From 9db13e5f2d6dc85150cb8a69ab220b84d9b9fbe7 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Thu, 2 Feb 2017 11:03:48 +0100 Subject: drm/i915: Enable VLV audio chicken bit for LPE audio MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The audio chicken bit (register offset 0x62f38) seems required to make DP audio working on some machines. At least, on Dell Wyse 3040, I failed to get the audio unless this bit is set once. Strangely, the bit seems necessary only once, and it persists after that, even some power-off cycles. The register is supposedly write-only, so it's no evidence whether the bit keeps effect persistently. But, judging from the experiment, it looks enough to set it up once at the device initialization. The patch is basically a cut from the original patch by Pierre-Louis Bossart. v1->v2: drop read since it's a write-only reg. Cc: Pierre-Louis Bossart Reviewed-by: Ville Syrjälä Signed-off-by: Takashi Iwai --- drivers/gpu/drm/i915/intel_lpe_audio.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'drivers/gpu/drm/i915/intel_lpe_audio.c') diff --git a/drivers/gpu/drm/i915/intel_lpe_audio.c b/drivers/gpu/drm/i915/intel_lpe_audio.c index d3ffe00..7a5b41b 100644 --- a/drivers/gpu/drm/i915/intel_lpe_audio.c +++ b/drivers/gpu/drm/i915/intel_lpe_audio.c @@ -248,6 +248,11 @@ static int lpe_audio_setup(struct drm_i915_private *dev_priv) goto err_free_irq; } + /* enable chicken bit; at least this is required for Dell Wyse 3040 + * with DP outputs (but only sometimes by some reason!) + */ + I915_WRITE(VLV_AUD_CHICKEN_BIT_REG, VLV_CHICKEN_BIT_DBG_ENABLE); + return 0; err_free_irq: irq_free_desc(dev_priv->lpe_audio.irq); -- cgit v1.1