Re: [PATCH v2] DRM: add drm gem cma helper

[InKi Dae <daeinki@gmail.com>]

2012/6/5 Sascha Hauer <s.hauer@pengutronix.de>:
> On Fri, Jun 01, 2012 at 12:29:47AM +0900, InKi Dae wrote:
>> Hi Sascha,
>>
>> >> +struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm,
>> >> +             unsigned int size)
>> >> +{
>> >> +     struct drm_gem_cma_object *cma_obj;
>> >> +     struct drm_gem_object *gem_obj;
>> >> +     int ret;
>> >> +
>> >> +     size = round_up(size, PAGE_SIZE);
>> >> +
>> >> +     cma_obj = kzalloc(sizeof(*cma_obj), GFP_KERNEL);
>> >> +     if (!cma_obj)
>> >> +             return ERR_PTR(-ENOMEM);
>> >> +
>> >> +     cma_obj->vaddr = dma_alloc_writecombine(drm->dev, size,
>> >> +                     &cma_obj->paddr, GFP_KERNEL | __GFP_NOWARN);
>>
>> how about calling drm_gem_cma_buf_allocate() instead of
>> dma_alloc_wirtecombine() for consistency in using dma api so its call
>> flow would be "dma_gem_cma_buf_allocate() ->
>> dma_alloc_writecombine()".
>
> What do you mean? There is no drm_gem_cma_buf_allocate() function.
>

I mean have a pair with drm_gem_cma_buf_destroy() otherwise how about
removing dem_gem_cma_buf_destroy() and calling dma_free_writecombine()
directly? drm_gem_cma_buf_destroy() is just a wrapper to
dma_free_writecombine().

>> >> +     struct drm_gem_object *gem_obj;
>> >> +     struct drm_gem_cma_object *cma_obj;
>> >> +     int ret;
>> >> +
>> >> +     ret = drm_gem_mmap(filp, vma);
>> >> +     if (ret)
>> >> +             return ret;
>> >> +
>> >> +     gem_obj = vma->vm_private_data;
>> >> +     cma_obj = to_drm_gem_cma_obj(gem_obj);
>>
>> it's likely to need checking if user space size is valid or not here.
>> like this;
>> if (vma->end - vma->start > gem_obj->size) {
>>           error message;
>>          and some exceptions;
>> }
>
> This is already done in drm_gem_mmap().
>
> Sascha
>
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