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Subject[PATCH v2 1/2] spi: spi-qcom-qspi: Avoid clock setting if not needed
Date
As per recent changes to the spi-qcom-qspi, now when we set the clock
we'll call into the interconnect framework and also call the OPP API.
Those are expensive operations. Let's avoid calling them if possible.
This has a big impact on getting transfer rates back up to where they
were (or maybe slightly better) before those patches landed.

Fixes: cff80645d6d3 ("spi: spi-qcom-qspi: Add interconnect support")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Rajendra Nayak <rnayak@codeaurora.org>
Tested-by: Rajendra Nayak <rnayak@codeaurora.org>
Reviewed-by: Mukesh Kumar Savaliya <msavaliy@codeaurora.org>
---
This applies atop the Qualcomm tree after Rajendra's ("spi:
spi-qcom-qspi: Use OPP API to set clk/perf state") patch and I'd hope
it could land there with Mark's Ack just like the patch it Fixes did.

Changes in v2:
- Return error from runtime resume if dev_pm_opp_set_rate() fails.

drivers/spi/spi-qcom-qspi.c | 41 ++++++++++++++++++++++++++++---------
1 file changed, 31 insertions(+), 10 deletions(-)

diff --git a/drivers/spi/spi-qcom-qspi.c b/drivers/spi/spi-qcom-qspi.c
index 18a59aa23ef8..8fedc605ab7f 100644
--- a/drivers/spi/spi-qcom-qspi.c
+++ b/drivers/spi/spi-qcom-qspi.c
@@ -144,6 +144,7 @@ struct qcom_qspi {
struct icc_path *icc_path_cpu_to_qspi;
struct opp_table *opp_table;
bool has_opp_table;
+ unsigned long last_speed;
/* Lock to protect data accessed by IRQs */
spinlock_t lock;
};
@@ -226,19 +227,13 @@ static void qcom_qspi_handle_err(struct spi_master *master,
spin_unlock_irqrestore(&ctrl->lock, flags);
}

-static int qcom_qspi_transfer_one(struct spi_master *master,
- struct spi_device *slv,
- struct spi_transfer *xfer)
+static int qcom_qspi_set_speed(struct qcom_qspi *ctrl, unsigned long speed_hz)
{
- struct qcom_qspi *ctrl = spi_master_get_devdata(master);
int ret;
- unsigned long speed_hz;
- unsigned long flags;
unsigned int avg_bw_cpu;

- speed_hz = slv->max_speed_hz;
- if (xfer->speed_hz)
- speed_hz = xfer->speed_hz;
+ if (speed_hz == ctrl->last_speed)
+ return 0;

/* In regular operation (SBL_EN=1) core must be 4x transfer clock */
ret = dev_pm_opp_set_rate(ctrl->dev, speed_hz * 4);
@@ -259,6 +254,28 @@ static int qcom_qspi_transfer_one(struct spi_master *master,
return ret;
}

+ ctrl->last_speed = speed_hz;
+
+ return 0;
+}
+
+static int qcom_qspi_transfer_one(struct spi_master *master,
+ struct spi_device *slv,
+ struct spi_transfer *xfer)
+{
+ struct qcom_qspi *ctrl = spi_master_get_devdata(master);
+ int ret;
+ unsigned long speed_hz;
+ unsigned long flags;
+
+ speed_hz = slv->max_speed_hz;
+ if (xfer->speed_hz)
+ speed_hz = xfer->speed_hz;
+
+ ret = qcom_qspi_set_speed(ctrl, speed_hz);
+ if (ret)
+ return ret;
+
spin_lock_irqsave(&ctrl->lock, flags);

/* We are half duplex, so either rx or tx will be set */
@@ -602,7 +619,11 @@ static int __maybe_unused qcom_qspi_runtime_resume(struct device *dev)
return ret;
}

- return clk_bulk_prepare_enable(QSPI_NUM_CLKS, ctrl->clks);
+ ret = clk_bulk_prepare_enable(QSPI_NUM_CLKS, ctrl->clks);
+ if (ret)
+ return ret;
+
+ return dev_pm_opp_set_rate(dev, ctrl->last_speed * 4);
}

static int __maybe_unused qcom_qspi_suspend(struct device *dev)
--
2.27.0.383.g050319c2ae-goog
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