Re: [PATCH v5 4/4] PCI: qcom: Switch pcie_1_pipe_clk_src after PHY init in SC7280

[Prasad Malisetty]

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@xxxxxxxxxxxxxx>
> > > >> ---
> > > >>  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.
>
> 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[].
>
> 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.

Thanks
-Prasad
> [1]
> https://lore.kernel.org/linux-arm-msm/1628568516-24155-2-git-send-email-pmaliset@xxxxxxxxxxxxxx/