Ipipe req_bufs failed

Stephen Berry swb at i-d-2.com
Wed Sep 3 15:09:18 CDT 2008



Karicheri, Muralidharan wrote:
>
>  
>
>  
>
> Murali Karicheri
>
> Software Design Engineer
>
> Texas Instruments Inc.
>
> Germantown, MD 20874
>
> Phone : 301-515-3736
>
> email: m-karicheri2 at ti.com
>
> ------------------------------------------------------------------------
>
> *From:* Stephen Berry [mailto:swb at i-d-2.com]
> *Sent:* Tuesday, September 02, 2008 10:37 AM
> *To:* Karicheri, Muralidharan
> *Cc:* pavelhan; davinci-linux-open-source
> *Subject:* Re: Ipipe req_bufs failed
>
>  
>
> There are a bunch of issues using kernel memory space. Even when you 
> do have enough to use for a large 5Mpix buffer (which is 10MB) it 
> seems to get fragmented over time. So while you might be able to 
> allocate it once, once it gets freed all bets are off the next time 
> you want to use it.
>
> In addition there is a problem with buffers that large to begin with. 
> There is a #define in the kernel, the name of which escapes me at the 
> moment, which defines the largest page size you can allocate, and it's 
> too small. Changing it recompiles everything in the kenel, and was 
> just a little scary...
>
> Also, I remember that I've had issues with CMEM and V4l2. Last time I 
> tried to pass in a USERPTR to the V4L2 (and vpfe) all of my DQBUF 
> calls failed.
>
> */[MK] Have you tried increasing the size of kernel buffers allocated 
> by V4L2 capture? This will allocate at init time and reserve the 
> pages. You could then use the ptr from DQBUF to pass to ipipe driver. 
> V4L2 capture currently support only mmaped IO./*
>
>
I have tried this, but there is a drawback to this method. The V4l2 
driver will not let me only allocate only 1 buffer - the minimum is two. 
This is a fairly large waste of memory when I only need one buffer for 
still 5MP captures. I also need to be flexible with resolutions, since I 
want to be able to capture video at vga & HD, so I will need 3 buffers - 
but they don't need to be 10MB each!!

I'll figure away around this (like subdividing up a large buffer for the 
lower res), but it's not as nice as feeding memory pointers into the V4l2...

> Are there any examples on how to use CMEM with V4l2?
>
>     Steve
>
> Karicheri, Muralidharan wrote:
>
> Hello,
>
> You are actually reducing the memory available to kernel by setting 
> mem=80M. What you might want to do is to allocate memory using CMEM 
> and use it instead of req_buf.  Request buffer allocates memory from 
> kernel memory space. Otherwise, use bigger kernel memory instead of 
> reducing it.
>
>  
>
> *From:* davinci-linux-open-source-bounces at linux.davincidsp.com 
> <mailto:davinci-linux-open-source-bounces at linux.davincidsp.com> 
> [mailto:davinci-linux-open-source-bounces at linux.davincidsp.com] *On 
> Behalf Of *pavelhan
> *Sent:* Tuesday, September 02, 2008 5:52 AM
> *To:* davinci-linux-open-source
> *Subject:* Ipipe req_bufs failed
>
>  
>
> Hi everyone!
>
> I want to get a full resolution 5MP(2592x1944) picture from my MT9p031 
> sensor.
>
> but I failed when I req_buffers in the ipipe initialization procedure.
>
> I allocate a 80M memory to my linux in the bootargs(mem=80M),so I 
> think there is
>
> a enough space for I allocate 1 5MP ipipe buffer from linux(which will 
> require about
>
> 10M bytes),but when I execute the program, I only get the following 
> errors:
>
>  
>
> starting mt9p001_ipipe_init
>
> IPIPE idm355_ipipe dm355_ipipe.2: 4.request_buffer:not                         
>
> enough memory
>
> nit
>
> IPIPE_REQBUF fail
>
> IPIPE init fail
>
>  
>
> what should I do to get the problem solved?
>
> any help will be appreciated!
>
> Thank you!
>
>  
>
> 2008-09-02
>
> ------------------------------------------------------------------------
>
>  
>
>  
>
> Pavel Han
>
> Oplinx Co.,Ltd
>
> Address:Hanggang Fuchun Business Mansion 2116# Futian, Shenzhen 518041,PRC
>
> Tel: (086)0755-88359865
>
> Website:www.oplinx.com.cn
>
> E-mail: pavelhan at oplinx.com <mailto:pavelhan at oplinx.com> 
>
>  
>
>
> ------------------------------------------------------------------------
>
>
>  
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