drm/i915: Delay allocation of stolen space for FBC
As FBC is commonly disabled due to limitations of the chipset upon
output configurations, on many systems FBC is never enabled. For those
systems, it is advantageous to make use of the stolen memory for other
objects and so we defer allocation of the FBC chunk until we actually
require it. This increases the likelihood of that allocation failing,
but that in turns means that we are already taking advantage of the
stolen memory!
As well as delaying the allocation from driver initialisation until the
first use of FBC, we also return the stolen block after we finish using
it - allowing greater flexibility in our usage of stolen space. A side
effect of this is that we can then attempt to allocate only the required
amount of space (with a little slack to reduce reallocation rate and
avoid fragmentation).
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index f595b8d..abfff29 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -440,12 +440,6 @@
dev_priv->no_fbc_reason = FBC_MODULE_PARAM;
goto out_disable;
}
- if (intel_fb->obj->base.size > dev_priv->cfb_size) {
- DRM_DEBUG_KMS("framebuffer too large, disabling "
- "compression\n");
- dev_priv->no_fbc_reason = FBC_STOLEN_TOO_SMALL;
- goto out_disable;
- }
if ((crtc->mode.flags & DRM_MODE_FLAG_INTERLACE) ||
(crtc->mode.flags & DRM_MODE_FLAG_DBLSCAN)) {
DRM_DEBUG_KMS("mode incompatible with compression, "
@@ -479,6 +473,14 @@
if (in_dbg_master())
goto out_disable;
+ if (i915_gem_stolen_setup_compression(dev, intel_fb->obj->base.size)) {
+ DRM_INFO("not enough stolen space for compressed buffer (need %zd bytes), disabling\n", intel_fb->obj->base.size);
+ DRM_INFO("hint: you may be able to increase stolen memory size in the BIOS to avoid this\n");
+ DRM_DEBUG_KMS("framebuffer too large, disabling compression\n");
+ dev_priv->no_fbc_reason = FBC_STOLEN_TOO_SMALL;
+ goto out_disable;
+ }
+
/* If the scanout has not changed, don't modify the FBC settings.
* Note that we make the fundamental assumption that the fb->obj
* cannot be unpinned (and have its GTT offset and fence revoked)
@@ -526,6 +528,7 @@
DRM_DEBUG_KMS("unsupported config, disabling FBC\n");
intel_disable_fbc(dev);
}
+ i915_gem_stolen_cleanup_compression(dev);
}
static void i915_pineview_get_mem_freq(struct drm_device *dev)