drm/i915: Iterate over pipes and skip the disabled one

It should not be assumed that a disabled display pipe will be
always last the pipe.
for_each_pipe() should iterate over I915_MAX_PIPES and check
for the disabled pipe and skip that pipe so that it should not
initialize the intel crtc for any disabled pipes.

Due to changes in for_each_pipe() macro, it requires to handle
the below compilation error.
"suggest explicit braces to avoid ambiguous ‘else’
[-Werror=dangling-else]"

v2:
- Cosmetic changes, removed unwanted parentheses. [Ville]

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200224124004.26712-2-anshuman.gupta@intel.com

drivers/gpu/drm/i915/display/intel_display.h

@@ -313,10 +313,11 @@ enum phy_fia {
 };
 
 #define for_each_pipe(__dev_priv, __p) \
-	for ((__p) = 0; (__p) < INTEL_NUM_PIPES(__dev_priv); (__p)++)
+	for ((__p) = 0; (__p) < I915_MAX_PIPES; (__p)++) \
+		for_each_if(INTEL_INFO(__dev_priv)->pipe_mask & BIT(__p))
 
 #define for_each_pipe_masked(__dev_priv, __p, __mask) \
-	for ((__p) = 0; (__p) < INTEL_NUM_PIPES(__dev_priv); (__p)++) \
+	for_each_pipe(__dev_priv, __p) \
 		for_each_if((__mask) & BIT(__p))
 
 #define for_each_cpu_transcoder_masked(__dev_priv, __t, __mask) \

drivers/gpu/drm/i915/i915_irq.c

@@ -1739,11 +1739,12 @@ static void ibx_irq_handler(struct drm_i915_private *dev_priv, u32 pch_iir)
 	if (pch_iir & SDE_POISON)
 		drm_err(&dev_priv->drm, "PCH poison interrupt\n");
 
-	if (pch_iir & SDE_FDI_MASK)
+	if (pch_iir & SDE_FDI_MASK) {
 		for_each_pipe(dev_priv, pipe)
 			drm_dbg(&dev_priv->drm, "  pipe %c FDI IIR: 0x%08x\n",
 				pipe_name(pipe),
 				I915_READ(FDI_RX_IIR(pipe)));
+	}
 
 	if (pch_iir & (SDE_TRANSB_CRC_DONE | SDE_TRANSA_CRC_DONE))
 		drm_dbg(&dev_priv->drm, "PCH transcoder CRC done interrupt\n");
@@ -1823,11 +1824,12 @@ static void cpt_irq_handler(struct drm_i915_private *dev_priv, u32 pch_iir)
 	if (pch_iir & SDE_AUDIO_CP_CHG_CPT)
 		drm_dbg(&dev_priv->drm, "Audio CP change interrupt\n");
 
-	if (pch_iir & SDE_FDI_MASK_CPT)
+	if (pch_iir & SDE_FDI_MASK_CPT) {
 		for_each_pipe(dev_priv, pipe)
 			drm_dbg(&dev_priv->drm, "  pipe %c FDI IIR: 0x%08x\n",
 				pipe_name(pipe),
 				I915_READ(FDI_RX_IIR(pipe)));
+	}
 
 	if (pch_iir & SDE_ERROR_CPT)
 		cpt_serr_int_handler(dev_priv);