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

[Frank Li <Frank.li@nxp.com>]

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
>