Hi Daniel,
On Tuesday, November 5, 2019 3:27:55 PM CET Daniel Vetter wrote:
> On Thu, Oct 31, 2019 at 09:29:56AM +0100, Janusz Krzysztofik wrote:
> > We need dmabuf specific pwrite() callback utilizing dma-buf API,
> > otherwise GEM_PWRITE IOCTL will no longer work with dma-buf backed
> > (i.e., PRIME imported) objects on hardware with no mappable aperture.
> >
> > Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik@xxxxxxxxxxxxxxx>
> > Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@xxxxxxxxx>
> > Cc: Michal Wajdeczko <michal.wajdeczko@xxxxxxxxx>
>
> Do we have userspace for this (aside from igts)? Specifically for the
> gen12 + dma-buf import + pwrite/read/whatever case you're fixing in this
> series here.
I don't know the answer, sorry, I can only tell that prime_vgem IGT test uses
gem_read()/gem_write(), which call I915_GEM_PREAD/I915_GEM_PWRITE DRM IOCTLs
respectively, on PRIME imported vgem objects.
Thanks,
Janusz
> -Daniel
>
> > ---
> > drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 55 ++++++++++++++++++++++
> > 1 file changed, 55 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
> > index 96ce95c8ac5a..93eea1031c82 100644
> > --- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
> > +++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
> > @@ -248,9 +248,64 @@ static void i915_gem_object_put_pages_dmabuf(struct drm_i915_gem_object *obj,
> > DMA_BIDIRECTIONAL);
> > }
> >
> > +static int i915_gem_object_pwrite_dmabuf(struct drm_i915_gem_object *obj,
> > + const struct drm_i915_gem_pwrite *args)
> > +{
> > + struct dma_buf *dmabuf = obj->base.import_attach->dmabuf;
> > + void __user *user_data = u64_to_user_ptr(args->data_ptr);
> > + struct file *file = dmabuf->file;
> > + const struct file_operations *fop = file->f_op;
> > + void __force *vaddr;
> > + int ret;
> > +
> > + if (fop->write) {
> > + loff_t offset = args->offset;
> > +
> > + /*
> > + * fop->write() is supposed to call dma_buf_begin_cpu_access()
> > + * if O_SYNC flag is set, avoid calling it twice
> > + */
> > + if (!(file->f_flags & O_SYNC)) {
> > + ret = dma_buf_begin_cpu_access(dmabuf, DMA_TO_DEVICE);
> > + if (ret)
> > + return ret;
> > + }
> > +
> > + ret = fop->write(file, user_data, args->size, &offset);
> > +
> > + if (!(file->f_flags & O_SYNC))
> > + dma_buf_end_cpu_access(dmabuf, DMA_TO_DEVICE);
> > +
> > + if (!ret)
> > + return 0;
> > + }
> > +
> > + /* dma-buf file .write() not supported or failed, try dma_buf_vmap() */
> > + ret = dma_buf_begin_cpu_access(dmabuf, DMA_TO_DEVICE);
> > + if (ret)
> > + return ret;
> > +
> > + vaddr = dma_buf_vmap(dmabuf);
> > + if (!vaddr)
> > + goto out_err;
> > +
> > + ret = copy_from_user(vaddr + args->offset, user_data, args->size);
> > + dma_buf_vunmap(dmabuf, vaddr);
> > + if (!ret)
> > + goto out_end;
> > +
> > +out_err:
> > + /* fall back to GTT mapping */
> > + ret = -ENODEV;
> > +out_end:
> > + dma_buf_end_cpu_access(dmabuf, DMA_TO_DEVICE);
> > + return ret;
> > +}
> > +
> > static const struct drm_i915_gem_object_ops i915_gem_object_dmabuf_ops = {
> > .get_pages = i915_gem_object_get_pages_dmabuf,
> > .put_pages = i915_gem_object_put_pages_dmabuf,
> > + .pwrite = i915_gem_object_pwrite_dmabuf,
> > };
> >
> > struct drm_gem_object *i915_gem_prime_import(struct drm_device *dev,
>
>
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