| Message ID | 53A73110.60405@ti.com |
|---|---|
| State | Accepted |
| Commit | 0244f8f87ec7e327f7a6e45caaa966820eb3fbeb |
| Headers | show |
Hi Rob, On 06/22/2014 10:40 PM, Santosh Shilimkar wrote: > On Friday 20 June 2014 03:46 PM, Rob Herring wrote: >> On Fri, Jun 20, 2014 at 2:02 PM, Santosh Shilimkar >> <santosh.shilimkar@ti.com> wrote: >>> On Friday 20 June 2014 02:56 PM, Arnd Bergmann wrote: >>>> On Friday 20 June 2014 13:17:43 Santosh Shilimkar wrote: >>>>>>> + dma-coherent; >>>>>>> + dma-ranges; >>>>>>> + >>>>>>> + dwc3@2690000 { >>>>>>> + compatible = "synopsys,dwc3"; >>>>>>> + [...] >>>>>>> + }; >>>>>> >>>>>> This example is a bit strange. I don't understand the relationship >>>>>> between keystone-dwc3 and synopsys,dwc3, nor do I want to. I'd prefer >>>>>> to see a simple example here. >>>> >>>> >>>>>> dma-ranges is a property of the parent which you show, but >>>>>> dma-coherent originally was a property of the bus master itself. While >>>>>> we need to support that, are we changing that? We need to be clear on >>>>>> where the property belongs even if the kernel is more lax. >>>>>> >>>>> I don't think we are changing it fundamentally but may be I missing >>>>> your point. The dma-coherent as is now a per-device property. >>>>> USB is one of the bus master supports coherency and hence showed >>>>> up in above example. >>>> >>>> I think it's enough if you just drop the "synopsys,dwc3" node and the >>>> intermediate dma-ranges property from the example, leaving the >>>> dma-coherent property in the "ti,keystone-dwc3" node. >>>> >>> Thanks Arnd. That should avoid the confusion. Just to see if Rob is >>> fine by it, the example will look like below. >> >> Yes. Looks fine. >> > Great. Updated version 2 below. Seems, this patch has not been merged accidentally :( Is it possible for you to take it, or would you like me to re-send it? > > From 7df26004fe11b7d3ef9592161205c69e1fb663be Mon Sep 17 00:00:00 2001 > From: Santosh Shilimkar <santosh.shilimkar@ti.com> > Date: Fri, 20 Jun 2014 11:01:54 -0400 > Subject: [PATCH v2] dt/documentation: add specification of dma bus information > > Recently we introduced the generic device tree infrastructure for couple of DMA > bus parameter, dma-ranges and dma-coherent. Update the documentation so that > its useful for future users. > > The "dma-ranges" property is intended to be used for describing the > configuration of DMA bus RAM addresses and its offset w.r.t CPU addresses. > > The "dma-coherent" property is intended to be used for identifying devices > supported coherent DMA operations. > > Cc: Arnd Bergmann <arnd@arndb.de> > Cc: Grant Likely <grant.likely@linaro.org> > Cc: Rob Herring <robh+dt@kernel.org> > Cc: Pawel Moll <pawel.moll@arm.com> > Cc: Mark Rutland <mark.rutland@arm.com> > Cc: Ian Campbell <ijc+devicetree@hellion.org.uk> > Cc: Kumar Gala <galak@codeaurora.org> > Acked-by: Shawn Guo <shawn.guo@freescale.com> > Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com> > Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com> > --- > Documentation/devicetree/booting-without-of.txt | 53 +++++++++++++++++++++++ > 1 file changed, 53 insertions(+) > > diff --git a/Documentation/devicetree/booting-without-of.txt b/Documentation/devicetree/booting-without-of.txt > index 1f013bd..7768518 100644 > --- a/Documentation/devicetree/booting-without-of.txt > +++ b/Documentation/devicetree/booting-without-of.txt > @@ -51,6 +51,8 @@ Table of Contents > > VIII - Specifying device power management information (sleep property) > > + IX - Specifying dma bus information > + > Appendix A - Sample SOC node for MPC8540 > > > @@ -1332,6 +1334,57 @@ reasonably grouped in this manner, then create a virtual sleep controller > (similar to an interrupt nexus, except that defining a standardized > sleep-map should wait until its necessity is demonstrated). > > +IX - Specifying dma bus information > + > +Some devices may have DMA memory range shifted relatively to the beginning of > +RAM, or even placed outside of kernel RAM. For example, the Keystone 2 SoC > +worked in LPAE mode with 4G memory has: > +- RAM range: [0x8 0000 0000, 0x8 FFFF FFFF] > +- DMA range: [ 0x8000 0000, 0xFFFF FFFF] > +and DMA range is aliased into first 2G of RAM in HW. > + > +In such cases, DMA addresses translation should be performed between CPU phys > +and DMA addresses. The "dma-ranges" property is intended to be used > +for describing the configuration of such system in DT. > + > +In addition, each DMA master device on the DMA bus may or may not support > +coherent DMA operations. The "dma-coherent" property is intended to be used > +for identifying devices supported coherent DMA operations in DT. > + > +* DMA Bus master > +Optional property: > +- dma-ranges: <prop-encoded-array> encoded as arbitrary number of triplets of > + (child-bus-address, parent-bus-address, length). Each triplet specified > + describes a contiguous DMA address range. > + The dma-ranges property is used to describe the direct memory access (DMA) > + structure of a memory-mapped bus whose device tree parent can be accessed > + from DMA operations originating from the bus. It provides a means of > + defining a mapping or translation between the physical address space of > + the bus and the physical address space of the parent of the bus. > + (for more information see ePAPR