> -----Original Message----- > From: [email protected] [mailto:linux-kernel- > [email protected]] On Behalf Of Bharat Bhushan > Sent: Thursday, August 31, 2017 4:53 PM > To: Marc Zyngier <[email protected]>; [email protected]; Mark > Rutland <[email protected]>; [email protected]; > [email protected]; Gang Liu <[email protected]>; > [email protected]; [email protected]; linux- > [email protected]; [email protected] > Subject: RE: [PATCH] RM64: dts: ls208xa: Add iommu-map property for pci > > > > > -----Original Message----- > > From: Marc Zyngier [mailto:[email protected]] > > Sent: Thursday, August 31, 2017 4:20 PM > > To: Bharat Bhushan <[email protected]>; [email protected]; > Mark > > Rutland <[email protected]>; [email protected]; > [email protected]; > > Gang Liu <[email protected]>; [email protected]; > > [email protected]; linux- [email protected]; > > [email protected] > > Subject: Re: [PATCH] RM64: dts: ls208xa: Add iommu-map property for > > pci > > > > [Fixing Mark's address...] > > > > On 31/08/17 11:41, Bharat Bhushan wrote: > > > > > >> -----Original Message----- > > >> From: Marc Zyngier [mailto:[email protected]] > > >> Sent: Thursday, August 31, 2017 3:02 PM > > >> To: Bharat Bhushan <[email protected]>; [email protected]; > > >> [email protected]; [email protected]; [email protected]; Gang > > Liu > > >> <[email protected]>; [email protected]; linux-arm- > > >> [email protected]; [email protected]; > > >> [email protected] > > >> Subject: Re: [PATCH] RM64: dts: ls208xa: Add iommu-map property for > > >> pci > > >> > > >> On 31/08/17 10:23, Bharat Bhushan wrote: > > >>> This patch adds iommu-map property for PCIe, which enables SMMU > > >>> for these devices on LS208xA devices. > > >>> > > >>> Signed-off-by: Bharat Bhushan <[email protected]> > > >>> --- > > >>> arch/arm64/boot/dts/freescale/fsl-ls208xa.dtsi | 4 ++++ > > >>> 1 file changed, 4 insertions(+) > > >>> > > >>> diff --git a/arch/arm64/boot/dts/freescale/fsl-ls208xa.dtsi > > >>> b/arch/arm64/boot/dts/freescale/fsl-ls208xa.dtsi > > >>> index 94cdd30..67cf605 100644 > > >>> --- a/arch/arm64/boot/dts/freescale/fsl-ls208xa.dtsi > > >>> +++ b/arch/arm64/boot/dts/freescale/fsl-ls208xa.dtsi > > >>> @@ -606,6 +606,7 @@ > > >>> num-lanes = <4>; > > >>> bus-range = <0x0 0xff>; > > >>> msi-parent = <&its>; > > >>> + iommu-map = <0 &smmu 0 1>; /* This is > > >>> fixed-up by > > >> u-boot */ > > >> > > >> What does this do when your version of u-boot doesn't fill this in for > you? > > > > > > Good question, frankly I have not thought of this case before. > > > But if we pass length = 0 in above property then no fixup happen > > > with happen with older u-boot. In this case of_iommu_configure() > > > will return NULL iommu-ops and it switch to swio-tlb. Will that work? > > I really don't like this. You rely on having invalid data in the DT, > > and that seems just wrong. > > > > Why can't u-boot just generate that property, and we leave the DT alone? > > We do not have smmu phandle allowing uboot to generate this. > > > Or even better, you provide the right information for the few boards > > that are based on this SoC, not relying on u-boot for anything that is > > in the kernel tree? > > On our platforms we have a h/w table which converts RID->Device-Id. I will > check what will happen if that table is not initialized, can RID be equal to > device-id is that case. > If that will be allowed than we can give right information that will work with > u-boot not updating this property.
U-boot uses a stream-id allocator and programs the h/w mapping table (rid to sid mapping table). Also it updates iommu-map property accordingly. But If u-boot does not update iommu-map than we cannot have a valid full proof solution as stream-id allocation can change in u-boot. So the other option of u-boot generating this entry seems correct solution. This requires u-boot to know iommu-phandle, something similar to "msi-parent" used for "msi-map" Device-tree binding need change to add iommu-phandle/iommu-parent for this. Thanks -Bharat > > Will revert after confirming this. > > Thanks > -Bharat > > > > Thanks, > > > > M. > > -- > > Jazz is not dead. It just smells funny...
