On Tuesday 09 September 2014 18:46:59 Lian Minghuan-B31939 wrote: > On 2014年09月09日 09:56, Arnd Bergmann wrote: > > On Tuesday 09 September 2014 17:25:57 Lian Minghuan-B31939 wrote: > >> [Minghuan] I discussed with my colleague. They worry about performance > >> degradation if using regmap API, > >> because there are some fast device use scfg. We tend to use a simple way > >> to map andread/write scfg directly. > > > > I see. In this case, I would probably create a separate msi controller > > driver that owns the "fsl,ls1021a-scfg" device, and is referenced > > through the "msi-parent" property in the pcie controller. > > > > You can use of_pci_find_msi_chip_by_node() to get the msi_chip > > instance and then connect that to your pci host. This will also > > take care of the case where you may want to use the main GICv3 > > > on a future SoC. > [Minghuan] There is something wrong with LS1021A MSI hardware that it > only supports one interrupt not 32 interrupts. Now, I do not want to > create a separate msi controller driver just for incorrect hardware. > I may provide complete MSI driver for the new hardware when it is ready. Would you just leave out MSI support for the LS1021A PCIe variant? I guess that's fine because all device drivers should also support legacy interrupts and there is no performance gain in MSI in this case. 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
