> -----Original Message-----
> From: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
> Sent: 2024年11月15日 14:38
> To: Hongxing Zhu <hongxing.zhu@xxxxxxx>
> Cc: l.stach@xxxxxxxxxxxxxx; bhelgaas@xxxxxxxxxx; lpieralisi@xxxxxxxxxx;
> kw@xxxxxxxxx; robh@xxxxxxxxxx; krzk+dt@xxxxxxxxxx; conor+dt@xxxxxxxxxx;
> shawnguo@xxxxxxxxxx; Frank Li <frank.li@xxxxxxx>;
> s.hauer@xxxxxxxxxxxxxx; festevam@xxxxxxxxx; imx@xxxxxxxxxxxxxxx;
> kernel@xxxxxxxxxxxxxx; linux-pci@xxxxxxxxxxxxxxx;
> linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx;
> linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH v6 02/10] PCI: imx6: Add ref clock for i.MX95 PCIe
>
> On Fri, Nov 01, 2024 at 03:06:02PM +0800, Richard Zhu wrote:
> > Add "ref" clock to enable reference clock. To avoid the DT
> > compatibility, i.MX95 REF clock might be optional.
>
> Your wording is not correct. Perhaps you wanted to say, "To avoid breaking
> DT backwards compatibility"?
>
Yes, you're right. Thanks.
> > Replace the
> > devm_clk_bulk_get() by devm_clk_bulk_get_optional() to fetch
> > i.MX95 PCIe optional clocks in driver.
> >
> > If use external clock, ref clock should point to external reference.
> >
> > If use internal clock, CREF_EN in LAST_TO_REG controls reference
> > output, which implement in drivers/clk/imx/clk-imx95-blk-ctl.c.
> >
> > Signed-off-by: Richard Zhu <hongxing.zhu@xxxxxxx>
> > Reviewed-by: Frank Li <Frank.Li@xxxxxxx>
> > ---
> > drivers/pci/controller/dwc/pci-imx6.c | 19 +++++++++++++------
> > 1 file changed, 13 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/pci/controller/dwc/pci-imx6.c
> > b/drivers/pci/controller/dwc/pci-imx6.c
> > index 808d1f105417..bc8567677a67 100644
> > --- a/drivers/pci/controller/dwc/pci-imx6.c
> > +++ b/drivers/pci/controller/dwc/pci-imx6.c
> > @@ -82,6 +82,7 @@ enum imx_pcie_variants {
> > #define IMX_PCIE_FLAG_HAS_SERDES BIT(6)
> > #define IMX_PCIE_FLAG_SUPPORT_64BIT BIT(7)
> > #define IMX_PCIE_FLAG_CPU_ADDR_FIXUP BIT(8)
> > +#define IMX_PCIE_FLAG_CUSTOM_PME_TURNOFF BIT(9)
> >
> > #define imx_check_flag(pci, val) (pci->drvdata->flags & val)
> >
> > @@ -98,6 +99,7 @@ struct imx_pcie_drvdata {
> > const char *gpr;
> > const char * const *clk_names;
> > const u32 clks_cnt;
> > + const u32 clks_optional_cnt;
> > const u32 ltssm_off;
> > const u32 ltssm_mask;
> > const u32 mode_off[IMX_PCIE_MAX_INSTANCES]; @@ -1278,9 +1280,8
> @@
> > static int imx_pcie_probe(struct platform_device *pdev)
> > struct device_node *np;
> > struct resource *dbi_base;
> > struct device_node *node = dev->of_node;
> > - int ret;
> > + int ret, i, req_cnt;
> > u16 val;
> > - int i;
> >
> > imx_pcie = devm_kzalloc(dev, sizeof(*imx_pcie), GFP_KERNEL);
> > if (!imx_pcie)
> > @@ -1330,7 +1331,10 @@ static int imx_pcie_probe(struct
> platform_device *pdev)
> > imx_pcie->clks[i].id = imx_pcie->drvdata->clk_names[i];
> >
> > /* Fetch clocks */
> > - ret = devm_clk_bulk_get(dev, imx_pcie->drvdata->clks_cnt,
> imx_pcie->clks);
> > + req_cnt = imx_pcie->drvdata->clks_cnt -
> imx_pcie->drvdata->clks_optional_cnt;
> > + ret = devm_clk_bulk_get(dev, req_cnt, imx_pcie->clks);
> > + ret |= devm_clk_bulk_get_optional(dev,
> imx_pcie->drvdata->clks_optional_cnt,
> > + imx_pcie->clks + req_cnt);
>
> Why do you need to use 'clk_bulk' API to get a single reference clock? Just
> use devm_clk_get_optional(dev, "ref")
It's easier to add more optional clks in future. I can change to use
devm_clk_get_optional(dev, "ref") here if you insistent.
>
> And who is going to supply the reference clock in the absence of this clockn in
> DT?
When the "preview" version firmware is used, this clock is gated on in default.
In this case, hiso-blk-ctrl would gated on this clock in default state.
Best Regards
Richard Zhu
>
> - Mani
>
> > if (ret)
> > return ret;
> >
> > @@ -1480,6 +1484,7 @@ static const char * const imx8mm_clks[] =
> > {"pcie_bus", "pcie", "pcie_aux"}; static const char * const
> > imx8mq_clks[] = {"pcie_bus", "pcie", "pcie_phy", "pcie_aux"}; static
> > const char * const imx6sx_clks[] = {"pcie_bus", "pcie", "pcie_phy",
> > "pcie_inbound_axi"}; static const char * const imx8q_clks[] =
> > {"mstr", "slv", "dbi"};
> > +static const char * const imx95_clks[] = {"pcie_bus", "pcie",
> > +"pcie_phy", "pcie_aux", "ref"};
> >
> > static const struct imx_pcie_drvdata drvdata[] = {
> > [IMX6Q] = {
> > @@ -1592,9 +1597,11 @@ static const struct imx_pcie_drvdata drvdata[] =
> {
> > },
> > [IMX95] = {
> > .variant = IMX95,
> > - .flags = IMX_PCIE_FLAG_HAS_SERDES,
> > - .clk_names = imx8mq_clks,
> > - .clks_cnt = ARRAY_SIZE(imx8mq_clks),
> > + .flags = IMX_PCIE_FLAG_HAS_SERDES |
> > + IMX_PCIE_FLAG_SUPPORTS_SUSPEND,
> > + .clk_names = imx95_clks,
> > + .clks_cnt = ARRAY_SIZE(imx95_clks),
> > + .clks_optional_cnt = 1,
> > .ltssm_off = IMX95_PE0_GEN_CTRL_3,
> > .ltssm_mask = IMX95_PCIE_LTSSM_EN,
> > .mode_off[0] = IMX95_PE0_GEN_CTRL_1,
> > --
> > 2.37.1
> >
>
> --
> மணிவண்ணன் சதாசிவம்
