Re: [PATCH V5 6/7] spi: spi-qcom-qspi: Add interconnect support

[Matthias Kaehlcke <mka@xxxxxxxxxxxx>]

On Fri, May 08, 2020 at 12:03:38PM +0530, Akash Asthana wrote:
> Get the interconnect paths for QSPI device and vote according to the
> current bus speed of the driver.
> 
> Signed-off-by: Akash Asthana <akashast@xxxxxxxxxxxxxx>
> ---
> Changes in V2:
>  - As per Bjorn's comment, introduced and using devm_of_icc_get API for getting
>    path handle
>  - As per Matthias comment, added error handling for icc_set_bw call
> 
> Changes in V3:
>  - No Change.
> 
> Changes in V4:
>  - As per Mark's comment move peak_bw guess as twice of avg_bw if
>    nothing mentioned explicitly to ICC core.
> 
> Changes in V5:
>  - Add icc_enable/disable to power on/off call.
>  - Save some non-zero avg/peak value to ICC core by calling geni_icc_set_bw
>    from probe so that when resume/icc_enable is called NOC are running at
>    some non-zero value.
> 
>  drivers/spi/spi-qcom-qspi.c | 59 ++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 58 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/spi/spi-qcom-qspi.c b/drivers/spi/spi-qcom-qspi.c
> index 3c4f83b..6e299f4 100644
> --- a/drivers/spi/spi-qcom-qspi.c
> +++ b/drivers/spi/spi-qcom-qspi.c
> @@ -2,6 +2,7 @@
>  // Copyright (c) 2017-2018, The Linux foundation. All rights reserved.
>  
>  #include <linux/clk.h>
> +#include <linux/interconnect.h>
>  #include <linux/interrupt.h>
>  #include <linux/io.h>
>  #include <linux/module.h>
> @@ -139,7 +140,10 @@ struct qcom_qspi {
>  	struct device *dev;
>  	struct clk_bulk_data *clks;
>  	struct qspi_xfer xfer;
> -	/* Lock to protect xfer and IRQ accessed registers */
> +	struct icc_path *icc_path_cpu_to_qspi;
> +	unsigned int avg_bw_cpu;
> +	unsigned int peak_bw_cpu;

There is no point in having two fields, 'peak_bw_cpu' is always assigned
to 'avg_bw_cpu' and passed to icc_set_bw(). Just make it a single field
'icc_bw_cpu'.

> +	/* Lock to protect data accessed by IRQs */
>  	spinlock_t lock;
>  };
>  
> @@ -241,6 +245,20 @@ static int qcom_qspi_transfer_one(struct spi_master *master,
>  		return ret;
>  	}
>  
> +	/*
> +	 * Set BW quota for CPU as driver supports FIFO mode only.
> +	 * We don't have explicit peak requirement so keep it equal to avg_bw.
> +	 */
> +	ctrl->avg_bw_cpu = Bps_to_icc(speed_hz);
> +	ctrl->peak_bw_cpu = ctrl->avg_bw_cpu;
> +	ret = icc_set_bw(ctrl->icc_path_cpu_to_qspi, ctrl->avg_bw_cpu,
> +		ctrl->peak_bw_cpu);
> +	if (ret) {
> +		dev_err(ctrl->dev, "%s: ICC BW voting failed for cpu\n",
> +			__func__);

the logging in this patch is inconsistent. Here the error is not printed,
at all, in other cases it's "<error>, ret:-42" or "<error> ret:-42".
Please stick to a common format (unless there is no error). My
suggestion would be "<error>: -42", in my perception "ret:" just adds
noise.

> +		return ret;
> +	}
> +
>  	spin_lock_irqsave(&ctrl->lock, flags);
>  
>  	/* We are half duplex, so either rx or tx will be set */
> @@ -458,6 +476,29 @@ static int qcom_qspi_probe(struct platform_device *pdev)
>  	if (ret)
>  		goto exit_probe_master_put;
>  
> +	ctrl->icc_path_cpu_to_qspi = devm_of_icc_get(dev, "qspi-config");
> +	if (IS_ERR(ctrl->icc_path_cpu_to_qspi)) {
> +		ret = PTR_ERR(ctrl->icc_path_cpu_to_qspi);
> +		if (ret != -EPROBE_DEFER)
> +			dev_err(dev, "Failed to get cpu path, ret:%d\n", ret);
> +		goto exit_probe_master_put;
> +	}
> +	/* Set BW vote for register access */
> +	ret = icc_set_bw(ctrl->icc_path_cpu_to_qspi, Bps_to_icc(1000),
> +				Bps_to_icc(1000));
> +	if (ret) {
> +		dev_err(ctrl->dev, "%s: ICC BW voting failed for cpu ret:%d\n",
> +				__func__, ret);
> +		goto exit_probe_master_put;
> +	}
> +
> +	ret = icc_disable(ctrl->icc_path_cpu_to_qspi);
> +	if (ret) {
> +		dev_err(ctrl->dev, "%s: ICC disable failed for cpu ret:%d\n",
> +				__func__, ret);
> +		goto exit_probe_master_put;
> +	}
> +
>  	ret = platform_get_irq(pdev, 0);
>  	if (ret < 0)
>  		goto exit_probe_master_put;
> @@ -511,9 +552,17 @@ static int __maybe_unused qcom_qspi_runtime_suspend(struct device *dev)
>  {
>  	struct spi_master *master = dev_get_drvdata(dev);
>  	struct qcom_qspi *ctrl = spi_master_get_devdata(master);
> +	int ret;
>  
>  	clk_bulk_disable_unprepare(QSPI_NUM_CLKS, ctrl->clks);
>  
> +	ret = icc_disable(ctrl->icc_path_cpu_to_qspi);
> +	if (ret) {
> +		dev_err_ratelimited(ctrl->dev, "%s: ICC disable failed for cpu ret:%d\n",
> +			__func__, ret);
> +		return ret;
> +	}
> +
>  	return 0;
>  }
>  
> @@ -521,6 +570,14 @@ static int __maybe_unused qcom_qspi_runtime_resume(struct device *dev)
>  {
>  	struct spi_master *master = dev_get_drvdata(dev);
>  	struct qcom_qspi *ctrl = spi_master_get_devdata(master);
> +	int ret;
> +
> +	ret = icc_enable(ctrl->icc_path_cpu_to_qspi);
> +	if (ret) {
> +		dev_err_ratelimited(ctrl->dev, "%s: ICC enable failed for cpu ret:%d\n",
> +			__func__, ret);
> +		return ret;
> +	}
>  
>  	return clk_bulk_prepare_enable(QSPI_NUM_CLKS, ctrl->clks);
>  }