Re: [PATCH v5 4/4] PCI: qcom: Switch pcie_1_pipe_clk_src after PHY init in SC7280
From: Prasad Malisetty
Date: Tue Aug 31 2021 - 02:37:42 EST
On 2021-08-26 18:07, Rob Herring wrote:
On Thu, Aug 26, 2021 at 2:22 AM Prasad Malisetty
<pmaliset@xxxxxxxxxxxxxx> 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@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.
+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
Hi Rob,
Thanks for your review comments and inputs .
This difference is not universal across all the platforms but instead
this is specific to SC7280.
Hence it make sense to use compatible other than going for a flag.
Thanks
-Prasad