path: root/Documentation
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authorLinus Torvalds <torvalds@linux-foundation.org>2012-06-01 16:57:51 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-06-01 16:57:51 -0700
commit804ce9866d56130032c9c8afc90a1297b7deed56 (patch)
tree6dd70984f411d2a3624d3f8db7facc3d6396b9ad /Documentation
parentMerge tag 'for-linus-3.5-20120601' of git://git.infradead.org/linux-mtd (diff)
parentvideo: bfin_adv7393fb: Fix cleanup code (diff)
Merge tag 'fbdev-updates-for-3.5' of git://github.com/schandinat/linux-2.6
Pull fbdev updates from Florian Tobias Schandinat: - driver for AUO-K1900 and AUO-K1901 epaper controller - large updates for OMAP (e.g. decouple HDMI audio and video) - some updates for Exynos and SH Mobile - various other small fixes and cleanups * tag 'fbdev-updates-for-3.5' of git://github.com/schandinat/linux-2.6: (130 commits) video: bfin_adv7393fb: Fix cleanup code video: exynos_dp: reduce delay time when configuring video setting video: exynos_dp: move sw reset prioir to enabling sw defined function video: exynos_dp: use devm_ functions fb: handle NULL pointers in framebuffer release OMAPDSS: HDMI: OMAP4: Update IRQ flags for the HPD IRQ request OMAPDSS: Apply VENC timings even if panel is disabled OMAPDSS: VENC/DISPC: Delay dividing Y resolution for managers connected to VENC OMAPDSS: DISPC: Support rotation through TILER OMAPDSS: VRFB: remove compiler warnings when CONFIG_BUG=n OMAPFB: remove compiler warnings when CONFIG_BUG=n OMAPDSS: remove compiler warnings when CONFIG_BUG=n OMAPDSS: DISPC: fix usage of dispc_ovl_set_accu_uv OMAPDSS: use DSI_FIFO_BUG workaround only for manual update displays OMAPDSS: DSI: Support command mode interleaving during video mode blanking periods OMAPDSS: DISPC: Update Accumulator configuration for chroma plane drivers/video: fsl-diu-fb: don't initialize the THRESHOLDS registers video: exynos mipi dsi: support reverse panel type video: exynos mipi dsi: Properly interpret the interrupt source flags video: exynos mipi dsi: Avoid races in probe() ...
Diffstat (limited to 'Documentation')
1 files changed, 46 insertions, 0 deletions
diff --git a/Documentation/arm/OMAP/DSS b/Documentation/arm/OMAP/DSS
index 888ae7b83ae4..a564ceea9e98 100644
--- a/Documentation/arm/OMAP/DSS
+++ b/Documentation/arm/OMAP/DSS
@@ -47,6 +47,51 @@ flexible way to enable non-common multi-display configuration. In addition to
modelling the hardware overlays, omapdss supports virtual overlays and overlay
managers. These can be used when updating a display with CPU or system DMA.
+omapdss driver support for audio
+There exist several display technologies and standards that support audio as
+well. Hence, it is relevant to update the DSS device driver to provide an audio
+interface that may be used by an audio driver or any other driver interested in
+the functionality.
+The audio_enable function is intended to prepare the relevant
+IP for playback (e.g., enabling an audio FIFO, taking in/out of reset
+some IP, enabling companion chips, etc). It is intended to be called before
+audio_start. The audio_disable function performs the reverse operation and is
+intended to be called after audio_stop.
+While a given DSS device driver may support audio, it is possible that for
+certain configurations audio is not supported (e.g., an HDMI display using a
+VESA video timing). The audio_supported function is intended to query whether
+the current configuration of the display supports audio.
+The audio_config function is intended to configure all the relevant audio
+parameters of the display. In order to make the function independent of any
+specific DSS device driver, a struct omap_dss_audio is defined. Its purpose
+is to contain all the required parameters for audio configuration. At the
+moment, such structure contains pointers to IEC-60958 channel status word
+and CEA-861 audio infoframe structures. This should be enough to support
+HDMI and DisplayPort, as both are based on CEA-861 and IEC-60958.
+The audio_enable/disable, audio_config and audio_supported functions could be
+implemented as functions that may sleep. Hence, they should not be called
+while holding a spinlock or a readlock.
+The audio_start/audio_stop function is intended to effectively start/stop audio
+playback after the configuration has taken place. These functions are designed
+to be used in an atomic context. Hence, audio_start should return quickly and be
+called only after all the needed resources for audio playback (audio FIFOs,
+DMA channels, companion chips, etc) have been enabled to begin data transfers.
+audio_stop is designed to only stop the audio transfers. The resources used
+for playback are released using audio_disable.
+The enum omap_dss_audio_state may be used to help the implementations of
+the interface to keep track of the audio state. The initial state is _DISABLED;
+then, the state transitions to _CONFIGURED, and then, when it is ready to
+play audio, to _ENABLED. The state _PLAYING is used when the audio is being
Panel and controller drivers
@@ -156,6 +201,7 @@ timings Display timings (pixclock,xres/hfp/hbp/hsw,yres/vfp/vbp/vsw)
"pal" and "ntsc"
tear_elim Tearing elimination 0=off, 1=on
+output_type Output type (video encoder only): "composite" or "svideo"
There are also some debugfs files at <debugfs>/omapdss/ which show information
about clocks and registers.