From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Return-Path: From: Arnd Bergmann To: Christoph Hellwig Subject: Re: Support for configurable PCIe endpoint Date: Wed, 03 Aug 2016 18:03:54 +0200 Message-ID: <2460140.yVuTYYqBTX@wuerfel> In-Reply-To: <20160803094747.GA10170@infradead.org> References: <57A18927.9070003@ti.com> <20160803094747.GA10170@infradead.org> MIME-Version: 1.0 List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Gabriele Paoloni , David Daney , "linux-pci@vger.kernel.org" , Thierry Reding , Tanmay Inamdar , Joao Pinto , Pratyush Anand , Kishon Vijay Abraham I , Murali Karicheri , Jason Cooper , Simon Horman , "bhelgaas@google.com" , Mingkai Hu , "linux-omap@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , Thomas Petazzoni , Jingoo Han , Richard Zhu , "linux-kernel@vger.kernel.org" , Stanimir Varbanov , Minghuan Lian , Zhou Wang , jdmason@kudzu.us, Ley Foon Tan , Roy Zang , Lucas Stach Content-Type: text/plain; charset="us-ascii" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+bjorn=helgaas.com@lists.infradead.org List-ID: 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 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel