[GitHub] [incubator-nuttx] patacongo edited a comment on issue #439: Video: Correct use of global variable

[GitBox <gi...@apache.org>]

patacongo edited a comment on issue #439:
URL: https://github.com/apache/incubator-nuttx/issues/439#issuecomment-642640881


   A related issus the the use, or rather the lacke of the use of the video driver initialization function:  video_initialize().
   
   That function should be called from the board bringup() functions but it is not.  In fact, it is not called from anywhere in the OS.  Searching a little, we find that it is insanely called from the Sony SDK applications directly.  That is very bad design:  Calling directly into the OS from application bypassing the portable, POSIX interface is strictly forbidden.  From the INVIOLABLES.txt:
   
       Strict POSIX compliance
       -----------------------
       
         o Strict conformance to the portable standard OS interface as defined at
           OpenGroup.org.
         o The portable interface must never be compromised only for the sake of
           expediency.
         o Expediency or even improved performance are not justifications for
           violation of the strict POSIX interface.
   
   My recommendation is:
   
   1. Remove the direct call to video_initialize() from the SDK application.  It is not needed.
   2. Add the call to video_initialize() to the spresense bringup() logic.
   3. Remove the (now extern'ed) global variable g_video_devops from include/nuttx/video/video.h and mark the g_video_devops global variable in drivers/video/video.c as static
   4. Add a : FAR const struct video_devops_s *devops argument to video_initialize()
   5. Provide the video_devops_s instance to the driver with video_initialize() in the spresense bringup() function.
   
   The current situation is intolerable and must be corrected!
   


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