Re: [PATCH 06/18] drm/i915: Delay allocation of stolen space for FBC

Ben Widawsky
2012-11-05T13:43:48Z

On Fri, 19 Oct 2012 18:03:12 +0100
Chris Wilson <chris@chris-wilson.co.uk> wrote:

> As we may wish to wrap regions preallocated by the BIOS, we need to do
> that before carving out contiguous chunks of stolen space for FBC.
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>

More nitckicks:
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>

> ---
> drivers/gpu/drm/i915/i915_drv.h | 2 +
> drivers/gpu/drm/i915/i915_gem_stolen.c | 115 ++++++++++++++++----------------
> drivers/gpu/drm/i915/intel_display.c | 3 +
> drivers/gpu/drm/i915/intel_pm.c | 3 +-
> 4 files changed, 66 insertions(+), 57 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 589b2f3..997abb3 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1516,6 +1516,8 @@ int i915_gem_evict_everything(struct drm_device *dev);
>
> /* i915_gem_stolen.c */
> int i915_gem_init_stolen(struct drm_device *dev);
> +int i915_gem_stolen_setup_compression(struct drm_device *dev);
> +void i915_gem_stolen_cleanup_compression(struct drm_device *dev);
> void i915_gem_cleanup_stolen(struct drm_device *dev);
>
> /* i915_gem_tiling.c */
> diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c b/drivers/gpu/drm/i915/i915_gem_stolen.c
> index d023ed6..68ef22a 100644
> --- a/drivers/gpu/drm/i915/i915_gem_stolen.c
> +++ b/drivers/gpu/drm/i915/i915_gem_stolen.c
> @@ -89,21 +89,13 @@ static unsigned long i915_stolen_to_physical(struct drm_device *dev)
> return base;
> }
>
> -static void i915_warn_stolen(struct drm_device *dev)
> -{
> - DRM_INFO("not enough stolen space for compressed buffer, disabling\n");
> - DRM_INFO("hint: you may be able to increase stolen memory size in the BIOS to avoid this\n");
> -}
> -
> -static void i915_setup_compression(struct drm_device *dev, int size)
> +static int i915_setup_compression(struct drm_device *dev, int size)
> {
> struct drm_i915_private *dev_priv = dev->dev_private;
> struct drm_mm_node *compressed_fb, *uninitialized_var(compressed_llb);
> - unsigned long cfb_base;
> - unsigned long ll_base = 0;
>
> - /* Just in case the BIOS is doing something questionable. */
> - intel_disable_fbc(dev);
> + DRM_DEBUG_KMS("reserving %d bytes of contiguous stolen space for FBC\n",
> + size);
>

I see you've moved this to modeset init. I question whether we even need
it at all.

> compressed_fb = drm_mm_search_free(&dev_priv->mm.stolen, size, 4096, 0);
> if (compressed_fb)
> @@ -111,11 +103,11 @@ static void i915_setup_compression(struct drm_device *dev, int size)
> if (!compressed_fb)
> goto err;
>
> - cfb_base = dev_priv->mm.stolen_base + compressed_fb->start;
> - if (!cfb_base)
> - goto err_fb;
> -
> - if (!(IS_GM45(dev) || HAS_PCH_SPLIT(dev))) {
> + if (HAS_PCH_SPLIT(dev))
> + I915_WRITE(ILK_DPFC_CB_BASE, compressed_fb->start);
> + else if (IS_GM45(dev)) {
> + I915_WRITE(DPFC_CB_BASE, compressed_fb->start);
> + } else {
> compressed_llb = drm_mm_search_free(&dev_priv->mm.stolen,
> 4096, 4096, 0);
> if (compressed_llb)
> @@ -124,56 +116,81 @@ static void i915_setup_compression(struct drm_device *dev, int size)
> if (!compressed_llb)
> goto err_fb;
>
> - ll_base = dev_priv->mm.stolen_base + compressed_llb->start;
> - if (!ll_base)
> - goto err_llb;
> - }
> + dev_priv->compressed_llb = compressed_llb;
>
> - dev_priv->cfb_size = size;
> + I915_WRITE(FBC_CFB_BASE,
> + dev_priv->mm.stolen_base + compressed_fb->start);
> + I915_WRITE(FBC_LL_BASE,
> + dev_priv->mm.stolen_base + compressed_llb->start);
> + }
>
> dev_priv->compressed_fb = compressed_fb;
> - if (HAS_PCH_SPLIT(dev))
> - I915_WRITE(ILK_DPFC_CB_BASE, compressed_fb->start);
> - else if (IS_GM45(dev)) {
> - I915_WRITE(DPFC_CB_BASE, compressed_fb->start);
> - } else {
> - I915_WRITE(FBC_CFB_BASE, cfb_base);
> - I915_WRITE(FBC_LL_BASE, ll_base);
> - dev_priv->compressed_llb = compressed_llb;
> - }
> + dev_priv->cfb_size = size;
>
> - DRM_DEBUG_KMS("FBC base 0x%08lx, ll base 0x%08lx, size %dM\n",
> - (long)cfb_base, (long)ll_base, size >> 20);
> - return;
> + return size;
>
> -err_llb:
> - drm_mm_put_block(compressed_llb);
> err_fb:
> drm_mm_put_block(compressed_fb);
> err:
> dev_priv->no_fbc_reason = FBC_STOLEN_TOO_SMALL;
> - i915_warn_stolen(dev);
> + DRM_INFO("not enough stolen space for compressed buffer (need %d bytes), disabling\n", size);
> + DRM_INFO("hint: you may be able to increase stolen memory size in the BIOS to avoid this\n");
> + return 0;
> +}
> +
> +int i915_gem_stolen_setup_compression(struct drm_device *dev)
> +{
> + struct drm_i915_private *dev_priv = dev->dev_private;
> + struct drm_mm_node *node;
> + unsigned long hole_start, hole_end, size;
> +
> + if (dev_priv->mm.stolen_base == 0)
> + return 0;
> +
> + if (dev_priv->cfb_size)
> + return dev_priv->cfb_size;
> +
> + /* Try to set up FBC with a reasonable compressed buffer size */
> + size = 0;
> + drm_mm_for_each_hole(node, &dev_priv->mm.stolen, hole_start, hole_end) {
> + unsigned long hole_size = hole_end - hole_start;
> + if (hole_size > size)
> + size = hole_size;
> + }
> +
> + /* Try to get a 32M buffer... */
> + if (size > (36*1024*1024))
> + size = 32*1024*1024;
> + else /* fall back to 3/4 of the stolen space */
> + size = size * 3 / 4;
> +
> + return i915_setup_compression(dev, size);
> }
>

