Hi Rob, On Tue, Jul 02, 2019 at 01:26:18PM -0700, Rob Clark wrote: > 1) In some cases the bootloader takes the iommu out of bypass and > enables the display. This is in particular a problem on the aarch64 > laptops that exist these days, and modern snapdragon android devices. > (Older devices also enabled the display in bootloader but did not > take the iommu out of bypass.) Attaching a DMA or IDENTITY domain > while scanout is active, before the driver has a chance to intervene, > makes things go *boom* Just to make sure I get this right: The bootloader inializes the SMMU and creates non-identity mappings for the GPU? And when the SMMU driver in Linux takes over this breaks display output. > + /* > + * If driver is going to manage iommu directly, then avoid > + * attaching any non driver managed domain. There could > + * be already active dma underway (ie. scanout in case of > + * bootloader enabled display), and interfering with that > + * will make things go *boom* > + */ > + if ((domain->type != IOMMU_DOMAIN_UNMANAGED) && > + dev->driver && dev->driver->driver_manages_iommu) > + return 0; > + When the default domain is attached, there is usually no driver attached yet. I think this needs to be communicated by the firmware to Linux and the code should check against that. > - bool suppress_bind_attrs; /* disables bind/unbind via sysfs */ > + bool suppress_bind_attrs:1; /* disables bind/unbind via sysfs */ > + bool driver_manages_iommu:1; /* driver manages IOMMU explicitly */ How does this field get set? Joerg _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
