Re: [PATCH 02/19] dma-buf-map: Add helper to initialize second map

[Thomas Zimmermann <tzimmermann@xxxxxxx>]

Hi

Am 28.01.22 um 09:15 schrieb Thomas Zimmermann:
...
> > While with the construct below
> >
> >          other_map;
> >          ...
> >          other_map = INITIALIZER()
> >
> > I can rely on the compiler complaining about uninitialized var. And
> > in most of the cases I can just have this single line in the beggining 
> > of the
> > function when the offset is constant:
> >
> >          struct dma_buf_map other_map = INITIALIZER(bla_map, 
> > offsetof(..));
> >
> >
> > This is useful when you have several small functions in charge of
> > updating/reading inner struct members.
>
> You won't need an extra variable or the initializer macro if you add an 
> offset parameter to dma_buf_memcpy_{from,to}.  Simple pass offsetof(..) 
> to that parameter and it will do the right thing.
>
> It avoids the problems of the current macro and is even more flexible. 
> On top of that, you can build whatever convenience macros you need for 
> i915.

And maybe put all changes to the dma_buf_map interface into a single 
patch. It makes it easier to review and discuss.

Best regards
Thomas

> Best regards
> Thomas
>
> > > I've also been very careful to distinguish between .vaddr and 
> > > .vaddr_iomem, even in places where I wouldn't have to. This macro 
> > > breaks the assumption.
> >
> > That's one reason I think if we have this macro, it should be in the
> > dma_buf_map.h header (or whatever we rename these APIs to). It's the
> > only place where we can safely add code that relies on the implementation
> > of the "private" fields in struct dma_buf_map.
> >
> > Lucas De Marchi
> >
> > > Best regards
> > > Thomas
> > >
> > > >  /**
> > > >   * dma_buf_map_set_vaddr - Sets a dma-buf mapping structure to an 
> > > > address in system memory
> > > >   * @map:    The dma-buf mapping structure
> > >
> > > --
> > > Thomas Zimmermann
> > > Graphics Driver Developer
> > > SUSE Software Solutions Germany GmbH
> > > Maxfeldstr. 5, 90409 Nürnberg, Germany
> > > (HRB 36809, AG Nürnberg)
> > > Geschäftsführer: Ivo Totev

--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev

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