On Thu, Mar 17, 2011 at 11:08:19AM -0600, Grant Likely wrote: > On Thu, Mar 17, 2011 at 12:31:15PM +0800, Shawn Guo wrote: > > On Wed, Mar 16, 2011 at 05:05:00PM -0600, Grant Likely wrote: > > > > > [...] > > > I'd like to have feedback on the new code to make sure that the model > > > is sane. There are some fiddly code it there which is used to match > > > platform_device registrations to nodes in the device tree. I *think* > > > it makes sense, but I'd like to hear other opinions. > > > > > Binding platform_device with of_node via resources matching seems a > > little fiddly, but your implementation looks solid to me. I made a > > quick scan on all the platform_device registration under > > arch/arm/plat-mxc/devices, nothing would be broken, only except > > platform-gpio_keys which is not an on-chip device. > > Right; and doing it this way doesn't make sense for anything that is > board/system specific because if the board is using the DT, then it is > simpler and more reliable to avoid the matching heuristic entirely. > > > Looking at the code, I'm wondering how the binding of resource type > > IORESOURCE_DMA looks like. I'm seeing some platform_device is using > > this flag to tell dma channel fixed for the device. I'm not sure if > > it can be fit in property 'dma-ranges'. And I only see IORESOURCE_MEM > > and IORESOURCE_IRQ being used in the matching model. > > The matching is simply a heuristic that makes a best guess about how > how device nodes line up with platform_device registrations. Right > now the heuristic is to look at the register ranges and irqs described > in the node and make sure that each of them are listed in the > platform_device. If the platform_device has additional resources, > then it simply ignores them. That seems to be sufficient for accurate > matching, but I won't know for sure until people start using it. > > If there are situations where the heuristic does not work, then I'd > like to know what they are so that the algorithm can be fixed, or in > the absolute worst case implement workaround logic. > > One option I'm considering which would improve the accuracy of the > heuristic is to add a 'char *of_compatible' field to struct > platform_device. Then platform_devices could optionally be tagged > with the compatible value that must be present in order to be matched > with a node. > > I definitely want feedback on the matching heuristic! > Tested on babbage with serial, fec and esdhc drivers, and I did see it solves problems of clkdev dev_id matching and pdev->id use. And it even helped to discover one problem with .end definition of fec resource IORESOURCE_MEM. I will send mainline a patch for that soon.
-- Regards, Shawn _______________________________________________ linaro-dev mailing list linaro-dev@lists.linaro.org http://lists.linaro.org/mailman/listinfo/linaro-dev
