Re: [PATCH v6 02/10] PCI: imx6: Add ref clock for i.MX95 PCIe

Manivannan Sadhasivam
2024-11-15T06:38:27Z

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"?

> 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@nxp.com>
> Reviewed-by: Frank Li <Frank.Li@nxp.com>
> ---
> 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")

And who is going to supply the reference clock in the absence of this clockn in
DT?

- 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
>

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