specification) > + > +* DMA Bus child > +Optional property: > +- dma-ranges: <empty> value. if present - It means that DMA addresses > + translation has to be enabled for this device. > +- dma-coherent: Present if dma operations are coherent > + > +Example: > +soc { > + compatible = "ti,keystone","simple-bus"; > + ranges = <0x0 0x0 0x0 0xc0000000>; > + dma-ranges = <0x80000000 0x8 0x00000000 0x80000000>; > + > + [...] > + > + usb: usb@2680000 { > + compatible = "ti,keystone-dwc3"; > + > + [...] > + dma-coherent; > + }; > +}; > + > Appendix A - Sample SOC node for MPC8540 > ======================================== > > Regards, -grygorii -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri, Sep 19, 2014 at 1:29 PM, Grygorii Strashko <grygorii.strashko@ti.com> wrote: > Hi Rob, > > > On 06/22/2014 10:40 PM, Santosh Shilimkar wrote: >> >> On Friday 20 June 2014 03:46 PM, Rob Herring wrote: >>> >>> On Fri, Jun 20, 2014 at 2:02 PM, Santosh Shilimkar >>> <santosh.shilimkar@ti.com> wrote: >>>> >>>> On Friday 20 June 2014 02:56 PM, Arnd Bergmann wrote: >>>>> >>>>> On Friday 20 June 2014 13:17:43 Santosh Shilimkar wrote: >>>>>>>> >>>>>>>> + dma-coherent; >>>>>>>> + dma-ranges; >>>>>>>> + >>>>>>>> + dwc3@2690000 { >>>>>>>> + compatible = "synopsys,dwc3"; >>>>>>>> + [...] >>>>>>>> + }; >>>>>>> >>>>>>> >>>>>>> This example is a bit strange. I don't understand the relationship >>>>>>> between keystone-dwc3 and synopsys,dwc3, nor do I want to. I'd prefer >>>>>>> to see a simple example here. >>>>> >>>>> >>>>> >>>>>>> dma-ranges is a property of the parent which you show, but >>>>>>> dma-coherent originally was a property of the bus master itself. >>>>>>> While >>>>>>> we need to support that, are we changing that? We need to be clear on >>>>>>> where the property belongs even if the kernel is more lax. >>>>>>> >>>>>> I don't think we are changing it fundamentally but may be I missing >>>>>> your point. The dma-coherent as is now a per-device property. >>>>>> USB is one of the bus master supports coherency and hence showed >>>>>> up in above example. >>>>> >>>>> >>>>> I think it's enough if you just drop the "synopsys,dwc3" node and the >>>>> intermediate dma-ranges property from the example, leaving the >>>>> dma-coherent property in the "ti,keystone-dwc3" node. >>>>> >>>> Thanks Arnd. That should avoid the confusion. Just to see if Rob is >>>> fine by it, the example will look like below. >>> >>> >>> Yes. Looks fine. >>> >> Great. Updated version 2 below. > > > Seems, this patch has not been merged accidentally :( > Is it possible for you to take it, or would you like me to re-send it? Applied. Sorry for the delay. Rob -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/Documentation/devicetree/booting-without-of.txt b/Documentation/devicetree/booting-without-of.txt index 1f013bd..7768518 100644 --- a/Documentation/devicetree/booting-without-of.txt +++ b/Documentation/devicetree/booting-without-of.txt @@ -51,6 +51,8 @@ Table of Contents VIII - Specifying device power management information (sleep property) + IX - Specifying dma bus information + Appendix A - Sample SOC node for MPC8540 @@ -1332,6 +1334,57 @@ reasonably grouped in this manner, then create a virtual sleep controller (similar to an interrupt nexus, except that defining a standardized sleep-map should wait until its necessity is demonstrated). +IX - Specifying dma bus information + +Some devices may have DMA memory range shifted relatively to the beginning of +RAM, or even placed outside of kernel RAM. For example, the Keystone 2 SoC +worked in LPAE mode with 4G memory has: +- RAM range: [0x8 0000 0000, 0x8 FFFF FFFF] +- DMA range: [ 0x8000 0000, 0xFFFF FFFF] +and DMA range is aliased into first 2G of RAM in HW. + +In such cases, DMA addresses translation should be performed between CPU phys +and DMA addresses. The "dma-ranges" property is intended to be used +for describing the configuration of such system in DT. + +In addition, each DMA master device on the DMA bus may or may not support +coherent DMA operations. The "dma-coherent" property is intended to be used +for identifying devices supported coherent DMA operations in DT. + +* DMA Bus master +Optional property: +- dma-ranges: <prop-encoded-array> encoded as arbitrary number of triplets of + (child-bus-address, parent-bus-address, length). Each triplet specified + describes a contiguous DMA address range. + The dma-ranges property is used to describe the direct memory access (DMA) + structure of a memory-mapped bus whose device tree parent can be accessed + from DMA operations originating from the bus. It provides a means of + defining a mapping or translation between the physical address space of + the bus and the physical address space of the parent of the bus. + (for more information see ePAPR specification) + +* DMA Bus child +Optional property: +- dma-ranges: <empty> value. if present - It means that DMA addresses + translation has to be enabled for this device. +- dma-coherent: Present if dma operations are coherent + +Example: +soc { + compatible = "ti,keystone","simple-bus"; + ranges = <0x0 0x0 0x0 0xc0000000>; + dma-ranges = <0x80000000 0x8 0x00000000 0x80000000>; + + [...] + + usb: usb@2680000 { + compatible = "ti,keystone-dwc3"; + + [...] + dma-coherent; + }; +}; + Appendix A - Sample SOC node for MPC8540 ========================================