Re: [PATCH 5/9] drm/i915: Clear out DPLL state from pipe config in DSI get config

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Mon, Jun 29, 2015 at 06:42:11PM +0200, Daniel Vetter wrote:
> On Mon, Jun 29, 2015 at 03:25:52PM +0300, ville.syrjala@linux.intel.com wrote:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > 
> > VLV/CHV don't use the DPLL with DSI, so just clear out the DPLL state
> > from the pipe_config in intel_dsi_get_config(). This avoids spurious
> > state checker warnings. We already did it this way for DPLL_MD, but do
> > it for DPLL too.
> > 
> > Toss in a WARN to intel_dsi_pre_enable() to make sure the ref clocks
> > are enabled however. Supposedly they have some meaning to DSI too.
> > We now keep the ref clocks always enabled while the disp2d well is
> > enabled.
> > 
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_dsi.c | 15 +++++----------
> >  1 file changed, 5 insertions(+), 10 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_dsi.c b/drivers/gpu/drm/i915/intel_dsi.c
> > index 36e2148..92bb252 100644
> > --- a/drivers/gpu/drm/i915/intel_dsi.c
> > +++ b/drivers/gpu/drm/i915/intel_dsi.c
> > @@ -421,18 +421,12 @@ static void intel_dsi_pre_enable(struct intel_encoder *encoder)
> >  
> >  	/* Disable DPOunit clock gating, can stall pipe
> >  	 * and we need DPLL REFA always enabled */
> > -	tmp = I915_READ(DPLL(pipe));
> > -	tmp |= DPLL_REF_CLK_ENABLE_VLV;
> > -	I915_WRITE(DPLL(pipe), tmp);
> > -
> > -	/* update the hw state for DPLL */
> > -	intel_crtc->config->dpll_hw_state.dpll = DPLL_INTEGRATED_REF_CLK_VLV |
> > -		DPLL_REF_CLK_ENABLE_VLV | DPLL_VGA_MODE_DIS;
> > -
> >  	tmp = I915_READ(DSPCLK_GATE_D);
> >  	tmp |= DPOUNIT_CLOCK_GATE_DISABLE;
> >  	I915_WRITE(DSPCLK_GATE_D, tmp);
> >  
> > +	WARN_ON((I915_READ(DPLL(pipe)) & DPLL_REF_CLK_ENABLE_VLV) == 0);
> > +
> >  	/* put device in ready state */
> >  	intel_dsi_device_ready(encoder);
> >  
> > @@ -635,9 +629,10 @@ static void intel_dsi_get_config(struct intel_encoder *encoder,
> >  	DRM_DEBUG_KMS("\n");
> >  
> >  	/*
> > -	 * DPLL_MD is not used in case of DSI, reading will get some default value
> > -	 * set dpll_md = 0
> > +	 * DPLL is not used in case of DSI, reading will getsome default value.
> > +	 * Clear the state to keep the state checker happy.
> >  	 */
> > +	pipe_config->dpll_hw_state.dpll = 0;
> >  	pipe_config->dpll_hw_state.dpll_md = 0;
> 
> State configs are supposed to be kzallocated. Needing this indicates a
> pretty serious bug - I'd vote to instead also ditch the dpll_md line and
> fix the offender.

There is no offender really. We read out the DPLL state before we know
which ports are active and hence can't tell at that point if the
information is really relevant.

The alternative would be to explicitly program the DPLL to a specific
state for DSI. That is, we could just call {vlv,chv}_disable_pll()
from  crtc_enable when the pipe is driving a DSI port), and have
intel_dsi_compute_config() fill in an identical state.

> -Daniel
> 
> >  
> >  	pclk = vlv_get_dsi_pclk(encoder, pipe_config->pipe_bpp);
> > -- 
> > 2.3.6
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch

-- 
Ville Syrjälä
Intel OTC
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/intel-gfx