[PATCH weston] compositor-fbdev: enumerate available fbdevs using udev

[Ryo Munakata]

On Wed, 11 Mar 2015 16:05:55 +0200
Pekka Paalanen <ppaalanen at gmail.com> wrote:

> On Tue, 10 Mar 2015 11:34:45 +0900
> Ryo Munakata <ryomnktml at gmail.com> wrote:
> 
> > This was a TODO:
> > "Ideally, available frame buffers should be enumerated
> > using udev, rather than passing a device node in as a
> > parameter."
> 
> Hi,
> 
> I'm CC'ing the person responsible for the TODO-comment.
> 
> > 
> > Signed-off-by: Ryo Munakata <ryomnktml at gmail.com>
> > ---
> >  src/compositor-fbdev.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++---
> >  1 file changed, 52 insertions(+), 3 deletions(-)
> > 
> > diff --git a/src/compositor-fbdev.c b/src/compositor-fbdev.c
> > index eedf252..c0e6985 100644
> > --- a/src/compositor-fbdev.c
> > +++ b/src/compositor-fbdev.c
> > @@ -46,6 +46,8 @@
> >  #include "gl-renderer.h"
> >  #include "presentation_timing-server-protocol.h"
> >  
> > +#define FBDEV_MAJOR_NUMBER (29)
> > +
> >  struct fbdev_compositor {
> >  	struct weston_compositor base;
> >  	uint32_t prev_state;
> > @@ -690,6 +692,9 @@ fbdev_output_destroy(struct weston_output *base)
> >  		gl_renderer->output_destroy(base);
> >  	}
> >  
> > +	if (output->device)
> > +		free((char *)output->device);
> 
> No need to cast. Also no need for 'if' because free(NULL) is perfectly
> legal.

This cast causes a warning like:
 src/compositor-fbdev.c:696:7: warning: passing argument 1 of ‘free’ discards ‘const’ qualifier from pointer target type
I think we need it for silencing the warning.
What do you think?

And yes, that if statement is unnecessary. I'll fix it.

> > +
> >  	/* Remove the output. */
> >  	weston_output_destroy(&output->base);
> >  
> > @@ -748,6 +753,7 @@ fbdev_output_reenable(struct fbdev_compositor *compositor,
> >  		 * the frame buffer X/Y resolution (such as the shadow buffer)
> >  		 * are re-initialised. */
> >  		device = output->device;
> > +		output->device = NULL;
> 
> Why NULLing it here? Seem like this would make repeated reenable to
> fail, no?

Here we reuse output->device for the new output. (device = output->device;)
output->device is allocated by strdup() dynamically and fbdev_output_destroy() frees it if not NULL.
So if you don't set output->device as NULL we need to reallocate and copy the entire device string for the new output everytime this function is called.
This is why I set output->device as NULL to prevent it.

> >  		fbdev_output_destroy(base);
> >  		fbdev_output_create(compositor, device);
> >  

Thank you.
-- 
Ryo Munakata <ryomnktml at gmail.com>