Re: [Intel-gfx] [PATCH v2] drm/i915: dell wyse 3040 shutdown fix

[Alexey Lukyachuk]

On Tue, 27 Dec 2022 11:39:25 -0500
Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx> wrote:

> On Sun, Dec 25, 2022 at 09:55:08PM +0300, Alexey Lukyanchuk wrote:
> > dell wyse 3040 doesn't peform poweroff properly, but instead remains in 
> > turned power on state.
> 
> okay, the motivation is explained in the commit msg..
> 
> > Additional mutex_lock and 
> > intel_crtc_wait_for_next_vblank 
> > feature 6.2 kernel resolve this trouble.
> 
> but this why is not very clear... seems that by magic it was found,
> without explaining what race we are really protecting here.
> 
> but even worse is:
> what about those many random vblank waits in the code? what's the
> reasoning?
> 
> > 
> > cc: stable@xxxxxxxxxxxxxxx
> > original commit Link: https://patchwork.freedesktop.org/patch/508926/
> > fixes: fe0f1e3bfdfeb53e18f1206aea4f40b9bd1f291c
> > Signed-off-by: Alexey Lukyanchuk <skif@xxxxxxxxxxx>
> > ---
> > I got some troubles with this device (dell wyse 3040) since kernel 5.11
> > started to use i915_driver_shutdown function. I found solution here:
> > 
> > https://lore.kernel.org/dri-devel/Y1wd6ZJ8LdJpCfZL@xxxxxxxxx/#r
> > 
> > ---
> >  drivers/gpu/drm/i915/display/intel_audio.c | 37 +++++++++++++++-------
> >  1 file changed, 25 insertions(+), 12 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_audio.c b/drivers/gpu/drm/i915/display/intel_audio.c
> > index aacbc6da8..44344ecdf 100644
> > --- a/drivers/gpu/drm/i915/display/intel_audio.c
> > +++ b/drivers/gpu/drm/i915/display/intel_audio.c
> > @@ -336,6 +336,7 @@ static void g4x_audio_codec_disable(struct intel_encoder *encoder,
> >  				    const struct drm_connector_state *old_conn_state)
> >  {
> >  	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> > +	struct intel_crtc *crtc = to_intel_crtc(old_crtc_state->uapi.crtc);
> >  	u32 eldv, tmp;
> >  
> >  	tmp = intel_de_read(dev_priv, G4X_AUD_VID_DID);
> > @@ -348,6 +349,9 @@ static void g4x_audio_codec_disable(struct intel_encoder *encoder,
> >  	tmp = intel_de_read(dev_priv, G4X_AUD_CNTL_ST);
> >  	tmp &= ~eldv;
> >  	intel_de_write(dev_priv, G4X_AUD_CNTL_ST, tmp);
> > +
> > +	intel_crtc_wait_for_next_vblank(crtc);
> > +	intel_crtc_wait_for_next_vblank(crtc);
> >  }
> >  
> >  static void g4x_audio_codec_enable(struct intel_encoder *encoder,
> > @@ -355,12 +359,15 @@ static void g4x_audio_codec_enable(struct intel_encoder *encoder,
> >  				   const struct drm_connector_state *conn_state)
> >  {
> >  	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> > +	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
> >  	struct drm_connector *connector = conn_state->connector;
> >  	const u8 *eld = connector->eld;
> >  	u32 eldv;
> >  	u32 tmp;
> >  	int len, i;
> >  
> > +	intel_crtc_wait_for_next_vblank(crtc);
> > +
> >  	tmp = intel_de_read(dev_priv, G4X_AUD_VID_DID);
> >  	if (tmp == INTEL_AUDIO_DEVBLC || tmp == INTEL_AUDIO_DEVCL)
> >  		eldv = G4X_ELDV_DEVCL_DEVBLC;
> > @@ -493,6 +500,7 @@ static void hsw_audio_codec_disable(struct intel_encoder *encoder,
> >  				    const struct drm_connector_state *old_conn_state)
> >  {
> >  	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> > +	struct intel_crtc *crtc = to_intel_crtc(old_crtc_state->uapi.crtc);
> >  	enum transcoder cpu_transcoder = old_crtc_state->cpu_transcoder;
> >  	u32 tmp;
> >  
> > @@ -508,6 +516,10 @@ static void hsw_audio_codec_disable(struct intel_encoder *encoder,
> >  		tmp |= AUD_CONFIG_N_VALUE_INDEX;
> >  	intel_de_write(dev_priv, HSW_AUD_CFG(cpu_transcoder), tmp);
> >  
> > +
> > +	intel_crtc_wait_for_next_vblank(crtc);
