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authorRussell King <rmk+kernel@arm.linux.org.uk>2015-03-27 12:59:58 +0000
committerRussell King <rmk+kernel@arm.linux.org.uk>2015-08-18 11:27:15 +0100
commitb90120a9660884b8f11bbb9904fbaa4c12d17e0a (patch)
tree087e1dd7e19fd285200754bbbcc51886030d3761 /include/drm
parentb5814fff27c6d0212b86306bdd01fe3aea99cabb (diff)
downloadlinux-linaro-stable-b90120a9660884b8f11bbb9904fbaa4c12d17e0a.tar.gz
drm: bridge/dw_hdmi: introduce interfaces to enable and disable audio
iMX6 devices suffer from an errata (ERR005174) where the audio FIFO can be emptied while it is partially full, resulting in misalignment of the audio samples. To prevent this, the errata workaround recommends writing N as zero until the audio FIFO has been loaded by DMA. Writing N=0 prevents the HDMI bridge from reading from the audio FIFO, effectively disabling audio. This means we need to provide the audio driver with a pair of functions to enable/disable audio. These are dw_hdmi_audio_enable() and dw_hdmi_audio_disable(). A spinlock is introduced to ensure that setting the CTS/N values can't race, ensuring that the audio driver calling the enable/disable functions (which are called in an atomic context) can't race with a modeset. Tested-by: Yakir Yang <ykk@rock-chips.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'include/drm')
-rw-r--r--include/drm/bridge/dw_hdmi.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/drm/bridge/dw_hdmi.h b/include/drm/bridge/dw_hdmi.h
index 763af51e1d60..bae79f3c4d28 100644
--- a/include/drm/bridge/dw_hdmi.h
+++ b/include/drm/bridge/dw_hdmi.h
@@ -63,5 +63,7 @@ int dw_hdmi_bind(struct device *dev, struct device *master,
const struct dw_hdmi_plat_data *plat_data);
void dw_hdmi_set_sample_rate(struct dw_hdmi *hdmi, unsigned int rate);
+void dw_hdmi_audio_enable(struct dw_hdmi *hdmi);
+void dw_hdmi_audio_disable(struct dw_hdmi *hdmi);
#endif /* __IMX_HDMI_H__ */