| Message ID | 1389245428-10880-1-git-send-email-akash.goel@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Jan 09, 2014 at 11:00:28AM +0530, akash.goel@intel.com wrote: > From: Akash Goel <akash.goel@intel.com> > > There is a conflict seen when requesting the kernel to reserve > the physical space used for the stolen area. This is because > as somehow the start/base location of the Parent region > of Stolen area which is PCI Bus 0000:00 is not coinciding with > the start of Stolen area and is conflicting with it. For ex. > from the device memory map info provided by '/proc/iomem', > we have seen that somehow a region of PCI Bus 0000:00 is being > shown to start from 0x7b000001, > i.e. (7b000001-ffffffff : PCI Bus 0000:00) & not from > 0x7b000000. And the stolen base is coming as 0x7b000000, > thus there is a conflict & stolen area remains unused by driver. > So to circumvent this issue we adjust the base of stolen area by > 1 byte when registering it with the kernel. > Otherwise if we don't resolve this conflict or don't remove the > conflict error check from the driver, the stolen area will remain > disabled. > > Signed-off-by: Akash Goel <akash.goel@intel.com> > --- > drivers/gpu/drm/i915/i915_gem_stolen.c | 27 ++++++++++++++++++++++++--- > 1 file changed, 24 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c b/drivers/gpu/drm/i915/i915_gem_stolen.c > index 1a24e84..29b3693 100644 > --- a/drivers/gpu/drm/i915/i915_gem_stolen.c > +++ b/drivers/gpu/drm/i915/i915_gem_stolen.c > @@ -82,9 +82,30 @@ static unsigned long i915_stolen_to_physical(struct drm_device *dev) > r = devm_request_mem_region(dev->dev, base, dev_priv->gtt.stolen_size, > "Graphics Stolen Memory"); > if (r == NULL) { > - DRM_ERROR("conflict detected with stolen region: [0x%08x - 0x%08x]\n", > - base, base + (uint32_t)dev_priv->gtt.stolen_size); > - base = 0; > + /* One more attempt but this time requesting region from > + * base + 1, as we have seen that this resolves the region > + * conflict with the PCI Bus. > + * This is because as somehow the start/base location of > + * the Parent region of Stolen area which is PCI Bus 0000:00 > + * is not coinciding with the start of Stolen area and is > + * conflicting with it. For ex. from the device memory map > + * info provided by '/proc/iomem', we have seen that somehow > + * a region of PCI Bus 0000:00 is being shown to start from > + * 0x7b000001, i.e. (7b000001-ffffffff : PCI Bus 0000:00). > + * And the stolen base is coming as 0x7b000000, thus there is a > + * conflict and stolen memory remains unused by the driver. > + * So to circumvent this issue we adjust the base of stolen > + * area by 1 when registering it with the kernel. > + */ I think this comment can be shortened a bit: /* * BIOS w/a: Some BIOS wrap stolen in the root PCI bus, * but have an off-by-one error. Hence retry the * reservation starting from 1 instead of 0. */ Curious readers can then bring up the full details with git blame. Also note that we now prefer the multi-line comment delimiters /* and */ on separate lines. Cheers, Daniel > + r = devm_request_mem_region(dev->dev, base + 1, > + dev_priv->gtt.stolen_size - 1, > + "Graphics Stolen Memory"); > + if (r == NULL) { > + DRM_ERROR("conflict detected with stolen region:"\ > + "[0x%08x - 0x%08x]\n", > + base, base + (uint32_t)dev_priv->gtt.stolen_size); > + base = 0; > + } > } > > return base; > -- > 1.8.5.2 > > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c b/drivers/gpu/drm/i915/i915_gem_stolen.c index 1a24e84..29b3693 100644 --- a/drivers/gpu/drm/i915/i915_gem_stolen.c +++ b/drivers/gpu/drm/i915/i915_gem_stolen.c @@ -82,9 +82,30 @@ static unsigned long i915_stolen_to_physical(struct drm_device *dev) r = devm_request_mem_region(dev->dev, base, dev_priv->gtt.stolen_size, "Graphics Stolen Memory"); if (r == NULL) { - DRM_ERROR("conflict detected with stolen region: [0x%08x - 0x%08x]\n", - base, base + (uint32_t)dev_priv->gtt.stolen_size); - base = 0; + /* One more attempt but this time requesting region from + * base + 1, as we have seen that this resolves the region + * conflict with the PCI Bus. + * This is because as somehow the start/base location of + * the Parent region of Stolen area which is PCI Bus 0000:00 + * is not coinciding with the start of Stolen area and is + * conflicting with it. For ex. from the device memory map + * info provided by '/proc/iomem', we have seen that somehow + * a region of PCI Bus 0000:00 is being shown to start from + * 0x7b000001, i.e. (7b000001-ffffffff : PCI Bus 0000:00). + * And the stolen base is coming as 0x7b000000, thus there is a + * conflict and stolen memory remains unused by the driver. + * So to circumvent this issue we adjust the base of stolen + * area by 1 when registering it with the kernel. + */ + r = devm_request_mem_region(dev->dev, base + 1, + dev_priv->gtt.stolen_size - 1, + "Graphics Stolen Memory"); + if (r == NULL) { + DRM_ERROR("conflict detected with stolen region:"\ + "[0x%08x - 0x%08x]\n", + base, base + (uint32_t)dev_priv->gtt.stolen_size); + base = 0; + } } return base;