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    SubjectRe: [PATCH v5 4/4] PCI: qcom: Switch pcie_1_pipe_clk_src after PHY init in SC7280
    On Thu, Aug 26, 2021 at 2:22 AM Prasad Malisetty
    <pmaliset@codeaurora.org> wrote:
    >
    > On 2021-08-26 02:55, Bjorn Helgaas wrote:
    > > [+cc linux-pci; patches to drivers/pci/ should always be cc'd there]
    > >
    > > On Wed, Aug 25, 2021 at 07:30:09PM +0000, Stephen Boyd wrote:
    > >> Quoting Prasad Malisetty (2021-08-24 01:10:48)
    > >> > On 2021-08-17 22:56, Prasad Malisetty wrote:
    > >> > > On 2021-08-10 09:38, Prasad Malisetty wrote:
    > >> > >> On the SC7280, By default the clock source for pcie_1_pipe is
    > >> > >> TCXO for gdsc enable. But after the PHY is initialized, the clock
    > >> > >> source must be switched to gcc_pcie_1_pipe_clk from TCXO.
    > >> > >>
    > >> > >> Signed-off-by: Prasad Malisetty <pmaliset@codeaurora.org>
    > >> > >> ---
    > >> > >> drivers/pci/controller/dwc/pcie-qcom.c | 18 ++++++++++++++++++
    > >> > >> 1 file changed, 18 insertions(+)
    > >> > >>
    > >> > >> diff --git a/drivers/pci/controller/dwc/pcie-qcom.c
    > >> > >> b/drivers/pci/controller/dwc/pcie-qcom.c
    > >> > >> index 8a7a300..39e3b21 100644
    > >> > >> --- a/drivers/pci/controller/dwc/pcie-qcom.c
    > >> > >> +++ b/drivers/pci/controller/dwc/pcie-qcom.c
    > >> > >> @@ -166,6 +166,8 @@ struct qcom_pcie_resources_2_7_0 {
    > >> > >> struct regulator_bulk_data supplies[2];
    > >> > >> struct reset_control *pci_reset;
    > >> > >> struct clk *pipe_clk;
    > >> > >> + struct clk *gcc_pcie_1_pipe_clk_src;
    > >> > >> + struct clk *phy_pipe_clk;
    > >> > >> };
    > >> > >>
    > >> > >> union qcom_pcie_resources {
    > >> > >> @@ -1167,6 +1169,16 @@ static int qcom_pcie_get_resources_2_7_0(struct
    > >> > >> qcom_pcie *pcie)
    > >> > >> if (ret < 0)
    > >> > >> return ret;
    > >> > >>
    > >> > >> + if (of_device_is_compatible(dev->of_node, "qcom,pcie-sc7280")) {
    > >> > >> + res->gcc_pcie_1_pipe_clk_src = devm_clk_get(dev, "pipe_mux");
    > >> > >> + if (IS_ERR(res->gcc_pcie_1_pipe_clk_src))
    > >> > >> + return PTR_ERR(res->gcc_pcie_1_pipe_clk_src);
    > >> > >> +
    > >> > >> + res->phy_pipe_clk = devm_clk_get(dev, "phy_pipe");
    > >> > >> + if (IS_ERR(res->phy_pipe_clk))
    > >> > >> + return PTR_ERR(res->phy_pipe_clk);
    > >> > >> + }
    > >> > >
    > >> > > I would like to check is there any other better approach instead of
    > >> > > compatible method here as well or is it fine to use compatible method.
    > >>
    > >> I'd prefer the compatible method. If nobody is responding then it's
    > >> best
    > >> to just resend the patches with the approach you prefer instead of
    > >> waiting for someone to respond to a review comment.
    > >
    > > I'm missing some context here, so I'm not exactly sure what your
    > > question is, Prasad, but IMO drivers generally should not need to use
    > > of_device_is_compatible() if they've already called
    > > of_device_get_match_data() (as qcom_pcie_probe() has).
    > >
    > > of_device_is_compatible() does basically the same work of looking for
    > > a match in qcom_pcie_match[] that of_device_get_match_data() does, so
    > > it seems pointless to repeat it.

    +1

    > > I am a little confused because while [1] adds "qcom,pcie-sc7280" to
    > > qcom,pcie.txt, I don't see a patch that adds it to qcom_pcie_match[].

    Either that's missing or there's a fallback to 8250 that's not documented.
    > >
    > > Bjorn
    > >
    > Hi Bjorn,
    >
    > I agree on your point, but the main reason is to use compatible in
    > get_resources_2_7_0 is same hardware version. For SM8250 & SC7280
    > platforms, the hw version is same. Since we can't have a separate ops
    > for SC7280, we are using compatible method in get_resources_2_7_0 to
    > differentiate SM8250 and SC7280.

    Then fix the match data to be not just ops, but ops and the flag you need here.

    Rob

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