On Wednesday, August 3, 2016 2:47:47 AM CEST Christoph Hellwig wrote: > On Wed, Aug 03, 2016 at 11:33:19AM +0530, Kishon Vijay Abraham I wrote: > > Hi, > > > > The PCIe controller present in TI's DRA7 SoC is capable of operating either in > > Root Complex mode or Endpoint mode. (It uses Synopsys Designware Core).I'd > > assume most of the PCIe controllers on other platforms that use Designware core > > should also be capable to operate in endpoint mode. But linux kernel right now > > supports only RC mode. > > > > PCIe endpoint support discussion came up briefly before [1] but it was felt the > > practical use case will find firmware more suitable and endpoint support in > > kernel can be used only for validation or demo. > > I disagree. It's highly useful for rapid prototyping of hardware > interfaces, and I've been looking into PCIe EP drivers for exactly > that reason recently. Going a little offtopic: any good DRA7 eval > boards you'd recommend to try for this purpose? > > We already have a EP driver in the tree: > > drivers/misc/spear13xx_pcie_gadget.c > > but as far as I can tell it doesn't really work at the moment. > This is indeed for the designware pcie hardware, but it never worked in a mainline kernel, and I marked it 'depends on BROKEN' after it had not correctly compiled for a long time. It's also lacking because it neither abstracts the hardware nor the protocol, and I think we want both. drivers/ntb seems like a reasonable start, while an alternative approach that we have discussed in the past would be based on top of virtio, so we could use the existing front-end drivers (net, block, v9fs, console, ...). Arnd -- 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
