Re: [PATCH 1/4] drm/i915: Use a crtc mask instead of a refcount for dpll functions.

[Ander Conselvan De Oliveira <conselvan2@gmail.com>]

On Mon, 2016-02-29 at 13:52 +0100, Maarten Lankhorst wrote:
> This makes it easier to verify correct dpll setup with only a single crtc.
> It it also useful to detect double dpll enable/disable.

I have a goal of being able to get a reference for a shared pll for an encoder
without a crtc, so that the upfront link training code doesn't need to go around
the shared pll inteface. This patch will make things a bit trickier.

I haven't yet figured out what the reference mechanism needs to be. So far I
thought about going back to ref count or including an encoder mask. But that's
for later, so see comments below.

> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/i915_debugfs.c  |  2 +-
>  drivers/gpu/drm/i915/i915_drv.h      |  2 +-
>  drivers/gpu/drm/i915/intel_display.c | 68 ++++++++++++++++++++---------------
> -
>  3 files changed, 40 insertions(+), 32 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c
> b/drivers/gpu/drm/i915/i915_debugfs.c
> index c6e64e2c951e..200e45922587 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -3211,7 +3211,7 @@ static int i915_shared_dplls_info(struct seq_file *m,
> void *unused)
>  
>  		seq_printf(m, "DPLL%i: %s, id: %i\n", i, pll->name, pll->id);
>  		seq_printf(m, " crtc_mask: 0x%08x, active: %d, on: %s\n",
> -			   pll->config.crtc_mask, pll->active, yesno(pll->on));
> +			   pll->config.crtc_mask, hweight32(pll->active_mask), 

Just print the mask as was done below and avoid hweight32?

> yesno(pll->on));
>  		seq_printf(m, " tracked hardware state:\n");
>  		seq_printf(m, " dpll:    0x%08x\n", pll
> ->config.hw_state.dpll);
>  		seq_printf(m, " dpll_md: 0x%08x\n",
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 10480939159c..c7401b50818c 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -392,7 +392,7 @@ struct intel_shared_dpll_config {
>  struct intel_shared_dpll {
>  	struct intel_shared_dpll_config config;
>  
> -	int active; /* count of number of active CRTCs (i.e. DPMS on) */
> +	unsigned active_mask; /* mask of active CRTCs (i.e. DPMS on) */
>  	bool on; /* is the PLL actually active? Disabled during modeset */
>  	const char *name;
>  	/* should match the index in the dev_priv->shared_dplls array */
> diff --git a/drivers/gpu/drm/i915/intel_display.c
> b/drivers/gpu/drm/i915/intel_display.c
> index a5d61084ae98..5dd59cae9f06 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -1866,7 +1866,7 @@ static void intel_prepare_shared_dpll(struct intel_crtc
> *crtc)
>  		return;
>  
>  	WARN_ON(!pll->config.crtc_mask);
> -	if (pll->active == 0) {
> +	if (pll->active_mask == 0) {
>  		DRM_DEBUG_DRIVER("setting up %s\n", pll->name);
>  		WARN_ON(pll->on);
>  		assert_shared_dpll_disabled(dev_priv, pll);
> @@ -1888,6 +1888,7 @@ static void intel_enable_shared_dpll(struct intel_crtc
> *crtc)
>  	struct drm_device *dev = crtc->base.dev;
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  	struct intel_shared_dpll *pll = intel_crtc_to_shared_dpll(crtc);
> +	unsigned crtc_mask = 1 << drm_crtc_index(&crtc->base);
>  
>  	if (WARN_ON(pll == NULL))
>  		return;
> @@ -1895,11 +1896,16 @@ static void intel_enable_shared_dpll(struct intel_crtc
> *crtc)
>  	if (WARN_ON(pll->config.crtc_mask == 0))
>  		return;
>  
> +	if (WARN_ON(pll->active_mask & crtc_mask))
> +		return;
> +
>  	DRM_DEBUG_KMS("enable %s (active %d, on? %d) for crtc %d\n",
> -		      pll->name, pll->active, pll->on,
> +		      pll->name, hweight32(pll->active_mask), pll->on,
>  		      crtc->base.base.id);
>  
> -	if (pll->active++) {
> +	pll->active_mask |= crtc_mask;
> +
> +	if (pll->active_mask != crtc_mask) {
>  		WARN_ON(!pll->on);
>  		assert_shared_dpll_enabled(dev_priv, pll);
>  		return;
> @@ -1918,30 +1924,33 @@ static void intel_disable_shared_dpll(struct
> intel_crtc *crtc)
>  	struct drm_device *dev = crtc->base.dev;
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  	struct intel_shared_dpll *pll = intel_crtc_to_shared_dpll(crtc);
> +	unsigned crtc_mask = 1 << drm_crtc_index(&crtc->base);
>  
>  	/* PCH only available on ILK+ */
> -	if (INTEL_INFO(dev)->gen < 5)
> +	if (INTEL_INFO(dev_priv)->gen < 5)
>  		return;
>  
>  	if (pll == NULL)
>  		return;
>  
> -	if (WARN_ON(!(pll->config.crtc_mask & (1 << drm_crtc_index(&crtc
> ->base)))))
> +	if (WARN_ON(!(pll->config.crtc_mask & crtc_mask)))
>  		return;
>  
> -	DRM_DEBUG_KMS("disable %s (active %d, on? %d) for crtc %d\n",
> -		      pll->name, pll->active, pll->on,
> +	if (WARN_ON(!(pll->active_mask & crtc_mask)))
> +		return;
> +
> +	DRM_DEBUG_KMS("disable %s (active %x, on? %d) for crtc %d\n",
> +		      pll->name, pll->active_mask, pll->on,
>  		      crtc->base.base.id);
>  
> -	if (WARN_ON(pll->active == 0)) {
> +	pll->active_mask &= ~crtc_mask;
> +	if (pll->active_mask) {
>  		assert_shared_dpll_disabled(dev_priv, pll);