> > +	intel_crtc_wait_for_next_vblank(crtc);
> > +
> >  	/* Invalidate ELD */
> >  	tmp = intel_de_read(dev_priv, HSW_AUD_PIN_ELD_CP_VLD);
> >  	tmp &= ~AUDIO_ELD_VALID(cpu_transcoder);
> > @@ -633,6 +645,7 @@ static void hsw_audio_codec_enable(struct intel_encoder *encoder,
> >  				   const struct drm_connector_state *conn_state)
> >  {
> >  	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> > +	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
> >  	struct drm_connector *connector = conn_state->connector;
> >  	enum transcoder cpu_transcoder = crtc_state->cpu_transcoder;
> >  	const u8 *eld = connector->eld;
> > @@ -651,12 +664,7 @@ static void hsw_audio_codec_enable(struct intel_encoder *encoder,
> >  	tmp &= ~AUDIO_ELD_VALID(cpu_transcoder);
> >  	intel_de_write(dev_priv, HSW_AUD_PIN_ELD_CP_VLD, tmp);
> >  
> > -	/*
> > -	 * FIXME: We're supposed to wait for vblank here, but we have vblanks
> > -	 * disabled during the mode set. The proper fix would be to push the
> > -	 * rest of the setup into a vblank work item, queued here, but the
> > -	 * infrastructure is not there yet.
> > -	 */
> > +	intel_crtc_wait_for_next_vblank(crtc);
> >  
> >  	/* Reset ELD write address */
> >  	tmp = intel_de_read(dev_priv, HSW_AUD_DIP_ELD_CTRL(cpu_transcoder));
> > @@ -705,6 +713,8 @@ static void ilk_audio_codec_disable(struct intel_encoder *encoder,
> >  		aud_cntrl_st2 = CPT_AUD_CNTRL_ST2;
> >  	}
> >  
> > +	mutex_lock(&dev_priv->display.audio.mutex);
> > +
> >  	/* Disable timestamps */
> >  	tmp = intel_de_read(dev_priv, aud_config);
> >  	tmp &= ~AUD_CONFIG_N_VALUE_INDEX;
> > @@ -721,6 +731,10 @@ static void ilk_audio_codec_disable(struct intel_encoder *encoder,
> >  	tmp = intel_de_read(dev_priv, aud_cntrl_st2);
> >  	tmp &= ~eldv;
> >  	intel_de_write(dev_priv, aud_cntrl_st2, tmp);
> > +	mutex_unlock(&dev_priv->display.audio.mutex);
> > +
> > +	intel_crtc_wait_for_next_vblank(crtc);
> > +	intel_crtc_wait_for_next_vblank(crtc);
> >  }
> >  
> >  static void ilk_audio_codec_enable(struct intel_encoder *encoder,
> > @@ -740,12 +754,7 @@ static void ilk_audio_codec_enable(struct intel_encoder *encoder,
> >  	if (drm_WARN_ON(&dev_priv->drm, port == PORT_A))
> >  		return;
> >  
> > -	/*
> > -	 * FIXME: We're supposed to wait for vblank here, but we have vblanks
> > -	 * disabled during the mode set. The proper fix would be to push the
> > -	 * rest of the setup into a vblank work item, queued here, but the
> > -	 * infrastructure is not there yet.
> > -	 */
> > +	intel_crtc_wait_for_next_vblank(crtc);
> >  
> >  	if (HAS_PCH_IBX(dev_priv)) {
> >  		hdmiw_hdmiedid = IBX_HDMIW_HDMIEDID(pipe);
> > @@ -767,6 +776,8 @@ static void ilk_audio_codec_enable(struct intel_encoder *encoder,
> >  
> >  	eldv = IBX_ELD_VALID(port);
> >  
> > +	mutex_lock(&dev_priv->display.audio.mutex);
> > +
> >  	/* Invalidate ELD */
> >  	tmp = intel_de_read(dev_priv, aud_cntrl_st2);
> >  	tmp &= ~eldv;
> > @@ -798,6 +809,8 @@ static void ilk_audio_codec_enable(struct intel_encoder *encoder,
> >  	else
> >  		tmp |= audio_config_hdmi_pixel_clock(crtc_state);
> >  	intel_de_write(dev_priv, aud_config, tmp);
> > +
> > +	mutex_unlock(&dev_priv->display.audio.mutex);
> >  }
> >  
> >  /**
> > -- 
> > 2.25.1
> > 


I would like to say, that this solution was found in drm-tip repository:
link: git://anongit.freedesktop.org/drm-tip
I will quotate original commit message from Ville Syrjälä 
<ville.syrjala@xxxxxxxxxxxxxxx>: "The spec tells us to do a bunch of 
vblank waits in the audio enable/disable sequences. Make it so."
So it's just a backport of accepted patch.
Which i wanna to propagate to stable versions