Re: [PATCH 4/5] i2c: qcom-cci: Add OPP table support and enforce FAST_PLUS requirements

Bryan O'Donoghue
2025-09-04T14:55:15Z

On 04/09/2025 15:31, Konrad Dybcio wrote:
> From: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
>
> The CCI clock has voltage requirements, which need to be described
> through an OPP table.
>
> The 1 MHz FAST_PLUS mode requires the CCI core clock runs at 37,5 MHz
> (which is a value common across all SoCs), since it's not possible to
> reach the required timings with the default 19.2 MHz rate.
>
> Address both issues by introducing an OPP table and using it to vote
> for the faster rate.
>
> Signed-off-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
> ---
> drivers/i2c/busses/i2c-qcom-cci.c | 33 +++++++++++++++++++++++++++++++++
> 1 file changed, 33 insertions(+)
>
> diff --git a/drivers/i2c/busses/i2c-qcom-cci.c b/drivers/i2c/busses/i2c-qcom-cci.c
> index 74fedfdec3ae4e034ec4d946179e963c783b5923..d6192e2a5e3bc4d908cba594d1910a41f3a41e9c 100644
> --- a/drivers/i2c/busses/i2c-qcom-cci.c
> +++ b/drivers/i2c/busses/i2c-qcom-cci.c
> @@ -10,6 +10,7 @@
> #include <linux/module.h>
> #include <linux/of.h>
> #include <linux/platform_device.h>
> +#include <linux/pm_opp.h>
> #include <linux/pm_runtime.h>
>
> #define CCI_HW_VERSION 0x0
> @@ -121,6 +122,7 @@ struct cci_data {
> struct i2c_adapter_quirks quirks;
> u16 queue_size[NUM_QUEUES];
> struct hw_params params[3];
> + bool fast_mode_plus_supported;

that is a very long name for a flag

> };
>
> struct cci {
> @@ -466,9 +468,22 @@ static const struct i2c_algorithm cci_algo = {
> .functionality = cci_func,
> };
>
> +static unsigned long cci_desired_clk_rate(struct cci *cci)
> +{
> + if (cci->data->fast_mode_plus_supported)
> + return 37500000ULL;
> +
> + return 19200000ULL;

what's 32 bits between friends ?

> +}
> +
> static int __maybe_unused cci_suspend_runtime(struct device *dev)
> {
> struct cci *cci = dev_get_drvdata(dev);
> + int ret;
> +
> + ret = dev_pm_opp_set_rate(dev, 0);
> + if (ret)
> + return ret;
>
> clk_bulk_disable_unprepare(cci->nclocks, cci->clocks);
>
> @@ -484,6 +499,10 @@ static int __maybe_unused cci_resume_runtime(struct device *dev)
> if (ret)
> return ret;
>
> + ret = dev_pm_opp_set_rate(dev, cci_desired_clk_rate(cci));
> + if (ret)
> + return ret;
> +
> cci_init(cci);
>
> return 0;
> @@ -588,6 +607,19 @@ static int cci_probe(struct platform_device *pdev)
> if (ret < 0)
> return ret;
>
> + ret = devm_pm_opp_set_clkname(dev, "cci");
> + if (ret)
> + return ret;
> +
> + /* OPP table is optional */
> + ret = devm_pm_opp_of_add_table(dev);
> + if (ret && ret != -ENODEV)
> + return dev_err_probe(dev, ret, "invalid OPP table in device tree\n");
> +
> + ret = dev_pm_opp_set_rate(dev, cci_desired_clk_rate(cci));
> + if (ret)
> + return ret;
> +
> /* Interrupt */
>
> ret = platform_get_irq(pdev, 0);
> @@ -775,6 +807,7 @@ static const struct cci_data cci_v2_data = {
> .trdhld = 3,
> .tsp = 3
> },
> + .fast_mode_plus_supported = true,
> };
>
> static const struct of_device_id cci_dt_match[] = {
>

LGTM

Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>