On Mon, Jul 18, 2022 at 06:46:32AM +0000, Manne, Nava kishore wrote: > Hi Yilun, > > Please find my response inline. > > > -----Original Message----- > > From: Xu Yilun <yilun.xu@xxxxxxxxx> > > Sent: Friday, June 24, 2022 9:58 PM > > To: Nava kishore Manne <nava.manne@xxxxxxxxxx> > > Cc: mdf@xxxxxxxxxx; hao.wu@xxxxxxxxx; trix@xxxxxxxxxx; > > robh+dt@xxxxxxxxxx; krzysztof.kozlowski+dt@xxxxxxxxxx; > > michal.simek@xxxxxxxxxx; linux-fpga@xxxxxxxxxxxxxxx; > > devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-arm- > > kernel@xxxxxxxxxxxxxxxxxxx; git@xxxxxxxxxx; Rob Herring <robh@xxxxxxxxxx> > > Subject: Re: [PATCH v2 2/3] fpga: region: Add fpga-region 'power-domains' > > property > > > > CAUTION: This message has originated from an External Source. Please use > > proper judgment and caution when opening attachments, clicking links, or > > responding to this email. > > > > > > On Mon, May 23, 2022 at 07:15:16PM +0530, Nava kishore Manne wrote: > > > Add fpga-region 'power-domains' property to allow to handle the > > > FPGA/PL power domains. > > > > > > Signed-off-by: Nava kishore Manne <nava.manne@xxxxxxxxxx> > > > Acked-by: Rob Herring <robh@xxxxxxxxxx> > > > --- > > > Changes for v2: > > > - Updated power-domains description. > > > > > > .../devicetree/bindings/fpga/fpga-region.txt | 14 ++++++++++++++ > > > 1 file changed, 14 insertions(+) > > > > > > diff --git a/Documentation/devicetree/bindings/fpga/fpga-region.txt > > > b/Documentation/devicetree/bindings/fpga/fpga-region.txt > > > index 7d3515264838..f299c3749505 100644 > > > --- a/Documentation/devicetree/bindings/fpga/fpga-region.txt > > > +++ b/Documentation/devicetree/bindings/fpga/fpga-region.txt > > > @@ -196,6 +196,20 @@ Optional properties: > > > - config-complete-timeout-us : The maximum time in microseconds time > > for the > > > FPGA to go to operating mode after the region has been programmed. > > > - child nodes : devices in the FPGA after programming. > > > +- power-domains : A phandle and power domain specifier pair to the > > power domain > > > + which is responsible for turning on/off the power to the FPGA/PL > > region. > > > > Could you help explain what is PL? > > > > > +Example: > > > + fpga_full: fpga-full { > > > + compatible = "fpga-region"; > > > + fpga-mgr = <&zynqmp_pcap>; > > > + #address-cells = <2>; > > > + #size-cells = <2>; > > > + ranges; > > > + power-domains = <&zynqmp_firmware PL_PD>; > > > + }; > > > + > > > + The PL_PD power domain will be turned on before loading the > > > +bitstream and turned off while removing/unloading the bitstream using > > overlays. > > > > I think the single power-domain may not cover some use cases that of-fpga- > > region driver supports. > > I am not sure which use case you are talking about. Can you please point me the exact use case here? > > > It is possible there are already devices in fpga-region > > for static OF tree, or an overlay with no 'firmware-name' but 'external-fpga- > > config'. In these cases power domains may still be needed, is it? > > > > It's an optional property user can decide whether he needs this support or not for 'external-fpga-config > Use case. If an external-fpga-config FPGA region needs to enable a power domain before sub devices population, how could it config the DT? I assume in this patch "power-domains" property is only used before & after reconfiguration but external-fpga-config FPGA region may need no reconfiguration. > > > Another case is the fpga-region may need multiple power domains? > > > > In our use case full region and relevant partial regions have different power domains and > this patch is capable of handle different power domain regions (full and partial regions) If a FPGA region needs 2 or more power domains for partial reconfiguration, how could we find out and enable them all? >From the 2 cases, I see as a generic driver, there may be need to enable different power domains at different moments. And I'm afraid a simple implementation of pm_runtime_get before reconfiguration may limit the usage of "power-domains" property for of-fpga-region. Thanks, Yilun > > > Since the of-fpga-region driver is a generic fpga-region driver, we may > > investigate more for a compatible power-domain solution. > > > > Please share your thoughts here we will try to align with it. > > Regards, > Navakishore.