i915 mapping large (3MB) scatter list, hitting limits on certain IOMMUs that can only map contingous regions up to 2MB.
Jerome Glisse
j.glisse at gmail.com
Tue Jun 25 08:03:01 PDT 2013
On Fri, Jun 21, 2013 at 3:28 PM, Konrad Rzeszutek Wilk
<konrad.wilk at oracle.com> wrote:
> Hey,
>
> I am using an ThinkPad X230 with an Intel HD 4000. With a stock Fedora 18
> (3.9.6) I can get it to boot and work just fine with Xen. If I use v3.10-rc6
> I found that i915 would halt with a
>
> [drm:intel_pipe_set_base] *ERROR* pin & fence failed
> [drm:intel_crtc_set_config] *ERROR* failed to set mode on [CRTC:3], err = -28
>
> after a bit of debugging (see patch below) I traced it down
> to the fact that the scatter list that is provided at the end has
> a huge (3MB) page. I am wondering if anybody knows what patch might
> have introduced it to grab such a large memory segment?
>
> The other thing I am wondering is if there are some fallbacks when the
> underlaying IOMMU can't deal with a request for contingous regions
> that are more than 2MB?
There is no fallback afaik, but most gpu have their own mmu so they
don't really need contiguous iommu mapping, all they need is at the
very least being able to access all page of large object. Probably
something we should take a look at.
Cheers,
Jerome
> Thanks.
>
> From a681a4adb4738c32cb1acdf6f5161bf877816b01 Mon Sep 17 00:00:00 2001
> From: Konrad Rzeszutek Wilk <konrad.wilk at oracle.com>
> Date: Fri, 21 Jun 2013 11:17:55 -0400
> Subject: [PATCH] dbug: print scatterlist.
>
> ------------[ cut here ]------------
> WARNING: at drivers/gpu/drm/i915/i915_gem_gtt.c:418 i915_gem_gtt_prepare_object+0x180/0x200()
> 10 but got 0
> Modules linked in:
> crc32_pclmul sdhci_pci crc32c_intel sdhci mmc_core ghash_clmulni_intel
> CPU: 0 PID: 216 Comm: plymouthd Not tainted 3.10.0-rc6+ #16
> Hardware name: LENOVO 2325DV4/2325DV4, BIOS G2ET86WW (2.06 ) 11/13/2012
> 0000000000000009 ffff8801fa42d958 ffffffff816e6d89 ffff8801fa42d998
> ffffffff8105d2b0 ffff8801fa42d988 0000000000000000 ffff8801fb0f4d80
> ffffffff81c172e0 ffff8801fa76f000 000000000000000a ffff8801fa42d9f8
> Call Trace:
> [<ffffffff816e6d89>] dump_stack+0x19/0x1b
> [<ffffffff8105d2b0>] warn_slowpath_common+0x70/0xa0
> [<ffffffff8105d396>] warn_slowpath_fmt+0x46/0x50
> [<ffffffff8142a740>] i915_gem_gtt_prepare_object+0x180/0x200
> [<ffffffff81423581>] i915_gem_object_pin+0x321/0x670
> [<ffffffff81423951>] i915_gem_object_pin_to_display_plane+0x81/0x190
> [<ffffffff814381b5>] intel_pin_and_fence_fb_obj+0x85/0x1a0
> [<ffffffff8143999c>] intel_pipe_set_base+0x7c/0x220
> [<ffffffff814409be>] intel_crtc_set_config+0x89e/0x990
> [<ffffffff813ffdae>] drm_mode_set_config_internal+0x2e/0x60
> [<ffffffff814023ab>] drm_mode_setcrtc+0xfb/0x620
> [<ffffffff811850f9>] ? kmem_cache_alloc_trace+0x39/0x1f0
> [<ffffffff813f9767>] ? drm_vm_open_locked+0x57/0x90
> [<ffffffff813f2e39>] drm_ioctl+0x549/0x680
> [<ffffffff814022b0>] ? drm_mode_setplane+0x3b0/0x3b0
> [<ffffffff811aef77>] do_vfs_ioctl+0x97/0x580
> [<ffffffff81295dca>] ? inode_has_perm.isra.32.constprop.62+0x2a/0x30
> [<ffffffff81297397>] ? file_has_perm+0x97/0xb0
> [<ffffffff811af4f1>] SyS_ioctl+0x91/0xb0
> [<ffffffff816f63e7>] tracesys+0xdd/0xe2
