On Wed, Jun 11, 2014 at 10:43:30AM -0700, Stéphane Marchesin wrote:
On Tue, Jun 10, 2014 at 4:04 AM, Thierry Reding thierry.reding@gmail.com wrote:
From: Thierry Reding treding@nvidia.com
Currently the tiling parameters of buffer objects can only be set at allocation time, and only a single tiled mode is supported. This new DRM_TEGRA_GEM_SET_TILING IOCTL allows more modes to be set and also allows the tiling mode to be changed after the allocation. This will enable the Tegra DRM driver to import buffers from a GPU and directly scan them out by configuring the display controller appropriately.
I was wondering why not support the new tiling modes on creation as well, I guess because you don't have room for height in the creation ioctl?
Yes, back at the time when the GEM_CREATE IOCTL was added we only left enough room for "flags", so it'll be difficult to add support for the newer tiling modes.
One possibility that I see is to extend struct drm_tegra_gem_create in a backwards-compatible way and make new fields dependent on some new flag, somewhat like this:
#define DRM_TEGRA_GEM_CREATE_BLOCK_LINEAR (1 << 3)
struct drm_tegra_gem_create { __u64 size; __u32 flags; __u32 handle; __u32 height; __u32 pad; };
Then the DRM driver can parse the height field only if the BLOCK_LINEAR flag is set.
To be honest, though, I'd prefer to deprecate the flags at creation if these patches get merged so that we can have a standard way of setting these rather than a few.
Do you see any particular advantages in specifying the tiling mode at creation time?
diff --git a/include/uapi/drm/tegra_drm.h b/include/uapi/drm/tegra_drm.h index b75482112428..0829f75eb986 100644 --- a/include/uapi/drm/tegra_drm.h +++ b/include/uapi/drm/tegra_drm.h @@ -129,6 +129,27 @@ struct drm_tegra_submit { __u32 reserved[5]; /* future expansion */ };
+#define DRM_TEGRA_GEM_TILING_MODE_PITCH 0 +#define DRM_TEGRA_GEM_TILING_MODE_TILED 1 +#define DRM_TEGRA_GEM_TILING_MODE_BLOCK 2
+struct drm_tegra_gem_set_tiling {
/* input */__u32 handle;__u32 mode;__u32 value;This seems to only be used for height, if so should it be called height?
The idea here was to have a generic name here so that it could be more easily extended if/when newer tiling modes are introduced.
Thierry