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

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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



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