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    SubjectRe: [PATCH 1/5] i2c: i2c-stm32f7: disable/restore Fast Mode Plus bits in low power modes
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    Hello

    Reviewed-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>

    Thanks

    On 1/23/20 5:12 PM, Alain Volmat wrote:
    > Defer the initial enabling of the Fast Mode Plus bits after the
    > stm32f7_i2c_setup_timing call in probe function in order to avoid
    > enabling them if speed is downgraded.
    > Clear & restore the Fast Mode Plus bits in the suspend/resume
    > handlers of the driver.
    >
    > Signed-off-by: Alain Volmat <alain.volmat@st.com>
    > ---
    > drivers/i2c/busses/i2c-stm32f7.c | 48 +++++++++++++++++++++++++++++++++-------
    > 1 file changed, 40 insertions(+), 8 deletions(-)
    >
    > diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
    > index 844a22d64aa8..1a3b3fa582ff 100644
    > --- a/drivers/i2c/busses/i2c-stm32f7.c
    > +++ b/drivers/i2c/busses/i2c-stm32f7.c
    > @@ -303,6 +303,8 @@ struct stm32f7_i2c_msg {
    > * @dma: dma data
    > * @use_dma: boolean to know if dma is used in the current transfer
    > * @regmap: holds SYSCFG phandle for Fast Mode Plus bits
    > + * @regmap_reg: register address for setting Fast Mode Plus bits
    > + * @regmap_mask: mask for Fast Mode Plus bits in set register
    > * @wakeup_src: boolean to know if the device is a wakeup source
    > */
    > struct stm32f7_i2c_dev {
    > @@ -326,6 +328,8 @@ struct stm32f7_i2c_dev {
    > struct stm32_i2c_dma *dma;
    > bool use_dma;
    > struct regmap *regmap;
    > + u32 regmap_reg;
    > + u32 regmap_mask;
    > bool wakeup_src;
    > };
    >
    > @@ -1815,12 +1819,25 @@ static int stm32f7_i2c_unreg_slave(struct i2c_client *slave)
    > return 0;
    > }
    >
    > +static int stm32f7_i2c_write_fm_plus_bits(struct stm32f7_i2c_dev *i2c_dev,
    > + bool enable)
    > +{
    > + if (i2c_dev->speed != STM32_I2C_SPEED_FAST_PLUS ||
    > + IS_ERR_OR_NULL(i2c_dev->regmap)) {
    > + /* Optional */
    > + return 0;
    > + }
    > +
    > + return regmap_update_bits(i2c_dev->regmap, i2c_dev->regmap_reg,
    > + i2c_dev->regmap_mask,
    > + enable ? i2c_dev->regmap_mask : 0);
    > +}
    > +
    > static int stm32f7_i2c_setup_fm_plus_bits(struct platform_device *pdev,
    > struct stm32f7_i2c_dev *i2c_dev)
    > {
    > struct device_node *np = pdev->dev.of_node;
    > int ret;
    > - u32 reg, mask;
    >
    > i2c_dev->regmap = syscon_regmap_lookup_by_phandle(np, "st,syscfg-fmp");
    > if (IS_ERR(i2c_dev->regmap)) {
    > @@ -1828,15 +1845,17 @@ static int stm32f7_i2c_setup_fm_plus_bits(struct platform_device *pdev,
    > return 0;
    > }
    >
    > - ret = of_property_read_u32_index(np, "st,syscfg-fmp", 1, &reg);
    > + ret = of_property_read_u32_index(np, "st,syscfg-fmp", 1,
    > + &i2c_dev->regmap_reg);
    > if (ret)
    > return ret;
    >
    > - ret = of_property_read_u32_index(np, "st,syscfg-fmp", 2, &mask);