Shouldn't the above be changed to assert enabled, as the pll is still active for
another crtc?

>  		return;
>  	}
>  
>  	assert_shared_dpll_enabled(dev_priv, pll);
>  	WARN_ON(!pll->on);
> -	if (--pll->active)
> -		return;
>  
>  	DRM_DEBUG_KMS("disabling %s\n", pll->name);
>  	pll->disable(dev_priv, pll);
> @@ -4294,10 +4303,10 @@ struct intel_shared_dpll *intel_get_shared_dpll(struct
> intel_crtc *crtc,
>  		if (memcmp(&crtc_state->dpll_hw_state,
>  			   &shared_dpll[i].hw_state,
>  			   sizeof(crtc_state->dpll_hw_state)) == 0) {
> -			DRM_DEBUG_KMS("CRTC:%d sharing existing %s (crtc mask
> 0x%08x, ative %d)\n",
> +			DRM_DEBUG_KMS("CRTC:%d sharing existing %s (crtc mask
> 0x%08x, active 0x%08x)\n",
>  				      crtc->base.base.id, pll->name,
>  				      shared_dpll[i].crtc_mask,
> -				      pll->active);
> +				      pll->active_mask);
>  			goto found;
>  		}
>  	}
> @@ -12952,12 +12961,12 @@ check_shared_dpll_state(struct drm_device *dev)
>  
>  		active = pll->get_hw_state(dev_priv, pll, &dpll_hw_state);
>  
> -		I915_STATE_WARN(pll->active > hweight32(pll
> ->config.crtc_mask),
> -		     "more active pll users than references: %i vs %i\n",
> -		     pll->active, hweight32(pll->config.crtc_mask));
> -		I915_STATE_WARN(pll->active && !pll->on,
> +		I915_STATE_WARN(pll->active_mask & ~pll->config.crtc_mask,
> +		     "more active pll users than references: %x vs %x\n",
> +		     pll->active_mask, pll->config.crtc_mask);
> +		I915_STATE_WARN(pll->active_mask && !pll->on,
>  		     "pll in active use but not on in sw tracking\n");
> -		I915_STATE_WARN(pll->on && !pll->active,
> +		I915_STATE_WARN(pll->on && !pll->active_mask,
>  		     "pll in on but not on in use in sw tracking\n");
>  		I915_STATE_WARN(pll->on != active,
>  		     "pll on state mismatch (expected %i, found %i)\n",
> @@ -12965,16 +12974,16 @@ check_shared_dpll_state(struct drm_device *dev)
>  
>  		for_each_intel_crtc(dev, crtc) {
>  			if (crtc->base.state->enable &&
> intel_crtc_to_shared_dpll(crtc) == pll)
> -				enabled_crtcs++;
> +				enabled_crtcs |= 1 << drm_crtc_index(&crtc
> ->base);
>  			if (crtc->active && intel_crtc_to_shared_dpll(crtc)
> == pll)
> -				active_crtcs++;
> +				active_crtcs |= 1 << drm_crtc_index(&crtc
> ->base);

