Hi Arnd, On Tuesday 13 May 2014 06:17 PM, Arnd Bergmann wrote: > On Tuesday 13 May 2014 18:01:59 Kishon Vijay Abraham I wrote: >> On Thursday 08 May 2014 02:48 PM, Arnd Bergmann wrote: >>> On Thursday 08 May 2014 18:05:11 Jingoo Han wrote: >>>> On Tuesday, May 06, 2014 10:59 PM, Arnd Bergmann wrote: >>>>> On Tuesday 06 May 2014 19:03:52 Kishon Vijay Abraham I wrote: >>>>>> In DRA7, the cpu sees 32bit address, but the pcie controller can see only 28bit >>>>>> address. So whenever the cpu issues a read/write request, the 4 most >>>>>> significant bits are used by L3 to determine the target controller. >>>>>> For example, the cpu reserves 0x2000_0000 - 0x2FFF_FFFF for PCIe controller but >>>>>> the PCIe controller will see only (0x000_0000 - 0xFFF_FFF). So for programming >>>>>> the outbound translation window the *base* should be programmed as 0x000_0000. >>>>>> Whenever we try to write to say 0x2000_0000, it will be translated to whatever >>>>>> we have programmed in the translation window with base as 0x000_0000. >>>>>> >>>>>> Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> >>>>>> Cc: Marek Vasut <marex@xxxxxxx> >>>>>> Signed-off-by: Kishon Vijay Abraham I <kishon@xxxxxx> >>>>>> Acked-by: Jingoo Han <jg1.han@xxxxxxxxxxx> >>>>>> Acked-by: Mohit Kumar <mohit.kumar@xxxxxx> >>>>> >>>>> Sorry, but NAK. >>>>> >>>>> We have a standard 'dma-ranges' property to handle this, so use it. >>>>> >>>>> See the x-gene PCIe driver patches for an example. Please also talk >>>>> to Santosh about it, as he is implementing generic support for >>>>> parsing dma-ranges in platform devices at the moment. >>>> >>>> Hi Arnd, >>>> >>>> Do you mean the following patch? >>>> http://www.spinics.net/lists/kernel/msg1737725.html >>>> >>> >>> That is the patch Santosh did for platform devices, which is related but not >>> what I meant here. For the PCI inbound window setup, please have a look >>> at https://lkml.org/lkml/2014/3/19/607 >> >> Do you think it can be used for *outbound* window setup too? The problem is the >> *ranges* property defines both the pci address and cpu address which should >> have been enough to program the ob translation window, but the hw is designed >> so that the controller sees only the 28 bits. (The most significant 4 bits is >> for the l3 to address the controller). > > I'm not following what the problem is. You should always be able to describe > in the inbound window (that is from the CPU perspective) using dma-ranges > and the outbound window using ranges. > > If you have a case where the outbound translation is a 256MB (i.e. 28bit) > section of the CPU address space, that could be represented as > > ranges = <0x82000000 0 0 0xb0000000 0 0x10000000>; > > or > > ranges = <0x82000000 0 0xb0000000 0xb0000000 0 0x10000000>; > > depending on whether you want the BARs to be programmed using a low > address 0x0-0x0fffffff or an address matching the window > 0xb0000000-0xbfffffff. The problem is, for configuring the window starting at 0xb0000000, the ATU should be programmed 0x0000000 (the cpu address for it will be 0xb0000000 though). Thanks Kishon -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
