On Mon, Jun 13, 2016 at 05:01:53PM +0100, Jose Abreu wrote: > Hi Vinod, > > Thanks for your answer! > > > On 13-06-2016 06:30, Vinod Koul wrote: > > On Thu, Jun 09, 2016 at 04:48:38PM +0100, Jose Abreu wrote: > >> Hi all, > >> > >> Currently I am using Xilinx VDMA in a FPGA that is connected to a > >> x64 platform using PCIe. As x64 does not use device tree I needed > >> to add support for platform data in the Xilinx VDMA driver. Do > >> you think that this change can be a submittable patch to > >> mainline? The patch is fairly simple but it was made against the > >> previous version of the driver that only supports AXI VDMA. I've > >> seen that support for AXI DMA and AXI CDMA was recently added so > >> the patch needs to be rebased. > >> > >> My main doubt about this being submittable is because I really > >> don't know how the use of platform data is seen by you guys so I > >> would really appreciate some feedback about this. > > Platform data should be okay, but who will initialize that? > > In my setup I am using a PCI driver that populates the platform > data structure and registers the VDMA driver. > > > > > Shouldn't your device be a ACPI device? > > Well, I am not very familiar with ACPI but for what I've read it > is not applicable in this case because the VDMA device is not > inherently discoverable by PCI. It is connected to the PC using > PCIe which in turn connects to the FPGA. The host knows it has a > PCI device but the device itself is composed by many sub-blocks > (vdma, video timing controller, HDMI Phy, ...). Besides, the ACPI > tables are hardcoded into the BIOS, right? If yes, then I think > it is not an ideal solution. ACPI is quite like DT for x86! ACPI has device tables which describe the devices which are not discoverable. (not everything in x86 is discoverable) Yes these are hard coded in BIOS, but if you are connecting FPGA and providing additional functionality then BIOS update would be required to describe all these For testing you can patch DSDT and add additional entries and data. The problem with platform approach is platform data, how will that be managed and how will that live in kernel for various systems we will use this in! -- ~Vinod -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
