Re: [PATCH v2 09/13] i3c: dw-i3c-master: Add a quirk to skip clock and reset

Frank Li
2026-04-10T02:45:22Z

On Thu, Apr 09, 2026 at 04:27:39PM +0530, Akhil R wrote:
> Some ACPI-enumerated devices like Tegra410 do not have clock and reset
> resources exposed via the clk/reset frameworks. Add a match data for

why not export fix clock at ACPI?

> such devices to skip acquiring clock and reset controls during probe.
>
> Move match data parsing before clock/reset acquisition so the quirk is
> available early enough. When the quirk is set, fall back to reading
> the clock rate from the "clock-frequency" device property instead.

"clock-frequency" is legacy proptery.

Frank

>
> Signed-off-by: Akhil R <akhilrajeev@nvidia.com>
> ---
> drivers/i3c/master/dw-i3c-master.c | 60 +++++++++++++++++++-----------
> 1 file changed, 39 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/i3c/master/dw-i3c-master.c b/drivers/i3c/master/dw-i3c-master.c
> index 05ccdf177b6d..a62eec6d2ac0 100644
> --- a/drivers/i3c/master/dw-i3c-master.c
> +++ b/drivers/i3c/master/dw-i3c-master.c
> @@ -241,6 +241,7 @@
> /* List of quirks */
> #define AMD_I3C_OD_PP_TIMING BIT(1)
> #define DW_I3C_DISABLE_RUNTIME_PM_QUIRK BIT(2)
> +#define DW_I3C_ACPI_SKIP_CLK_RST BIT(3)
>
> struct dw_i3c_cmd {
> u32 cmd_lo;
> @@ -560,13 +561,26 @@ static void dw_i3c_master_set_intr_regs(struct dw_i3c_master *master)
> writel(IBI_REQ_REJECT_ALL, master->regs + IBI_MR_REQ_REJECT);
> }
>
> +static unsigned long dw_i3c_master_get_core_rate(struct dw_i3c_master *master)
> +{
> + unsigned int core_rate_prop;
> +
> + if (!(master->quirks & DW_I3C_ACPI_SKIP_CLK_RST))
> + return clk_get_rate(master->core_clk);
> +
> + if (device_property_read_u32(master->dev, "clock-frequency", &core_rate_prop))
> + return 0;
> +
> + return core_rate_prop;
> +}
> +
> static int dw_i3c_clk_cfg(struct dw_i3c_master *master)
> {
> unsigned long core_rate, core_period;
> u32 scl_timing;
> u8 hcnt, lcnt;
>
> - core_rate = clk_get_rate(master->core_clk);
> + core_rate = dw_i3c_master_get_core_rate(master);
> if (!core_rate)
> return -EINVAL;
>
> @@ -619,7 +633,7 @@ static int dw_i2c_clk_cfg(struct dw_i3c_master *master)
> u16 hcnt, lcnt;
> u32 scl_timing;
>
> - core_rate = clk_get_rate(master->core_clk);
> + core_rate = dw_i3c_master_get_core_rate(master);
> if (!core_rate)
> return -EINVAL;
>
> @@ -1600,21 +1614,34 @@ int dw_i3c_common_probe(struct dw_i3c_master *master,
> if (IS_ERR(master->regs))
> return PTR_ERR(master->regs);
>
> - master->core_clk = devm_clk_get_enabled(&pdev->dev, NULL);
> - if (IS_ERR(master->core_clk))
> - return PTR_ERR(master->core_clk);
> + if (has_acpi_companion(&pdev->dev)) {
> + quirks = (unsigned long)device_get_match_data(&pdev->dev);
> + } else if (pdev->dev.of_node) {
> + drvdata = device_get_match_data(&pdev->dev);
> + if (drvdata)
> + quirks = drvdata->flags;
> + }
> + master->quirks = quirks;
> +
> + if (master->quirks & DW_I3C_ACPI_SKIP_CLK_RST) {
> + master->core_clk = NULL;
> + master->core_rst = NULL;
> + } else {
> + master->core_clk = devm_clk_get_enabled(&pdev->dev, NULL);
> + if (IS_ERR(master->core_clk))
> + return PTR_ERR(master->core_clk);
> +
> + master->core_rst = devm_reset_control_get_optional_exclusive(&pdev->dev,
> + "core_rst");
> + if (IS_ERR(master->core_rst))
> + return PTR_ERR(master->core_rst);
> + reset_control_deassert(master->core_rst);
> + }
>
> master->pclk = devm_clk_get_optional_enabled(&pdev->dev, "pclk");
> if (IS_ERR(master->pclk))
> return PTR_ERR(master->pclk);
>
> - master->core_rst = devm_reset_control_get_optional_exclusive(&pdev->dev,
> - "core_rst");
> - if (IS_ERR(master->core_rst))
> - return PTR_ERR(master->core_rst);
> -
> - reset_control_deassert(master->core_rst);
> -
> spin_lock_init(&master->xferqueue.lock);
> INIT_LIST_HEAD(&master->xferqueue.list);
>
> @@ -1647,15 +1674,6 @@ int dw_i3c_common_probe(struct dw_i3c_master *master,
> master->maxdevs = ret >> 16;
> master->free_pos = GENMASK(master->maxdevs - 1, 0);
>
> - if (has_acpi_companion(&pdev->dev)) {
> - quirks = (unsigned long)device_get_match_data(&pdev->dev);
> - } else if (pdev->dev.of_node) {
> - drvdata = device_get_match_data(&pdev->dev);
> - if (drvdata)
> - quirks = drvdata->flags;
> - }
> - master->quirks = quirks;
> -
> /* Keep controller enabled by preventing runtime suspend */
> if (master->quirks & DW_I3C_DISABLE_RUNTIME_PM_QUIRK)
> pm_runtime_get_noresume(&pdev->dev);
> --
> 2.50.1
>