    > + ret = of_property_read_u32_index(np, "st,syscfg-fmp", 2,
    > + &i2c_dev->regmap_mask);
    > if (ret)
    > return ret;
    >
    > - return regmap_update_bits(i2c_dev->regmap, reg, mask, mask);
    > + return 0;
    > }
    >
    > static u32 stm32f7_i2c_func(struct i2c_adapter *adap)
    > @@ -1914,9 +1933,6 @@ static int stm32f7_i2c_probe(struct platform_device *pdev)
    > &clk_rate);
    > if (!ret && clk_rate >= 1000000) {
    > i2c_dev->speed = STM32_I2C_SPEED_FAST_PLUS;
    > - ret = stm32f7_i2c_setup_fm_plus_bits(pdev, i2c_dev);
    > - if (ret)
    > - goto clk_free;
    > } else if (!ret && clk_rate >= 400000) {
    > i2c_dev->speed = STM32_I2C_SPEED_FAST;
    > } else if (!ret && clk_rate >= 100000) {
    > @@ -1976,6 +1992,15 @@ static int stm32f7_i2c_probe(struct platform_device *pdev)
    > if (ret)
    > goto clk_free;
    >
    > + if (i2c_dev->speed == STM32_I2C_SPEED_FAST_PLUS) {
    > + ret = stm32f7_i2c_setup_fm_plus_bits(pdev, i2c_dev);
    > + if (ret)
    > + goto clk_free;
    > + ret = stm32f7_i2c_write_fm_plus_bits(i2c_dev, 1);
    > + if (ret)
    > + goto clk_free;
    > + }
    > +
    > adap = &i2c_dev->adap;
    > i2c_set_adapdata(adap, i2c_dev);
    > snprintf(adap->name, sizeof(adap->name), "STM32F7 I2C(%pa)",
    > @@ -2000,7 +2025,7 @@ static int stm32f7_i2c_probe(struct platform_device *pdev)
    > if (ret != -EPROBE_DEFER)
    > dev_err(&pdev->dev,
    > "Failed to request dma error %i\n", ret);
    > - goto clk_free;
    > + goto fmp_clear;
    > }
    >
    > if (i2c_dev->wakeup_src) {
    > @@ -2054,6 +2079,9 @@ static int stm32f7_i2c_probe(struct platform_device *pdev)
    > i2c_dev->dma = NULL;
    > }
    >
    > +fmp_clear:
    > + stm32f7_i2c_write_fm_plus_bits(i2c_dev, 0);
    > +
    > clk_free:
    > clk_disable_unprepare(i2c_dev->clk);
    >
    > @@ -2086,6 +2114,8 @@ static int stm32f7_i2c_remove(struct platform_device *pdev)
    > i2c_dev->dma = NULL;
    > }
    >
    > + stm32f7_i2c_write_fm_plus_bits(i2c_dev, 0);
    > +
    > clk_disable_unprepare(i2c_dev->clk);
    >
    > return 0;
    > @@ -2133,6 +2163,7 @@ stm32f7_i2c_regs_backup(struct stm32f7_i2c_dev *i2c_dev)
    > backup_regs->oar2 = readl_relaxed(i2c_dev->base + STM32F7_I2C_OAR2);
    > backup_regs->pecr = readl_relaxed(i2c_dev->base + STM32F7_I2C_PECR);
    > backup_regs->tmgr = readl_relaxed(i2c_dev->base + STM32F7_I2C_TIMINGR);
    > + stm32f7_i2c_write_fm_plus_bits(i2c_dev, 0);
    >
    > pm_runtime_put_sync(i2c_dev->dev);
    >
    > @@ -2165,6 +2196,7 @@ stm32f7_i2c_regs_restore(struct stm32f7_i2c_dev *i2c_dev)
    > writel_relaxed(backup_regs->oar1, i2c_dev->base + STM32F7_I2C_OAR1);
    > writel_relaxed(backup_regs->oar2, i2c_dev->base + STM32F7_I2C_OAR2);
    > writel_relaxed(backup_regs->pecr, i2c_dev->base + STM32F7_I2C_PECR);
    > + stm32f7_i2c_write_fm_plus_bits(i2c_dev, 1);
    >
    > pm_runtime_put_sync(i2c_dev->dev);
    >
    >

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