a dma-buf from an existing mapping
>> easily, and test against that.
>>
>> Also I think the name of the device and process that exported the dma-buf
>> would be useful
>> to have as well, even if in case of the device that would mean changing
>> the api slightly to record it.
>>
>> I was thinking of having a directory structure like this:
>>
>> /sys/kernel/debug/dma_buf/stats
>>
>> and then for each dma-buf:
>>
>> /sys/kernel/debug/dma-buf/exporting_file.c/<number>-fd
>> /sys/kernel/debug/dma-buf/exporting_file.c/<number>-attachments
>> /sys/kernel/debug/dma-buf/exporting_file.c/<number>-info
>>
>> Opening the fd file would give you back the original fd, or fail with -EIO
>> if refcount was dropped to 0.
>>
>> Would something like this be doable? I don't know debugfs that well, but I
>> don't see why it wouldn't be,
>
> Let me think more about it, but I am inclined to add simple support first,
> and then add more features to dma_buf debugfs as it grows.
>
> I still would want to take Daniel's suggestion on dma_buf_export_named()
> before I push this patch, so I guess I'll try to work a little more and
> prepare it for 3.9?
>
> I quite like your idea of .../dma-buf/<exporting_file.c>/...  , which would
> need the above as well :)
>>
>>
>> ~Maarten
>>
> Best regards,
> ~Sumit.
>



--
Thanks and regards,

Sumit Semwal

Linaro Kernel Engineer - Graphics working group

Linaro.org │ Open source software for ARM SoCs

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