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

[Akash Asthana <akashast@codeaurora.org>]

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@codeaurora.org>
>> ---
>> 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);
>>   }

-- 
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