> ---[ end trace 7b6adc5450d9a9e1 ]---
> i915 0000:00:02.0: i915_gem_gtt_prepare_object: Mapping 10 pages, mapped: 0
> [0] virT:ffff8801fd37c000 dma: 1fd37c000, size:4096
> [1] virT:ffff8801fd37b000 dma: 1fd37b000, size:4096
> [2] virT:ffff8801fd37a000 dma: 1fd37a000, size:4096
> [3] virT:ffff8801fd378000 dma: 1fd378000, size:4096
> [4] virT:ffff8801fd131000 dma: 1fd131000, size:4096
> [5] virT:ffff880200c36000 dma: 200c36000, size:4096
> [6] virT:ffff8801fd1a4000 dma: 1fd1a4000, size:69632
> [7] virT:ffff8801fd3bb000 dma: 1fd3bb000, size:4096
> [8] virT:ffff8801fd3c0000 dma: 1fd3c0000, size:262144
> [9] virT:ffff8801f9400000 dma: 1f9400000, size:3866624
> [drm] 3011: ret:-28
> [drm] 3540: ret:-28
> [drm] 3364: ret:-28
> [drm:intel_pin_and_fence_fb_obj] *ERROR* i915_gem_object_pin_to_display_plane failed: -28
> [drm:intel_pipe_set_base] *ERROR* pin & fence failed
> [drm:intel_crtc_set_config] *ERROR* failed to set mode on [CRTC:3], err = -28
>
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk at oracle.com>
> ---
> drivers/gpu/drm/i915/i915_drv.c | 6 ++++++
> drivers/gpu/drm/i915/i915_gem_gtt.c | 28 +++++++++++++++++++++++++---
> 2 files changed, 31 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index 8411942..141c6fb 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -133,6 +133,12 @@ module_param_named(coherent, use_coherent, int, 0600);
> MODULE_PARM_DESC(use_coherent,
> "Use coherent DMA API calls (default: false)");
>
> +int i915_sgl __read_mostly = 0;
> +module_param_named(sgl, i915_sgl, int, 0600);
> +MODULE_PARM_DESC(sgl,
> + "Print scatterlist SG's when DMA mapping them (default: false)");
> +
> +
> static struct drm_driver driver;
> extern int intel_agp_enabled;
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index acb3b3f..292179c 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -28,6 +28,7 @@
> #include "i915_trace.h"
> #include "intel_drv.h"
>
> +extern int use_coherent;
> typedef uint32_t gen6_gtt_pte_t;
>
> /* PPGTT stuff */
> @@ -403,15 +404,36 @@ void i915_gem_restore_gtt_mappings(struct drm_device *dev)
>
> i915_gem_chipset_flush(dev);
> }
> -
> +extern int i915_sgl;
> int i915_gem_gtt_prepare_object(struct drm_i915_gem_object *obj)
> {
> + int elem;
> if (obj->has_dma_mapping)
> return 0;
>
> - if (!dma_map_sg(&obj->base.dev->pdev->dev,
> + elem = dma_map_sg(&obj->base.dev->pdev->dev,
> obj->pages->sgl, obj->pages->nents,
> - PCI_DMA_BIDIRECTIONAL))
> + PCI_DMA_BIDIRECTIONAL);
> +
> + WARN(elem == 0, "%d but got %d", obj->pages->nents, elem);
> +
> + if (i915_sgl && obj->pages && obj->pages->sgl) {
> + int i;
> + struct scatterlist *s;
> +
> + if (obj->base.dev) {
> + dev_info(&obj->base.dev->pdev->dev, "%s: Mapping %d pages, mapped: %d\n",
> + __func__,obj->pages->nents, elem);
> + } else
> + printk(KERN_INFO "%s: no dev, %d pages, mapped: %d\n",__func__,
> + obj->pages->nents, elem);
> +
> + for_each_sg(obj->pages->sgl, s, obj->pages->nents, i) {
> + printk(KERN_INFO "[%d] virT:%lx dma: %lx, size:%d\n", i,
> + (unsigned long)sg_virt(s), (unsigned long)sg_phys(s), s->length);
> + }
> + }
> + if (!elem)
> return -ENOSPC;
>
> return 0;
> --
> 1.8.1.4
>
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