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| author |   Jani Nikula <jani.nikula@intel.com> | 2015-12-21 15:10:52 +0200 |
|---|---|---|
| committer | Jani Nikula <jani.nikula@intel.com> | 2015-12-22 14:37:07 +0200 |
| commit | dd97950a4cb7218fac38570e2e12c57a2cfd8312 (patch) | |
| tree | fec2fe21d2a00d389439159f0c1e833449956abe /drivers/gpu/drm/i915/intel_bios.c | |
| parent | drm/i915: Unbreak check_digital_port_conflicts() (diff) | |
| download | linux-dev-dd97950a4cb7218fac38570e2e12c57a2cfd8312.tar.xz linux-dev-dd97950a4cb7218fac38570e2e12c57a2cfd8312.zip | |
drm/i915/bios: add proper documentation for the Video BIOS Table (VBT)
Add an overview and documentation for the VBT/BDB header structures.
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/3d826d4600688ca3518713776ab5bd8a8fc9f20f.1450702954.git.jani.nikula@intel.com
Diffstat (limited to 'drivers/gpu/drm/i915/intel_bios.c')
| -rw-r--r-- | drivers/gpu/drm/i915/intel_bios.c | 24 |
1 files changed, 23 insertions, 1 deletions
diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c index eba3e0f87181..b6ccba13779e 100644 --- a/drivers/gpu/drm/i915/intel_bios.c +++ b/drivers/gpu/drm/i915/intel_bios.c @@ -31,6 +31,28 @@ #include "i915_drv.h" #include "intel_bios.h" +/** + * DOC: Video BIOS Table (VBT) + * + * The Video BIOS Table, or VBT, provides platform and board specific + * configuration information to the driver that is not discoverable or available + * through other means. The configuration is mostly related to display + * hardware. The VBT is available via the ACPI OpRegion or, on older systems, in + * the PCI ROM. + * + * The VBT consists of a VBT Header (defined as &struct vbt_header), a BDB + * Header (&struct bdb_header), and a number of BIOS Data Blocks (BDB) that + * contain the actual configuration information. The VBT Header, and thus the + * VBT, begins with "$VBT" signature. The VBT Header contains the offset of the + * BDB Header. The data blocks are concatenated after the BDB Header. The data + * blocks have a 1-byte Block ID, 2-byte Block Size, and Block Size bytes of + * data. (Block 53, the MIPI Sequence Block is an exception.) + * + * The driver parses the VBT during load. The relevant information is stored in + * driver private data for ease of use, and the actual VBT is not read after + * that. + */ + #define SLAVE_ADDR1 0x70 #define SLAVE_ADDR2 0x72 @@ -1285,7 +1307,7 @@ static const struct vbt_header *find_vbt(void __iomem *bios, size_t size) /** * intel_bios_init - find VBT and initialize settings from the BIOS - * @dev: DRM device + * @dev_priv: i915 device instance * * Loads the Video BIOS and checks that the VBT exists. Sets scratch registers * to appropriate values. |