[PATCH V2 0/7] Add power domain and MSI functionality with PCIe host generic ECAM driver

[Dmitry Baryshkov]

On Wed, 24 Jul 2024 at 06:58, Mayank Rana <quic_mrana at quicinc.com> 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@quicinc.com/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.

> >> Below architecture is used on Qualcomm SA8775P auto platform to get ECAM compliant PCIe
> >> controller based functionality. Here firmware VM based PCIe driver takes care of resource
> >> management and performing PCIe link related handling (D0 and D3cold). Linux VM based PCIe
> >> host generic driver uses power domain to request firmware VM to perform these operations
> >> using SCMI interface.
> >
> Regards,
> Mayank



-- 
With best wishes
Dmitry