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Subject[PATCH 1/2] spi: mediatek: add no_need_unprepare support
Date
From: Mason Zhang <Mason.Zhang@mediatek.com>

This patch add no_need_unprepare support for spi, if spi src clk is
MAIN PLL, it can keep the clk_prepare and will not cause low power
issue. So we no need do clk_prepare/clk_unprepare in runtime pm,
and it will get better performance, because clk_prepare has called
mutex lock.
In the same way,
clk_get_rate also has called mutex lock, so we moved it to spi_probe.

Signed-off-by: Mason Zhang <Mason.Zhang@mediatek.com>
---
drivers/spi/spi-mt65xx.c | 41 +++++++++++++++++++++++++++++++++-------
1 file changed, 34 insertions(+), 7 deletions(-)

diff --git a/drivers/spi/spi-mt65xx.c b/drivers/spi/spi-mt65xx.c
index 976f73b9e299..097625d7915e 100644
--- a/drivers/spi/spi-mt65xx.c
+++ b/drivers/spi/spi-mt65xx.c
@@ -90,6 +90,8 @@ struct mtk_spi_compatible {
bool enhance_timing;
/* some IC support DMA addr extension */
bool dma_ext;
+ /* some IC no need unprepare SPI clk */
+ bool no_need_unprepare;
};

struct mtk_spi {
@@ -104,6 +106,7 @@ struct mtk_spi {
struct scatterlist *tx_sgl, *rx_sgl;
u32 tx_sgl_len, rx_sgl_len;
const struct mtk_spi_compatible *dev_comp;
+ u32 spi_clk_hz;
};

static const struct mtk_spi_compatible mtk_common_compat;
@@ -135,6 +138,14 @@ static const struct mtk_spi_compatible mt8183_compat = {
.enhance_timing = true,
};

+static const struct mtk_spi_compatible mt6893_compat = {
+ .need_pad_sel = true,
+ .must_tx = true,
+ .enhance_timing = true,
+ .dma_ext = true,
+ .no_need_unprepare = true,
+};
+
/*
* A piece of default chip info unless the platform
* supplies it.
@@ -174,6 +185,9 @@ static const struct of_device_id mtk_spi_of_match[] = {
{ .compatible = "mediatek,mt8192-spi",
.data = (void *)&mt6765_compat,
},
+ { .compatible = "mediatek,mt6893-spi",
+ .data = (void *)&mt6893_compat,
+ },
{}
};
MODULE_DEVICE_TABLE(of, mtk_spi_of_match);
@@ -287,12 +301,11 @@ static void mtk_spi_set_cs(struct spi_device *spi, bool enable)
static void mtk_spi_prepare_transfer(struct spi_master *master,
struct spi_transfer *xfer)
{
- u32 spi_clk_hz, div, sck_time, reg_val;
+ u32 div, sck_time, reg_val;
struct mtk_spi *mdata = spi_master_get_devdata(master);

- spi_clk_hz = clk_get_rate(mdata->spi_clk);
- if (xfer->speed_hz < spi_clk_hz / 2)
- div = DIV_ROUND_UP(spi_clk_hz, xfer->speed_hz);
+ if (xfer->speed_hz < mdata->spi_clk_hz / 2)
+ div = DIV_ROUND_UP(mdata->spi_clk_hz, xfer->speed_hz);
else
div = 1;

@@ -789,7 +802,12 @@ static int mtk_spi_probe(struct platform_device *pdev)
goto err_put_master;
}

- clk_disable_unprepare(mdata->spi_clk);
+ mdata->spi_clk_hz = clk_get_rate(mdata->spi_clk);
+
+ if (mdata->dev_comp->no_need_unprepare)
+ clk_disable(mdata->spi_clk);
+ else
+ clk_disable_unprepare(mdata->spi_clk);

pm_runtime_enable(&pdev->dev);

@@ -857,6 +875,9 @@ static int mtk_spi_remove(struct platform_device *pdev)

mtk_spi_reset(mdata);

+ if (mdata->dev_comp->no_need_unprepare)
+ clk_unprepare(mdata->spi_clk);
+
return 0;
}

@@ -905,7 +926,10 @@ static int mtk_spi_runtime_suspend(struct device *dev)
struct spi_master *master = dev_get_drvdata(dev);
struct mtk_spi *mdata = spi_master_get_devdata(master);

- clk_disable_unprepare(mdata->spi_clk);
+ if (mdata->dev_comp->no_need_unprepare)
+ clk_disable(mdata->spi_clk);
+ else
+ clk_disable_unprepare(mdata->spi_clk);

return 0;
}
@@ -916,7 +940,10 @@ static int mtk_spi_runtime_resume(struct device *dev)
struct mtk_spi *mdata = spi_master_get_devdata(master);
int ret;

- ret = clk_prepare_enable(mdata->spi_clk);
+ if (mdata->dev_comp->no_need_unprepare)
+ ret = clk_enable(mdata->spi_clk);
+ else
+ ret = clk_prepare_enable(mdata->spi_clk);
if (ret < 0) {
dev_err(dev, "failed to enable spi_clk (%d)\n", ret);
return ret;
--
2.18.0
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