On Tue, Aug 16, 2016 at 9:38 PM, Noralf Trønnes <noralf@xxxxxxxxxxx> wrote: >> That's still a lot for what amounts to reimplementing mmap on shmem, but >> badly. What I mean with redirecting is pointing the entire ->mmap >> operation to the mmap implementation for the underlying mmap. Roughly: >> >> /* normal gem mmap checks first */ >> >> /* redirect to shmem mmap */ >> vma->vm_file = obj->filp; >> vma->vm_pgoff = 0; >> >> return obj->filp->f_op->mmap(obj->filp, vma); >> >> Much less code ;-) > > > obj->filp is NULL in my case. > > And looking at the docs, that's expected since I have driver specific > backing? > > /** > * @filp: > * > * SHMEM file node used as backing storage for swappable buffer objects. > * GEM also supports driver private objects with driver-specific backing > * storage (contiguous CMA memory, special reserved blocks). In this > * case @filp is NULL. > */ Hm, I totally misread the driver code. I assumed that we'd just allocate normal shmem gem objects, and then copy them on-demand onto the frontbuffer (in the dirty or plane update callbacks). Essentially treat the firmware fb area as a manual upload display, except that we don't use i2c or spi to do the upload, but normal mmio writes. I think that would greatly simplify the driver, and more important: It would also work like any other kms driver. Currently sdrm is violiting the spec a bit by aliasing all dumb buffers to the same underlying backing storage, and that's a bit evil. The other bit I noticed (and why I was confused): The prime import code reinvents a lot of wheels, and it digs into the backing storage directly. Instead it should just call dma_buf_vmap/dma_buf_vunmap and let the exporter figure out how it works. Sorry I was all confused here and didn't realize what's going on :( -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
