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

[Akash Asthana <akashast@xxxxxxxxxxxxxx>]

Hi Matthias,

On 5/9/2020 12:23 AM, Matthias Kaehlcke wrote:
> 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'.
Agree that we are not using peak_bw voting as of now but probably we may 
use it in future, currently we are using only avg_bw for our need but if 
in future power team shares some data or ask us to reduce our power 
consumption, then with help of peak_bw we can tune ICC voting where 
power and performance both can be met as per requirement.
> > +	/* 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.

Okay.

Regards,

Akash

> > +		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);
> >   }

--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,\na Linux Foundation Collaborative Project