On Wed, Jul 24, 2024 at 10:12:17AM +0300, Dmitry Baryshkov wrote: > On Wed, 24 Jul 2024 at 06:58, Mayank Rana <quic_mrana@xxxxxxxxxxx> wrote: > > > > > > > > On 7/23/2024 7:13 PM, Dmitry Baryshkov wrote: > > > On Mon, Jul 15, 2024 at 11:13:28AM GMT, Mayank Rana wrote: > > >> Based on previously received feedback, this patch series adds functionalities > > >> with existing PCIe host generic ECAM driver (pci-host-generic.c) to get PCIe > > >> host root complex functionality on Qualcomm SA8775P auto platform. > > >> > > >> Previously sent RFC patchset to have separate Qualcomm PCIe ECAM platform driver: > > >> https://lore.kernel.org/all/d10199df-5fb3-407b-b404-a0a4d067341f@xxxxxxxxxxx/T/ > > >> > > >> 1. Interface to allow requesting firmware to manage system resources and performing > > >> PCIe Link up (devicetree binding in terms of power domain and runtime PM APIs is used in driver) > > >> 2. Performing D3 cold with system suspend and D0 with system resume (usage of GenPD > > >> framework based power domain controls these operations) > > >> 3. SA8775P is using Synopsys Designware PCIe controller which supports MSI controller. > > >> This MSI functionality is used with PCIe host generic driver after splitting existing MSI > > >> functionality from pcie-designware-host.c file into pcie-designware-msi.c file. > > > > > > Please excuse me my ignorance if this is described somewhere. Why are > > > you using DWC-specific MSI handling instead of using GIC ITS? > > Due to usage of GIC v3 on SA8775p with Gunyah hypervisor, we have > > limitation of not supporting GIC ITS > > functionality. We considered other approach as usage of free SPIs (not > > available, limitation in terms of mismatch between number of SPIs > > available with physical GIC vs hypervisor) and extended SPIs (not > > supported with GIC hardware). Hence we just left with DWC-specific MSI > > controller here for MSI functionality. > > ... or extend Gunyah to support GIC ITS. I'd say it is a significant > deficiency if one can not use GIC ITS on Gunyah platforms. > It if were possible, Qcom would've went with that. Unfortunately, it is not. - Mani -- மணிவண்ணன் சதாசிவம்