It seems a bit silly that you traverse the hole list here only to
traverse it again later with drm_mm_search_free. If you know you want
32MB, how about you try for that with search free, and then if that
fails, go for the drm_mm_for_each_hole?

afaict, this slightly differs from the old code in that it doesn't
respect i915_powersave any longer. I have no issue with that, but if
that's truly not an oversight on my part, something in the commit
message might be nice.

You've also changed from 3/4 to 7/8 for no apparent reason. Not great
for bisecting. At least you updated the comment.

> -static void i915_cleanup_compression(struct drm_device *dev)
> +void i915_gem_stolen_cleanup_compression(struct drm_device *dev)
> {
> struct drm_i915_private *dev_priv = dev->dev_private;
>
> - drm_mm_put_block(dev_priv->compressed_fb);
> + if (dev_priv->cfb_size == 0)
> + return;
> +
> + if (dev_priv->compressed_fb)
> + drm_mm_put_block(dev_priv->compressed_fb);
> +
> if (dev_priv->compressed_llb)
> drm_mm_put_block(dev_priv->compressed_llb);
> +
> + dev_priv->cfb_size = 0;
> }
>
> void i915_gem_cleanup_stolen(struct drm_device *dev)
> {
> - if (I915_HAS_FBC(dev) && i915_powersave)
> - i915_cleanup_compression(dev);
> + i915_gem_stolen_cleanup_compression(dev);
> }
>

I think we lost the meaning of i915_powersave again here, but I could
be mistaken.

> int i915_gem_init_stolen(struct drm_device *dev)
> {
> struct drm_i915_private *dev_priv = dev->dev_private;
> - unsigned long prealloc_size = dev_priv->mm.gtt->stolen_size;
>
> dev_priv->mm.stolen_base = i915_stolen_to_physical(dev);
> if (dev_priv->mm.stolen_base == 0)
> @@ -183,21 +200,7 @@ int i915_gem_init_stolen(struct drm_device *dev)
> dev_priv->mm.gtt->stolen_size, dev_priv->mm.stolen_base);
>
> /* Basic memrange allocator for stolen space */
> - drm_mm_init(&dev_priv->mm.stolen, 0, prealloc_size);
> -
> - /* Try to set up FBC with a reasonable compressed buffer size */
> - if (I915_HAS_FBC(dev) && i915_powersave) {
> - int cfb_size;
> -
> - /* Leave 1M for line length buffer & misc. */
> -
> - /* Try to get a 32M buffer... */
> - if (prealloc_size > (36*1024*1024))
> - cfb_size = 32*1024*1024;
> - else /* fall back to 7/8 of the stolen space */
> - cfb_size = prealloc_size * 7 / 8;
> - i915_setup_compression(dev, cfb_size);
> - }
> + drm_mm_init(&dev_priv->mm.stolen, 0, dev_priv->mm.gtt->stolen_size);
>
> return 0;
> }
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index c2c219b..2ef497d0 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -8351,6 +8351,9 @@ void intel_modeset_init(struct drm_device *dev)
> /* Just disable it once at startup */
> i915_disable_vga(dev);
> intel_setup_outputs(dev);
> +
> + /* Just in case the BIOS is doing something questionable. */
> + intel_disable_fbc(dev);
> }
>
> static void
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 2b3cddf..9ee53cb 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -440,7 +440,7 @@ void intel_update_fbc(struct drm_device *dev)
> dev_priv->no_fbc_reason = FBC_MODULE_PARAM;
> goto out_disable;
> }
> - if (intel_fb->obj->base.size > dev_priv->cfb_size) {
> + if (intel_fb->obj->base.size > i915_gem_stolen_setup_compression(dev)) {
> DRM_DEBUG_KMS("framebuffer too large, disabling "
> "compression\n");
> dev_priv->no_fbc_reason = FBC_STOLEN_TOO_SMALL;
> @@ -526,6 +526,7 @@ out_disable:
> 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)

--
Ben Widawsky, Intel Open Source Technology Center