> -----Original Message----- > From: Frank Li <frank.li@xxxxxxx> > Sent: 2025年6月20日 22:41 > To: Krzysztof Kozlowski <krzk@xxxxxxxxxx> > Cc: Hongxing Zhu <hongxing.zhu@xxxxxxx>; l.stach@xxxxxxxxxxxxxx; > lpieralisi@xxxxxxxxxx; kwilczynski@xxxxxxxxxx; mani@xxxxxxxxxx; > robh@xxxxxxxxxx; krzk+dt@xxxxxxxxxx; conor+dt@xxxxxxxxxx; > bhelgaas@xxxxxxxxxx; shawnguo@xxxxxxxxxx; s.hauer@xxxxxxxxxxxxxx; > kernel@xxxxxxxxxxxxxx; festevam@xxxxxxxxx; linux-pci@xxxxxxxxxxxxxxx; > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx; > imx@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx > Subject: Re: [PATCH v3 1/2] dt-binding: pci-imx6: Add external reference clock > mode support > > On Fri, Jun 20, 2025 at 03:08:16PM +0200, Krzysztof Kozlowski wrote: > > On 20/06/2025 10:26, Hongxing Zhu wrote: > > >> -----Original Message----- > > >> From: Krzysztof Kozlowski <krzk@xxxxxxxxxx> > > >> Sent: 2025年6月20日 15:53 > > >> To: Hongxing Zhu <hongxing.zhu@xxxxxxx> > > >> Cc: Frank Li <frank.li@xxxxxxx>; l.stach@xxxxxxxxxxxxxx; > > >> lpieralisi@xxxxxxxxxx; kwilczynski@xxxxxxxxxx; mani@xxxxxxxxxx; > > >> robh@xxxxxxxxxx; krzk+dt@xxxxxxxxxx; conor+dt@xxxxxxxxxx; > > >> bhelgaas@xxxxxxxxxx; shawnguo@xxxxxxxxxx; s.hauer@xxxxxxxxxxxxxx; > > >> kernel@xxxxxxxxxxxxxx; festevam@xxxxxxxxx; > > >> linux-pci@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; > > >> devicetree@xxxxxxxxxxxxxxx; imx@xxxxxxxxxxxxxxx; > > >> linux-kernel@xxxxxxxxxxxxxxx > > >> Subject: Re: [PATCH v3 1/2] dt-binding: pci-imx6: Add external > > >> reference clock mode support > > >> > > >> On Fri, Jun 20, 2025 at 11:13:49AM GMT, Richard Zhu wrote: > > >>> On i.MX, the PCIe reference clock might come from either internal > > >>> system PLL or external clock source. > > >>> Add the external reference clock source for reference clock. > > >>> > > >>> Signed-off-by: Richard Zhu <hongxing.zhu@xxxxxxx> > > >>> Reviewed-by: Frank Li <Frank.Li@xxxxxxx> > > >>> --- > > >>> Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.yaml | 7 > > >>> ++++++- > > >>> 1 file changed, 6 insertions(+), 1 deletion(-) > > >>> > > >>> diff --git > > >>> a/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.yaml > > >>> b/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.yaml > > >>> index ca5f2970f217..c472a5daae6e 100644 > > >>> --- a/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.yaml > > >>> +++ b/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.yaml > > >>> @@ -219,7 +219,12 @@ allOf: > > >>> - const: pcie_bus > > >>> - const: pcie_phy > > >>> - const: pcie_aux > > >>> - - const: ref > > >>> + - description: PCIe reference clock. > > >>> + oneOf: > > >>> + - description: The controller might be configured > > >> clocking > > >>> + coming in from either an internal system PLL > > >>> + or > > >> an > > >>> + external clock source. > > >>> + enum: [ref, gio] > > >> > > >> Internal like within PCIe or coming from other SoC block? What does "gio" > > >> mean? > > > Internal means that the PCIe reference clock is coming from other > > > internal SoC block, such as system PLL. "gio" is on behalf that the > > > reference clock comes form external crystal oscillator. > > > > Then what does "ref" mean, if gio is the clock supplied externally? > > In snps,dw-pcie-common.yaml > > - description: > Generic reference clock. In case if there are several > interfaces fed up with a common clock source it's advisable to > define it with this name (for instance pipe, core and aux can > be connected to a single source of the periodic signal). > const: ref > > - description: See native 'ref' clock for details. > enum: [ gio ] > > We > > talk here about signals coming to this chip, regardless how they are > > generated. > > PCIe controller takes one of two reference clocks, internal PLL (controlled by > clock provider) and extern crystal (controller by a GPIO). > > There are clk_in and clk_out at SOC. External crystal output connect into clk_in. > > clk_out come from internal pll. > > The boards design choose one method (internal pll or use external crystal) That's right. Thanks. Best Regards Richard Zhu > > Frank > > > > > > > Best regards, > > Krzysztof