Maybe change the type of active_crtcs and enabled_crtcs to unsigned, as they are
being used as masks.

With the above addressed,

Reviewed-by: Ander Conselvan de Oliveira <conselvan2@gmail.com>


>  		}
> -		I915_STATE_WARN(pll->active != active_crtcs,
> -		     "pll active crtcs mismatch (expected %i, found %i)\n",
> -		     pll->active, active_crtcs);
> -		I915_STATE_WARN(hweight32(pll->config.crtc_mask) !=
> enabled_crtcs,
> -		     "pll enabled crtcs mismatch (expected %i, found %i)\n",
> -		     hweight32(pll->config.crtc_mask), enabled_crtcs);
> +		I915_STATE_WARN(pll->active_mask != active_crtcs,
> +		     "pll active crtcs mismatch (expected %x, found %x)\n",
> +		     pll->active_mask, active_crtcs);
> +		I915_STATE_WARN(pll->config.crtc_mask != enabled_crtcs,
> +		     "pll enabled crtcs mismatch (expected %x, found %x)\n",
> +		     pll->config.crtc_mask, enabled_crtcs);
>  
>  		I915_STATE_WARN(pll->on && memcmp(&pll->config.hw_state,
> &dpll_hw_state,
>  				       sizeof(dpll_hw_state)),
> @@ -15760,14 +15769,13 @@ static void intel_modeset_readout_hw_state(struct
> drm_device *dev)
>  
>  		pll->on = pll->get_hw_state(dev_priv, pll,
>  					    &pll->config.hw_state);
> -		pll->active = 0;
> +		pll->active_mask = 0;
>  		pll->config.crtc_mask = 0;
>  		for_each_intel_crtc(dev, crtc) {
> -			if (crtc->active && intel_crtc_to_shared_dpll(crtc)
> == pll) {
> -				pll->active++;
> +			if (crtc->active && intel_crtc_to_shared_dpll(crtc)
> == pll)
>  				pll->config.crtc_mask |= 1 << crtc->pipe;
> -			}
>  		}
> +		pll->active_mask = pll->config.crtc_mask;
>  
>  		DRM_DEBUG_KMS("%s hw state readout: crtc_mask 0x%08x, on
> %i\n",
>  			      pll->name, pll->config.crtc_mask, pll->on);
> @@ -15889,7 +15897,7 @@ intel_modeset_setup_hw_state(struct drm_device *dev)
>  	for (i = 0; i < dev_priv->num_shared_dpll; i++) {
>  		struct intel_shared_dpll *pll = &dev_priv->shared_dplls[i];
>  
> -		if (!pll->on || pll->active)
> +		if (!pll->on || pll->active_mask)
>  			continue;
>  
>  		DRM_DEBUG_KMS("%s enabled but not in use, disabling\n", pll
> ->name);
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