This set implements two changes to the support we have in EmbeddedPkg for non-coherent DMA, which together should allow the Raspberry Pi4 to use both the platform and PCI based DMA devices.
Patch #1 implements support for limiting DMA to a certain memory region. This is necessary given that the RPi4 ships with more than 1 GB of memory in some configurations, but uses DMA translation for the platform devices in a way that puts that memory out of reach for 32-bit DMA (i.e., the DMA translation is +3 GB). By setting the device DMA limit to MAX_UINT32, the library will infer a host address limit of 1 GB, and use bounce buffering if any buffers are mapped outside that region. Patch #2 implements a trivial wrapper around DmaLib that exposes the EDK2 IoMmu protocol. This is used by the generic PCI infrastructure instead of the builtin DMA routines when the protocol exists, so it is a natural place to implement the non-cache coherent DMA handling we need for the RPi4. Tested on Raspberry Pi 4. Changes since v1: - fix a few major issues in #1 - add Leif's ack to #2 Cc: awarken...@vmware.com Cc: jeremy.lin...@arm.com Cc: p...@akeo.ie Cc: samer.el-haj-mahm...@arm.com Ard Biesheuvel (2): EmbeddedPkg/NonCoherentDmaLib: implement support for DMA range limits EmbeddedPkg: implement EDK2 IoMmu protocol wrapping DmaLib .../NonCoherentIoMmuDxe/NonCoherentIoMmuDxe.c | 257 ++++++++++++++++++ .../NonCoherentIoMmuDxe.inf | 43 +++ EmbeddedPkg/EmbeddedPkg.dec | 6 + EmbeddedPkg/EmbeddedPkg.dsc | 5 + .../NonCoherentDmaLib/NonCoherentDmaLib.c | 165 ++++++++++- .../NonCoherentDmaLib/NonCoherentDmaLib.inf | 1 + 6 files changed, 465 insertions(+), 12 deletions(-) create mode 100644 EmbeddedPkg/Drivers/NonCoherentIoMmuDxe/NonCoherentIoMmuDxe.c create mode 100644 EmbeddedPkg/Drivers/NonCoherentIoMmuDxe/NonCoherentIoMmuDxe.inf -- 2.17.1 -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#51252): https://edk2.groups.io/g/devel/message/51252 Mute This Topic: https://groups.io/mt/61950461/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
