On Thu, Aug 31, 2017 at 11:49:37AM +0100, Marc Zyngier wrote: > [Fixing Mark's address...]
Thanks! > 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. Indeed. Either the property should be valid (and correctly representing the HW), or it shouldn't be present. Relying on kernel implementation details is *not* OK. Thanks, Mark.
