On Sat, Jun 29, 2013 at 11:53:22PM +0100, Russell King wrote:
> This patch adds support for the pair of LCD controllers on the Marvell
> Armada 510 SoCs. This driver supports:
> - multiple contiguous scanout buffers for video and graphics
> - shm backed cacheable buffer objects for X pixmaps for Vivante GPU
> acceleration
> - dual lcd0 and lcd1 crt operation
> - video overlay on each LCD crt
> - page flipping of the main scanout buffers
>
> Included in this commit is the core driver with no output support; output
> support is platform and encoder driver dependent.
>
> Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
Found one more ...
[snip]
> +int
> +armada_gem_linear_back(struct drm_device *dev, struct armada_gem_object *obj)
> +{
> + struct armada_private *priv = dev->dev_private;
> + size_t size = obj->obj.size;
> +
> + if (obj->page || obj->linear)
> + return 0;
> +
> + /*
> + * If it is a small allocation (typically cursor, which will
> + * be 32x64 or 64x32 ARGB pixels) try to get it from the system.
> + * Framebuffers will never be this small (our minimum size for
> + * framebuffers is larger than this anyway.) Such objects are
> + * only accessed by the CPU so we don't need any special handing
> + * here.
> + */
> + if (size <= 8192) {
> + unsigned int order = get_order(size);
> + struct page *p = alloc_pages(GFP_KERNEL, order);
> +
> + if (p) {
> + obj->addr = page_address(p);
> + obj->phys_addr = page_to_phys(p);
> + obj->page = p;
> +
> + memset(obj->addr, 0, PAGE_ALIGN(size));
> + }
> + }
> +
> + /*
> + * We could grab something from CMA if it's enabled, but that
> + * involves building in a problem:
> + *
> + * CMA's interface uses dma_alloc_coherent(), which provides us
> + * with an CPU virtual address and a device address.
> + *
> + * The CPU virtual address may be either an address in the kernel
> + * direct mapped region (for example, as it would be on x86) or
> + * it may be remapped into another part of kernel memory space
> + * (eg, as it would be on ARM.) This means virt_to_phys() on the
> + * returned virtual address is invalid depending on the architecture
> + * implementation.
> + *
> + * The device address may also not be a physical address; it may
> + * be that there is some kind of remapping between the device and
> + * system RAM, which makes the use of the device address also
> + * unsafe to re-use as a physical address.
> + *
> + * This makes DRM usage of dma_alloc_coherent() in a generic way
> + * at best very questionable and unsafe.
> + */
> +
> + /* Otherwise, grab it from our linear allocation */
> + if (!obj->page) {
> + struct drm_mm_node *free;
> + unsigned align = min_t(unsigned, size, SZ_2M);
> + void __iomem *ptr;
> +
> + mutex_lock(&dev->struct_mutex);
> + free = drm_mm_search_free(&priv->linear, size, align, 0);
> + if (free)
> + obj->linear = drm_mm_get_block(free, size, align);
> + mutex_unlock(&dev->struct_mutex);
The two-stage search_free+get_block drm_mm interface is something I'd like
to remove since it' complicates the interface for no gain. And the
preallocation trick for atomic contexts is pretty racy as-is. Can you
please convert this over to the insert_node interfaces which take a
preallocate drm_mm_node?
Thanks, Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
