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i2c: imx: Avoid deadlock between clk_prepare_lock and i2c bus lock #40

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i2c: imx: Avoid deadlock between clk_prepare_lock and i2c bus lock #40

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21 changes: 18 additions & 3 deletions drivers/i2c/busses/i2c-imx.c
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Original file line number Diff line number Diff line change
Expand Up @@ -265,6 +265,7 @@ struct imx_i2c_struct {
int stopped;
unsigned int ifdr; /* IMX_I2C_IFDR */
unsigned int cur_clk;
unsigned int clk_rate;
unsigned int bitrate;
const struct imx_i2c_hwdata *hwdata;
struct i2c_bus_recovery_info rinfo;
Expand Down Expand Up @@ -711,8 +712,10 @@ static int i2c_imx_clk_notifier_call(struct notifier_block *nb,
struct imx_i2c_struct,
clk_change_nb);

if (action & POST_RATE_CHANGE)
if (action & POST_RATE_CHANGE) {
WRITE_ONCE(i2c_imx->clk_rate, ndata->new_rate);
ret = i2c_imx_set_clk(i2c_imx, ndata->new_rate);
}

return notifier_from_errno(ret);
}
Expand All @@ -722,7 +725,11 @@ static int i2c_imx_start(struct imx_i2c_struct *i2c_imx, bool atomic)
unsigned int temp = 0;
int result;

result = i2c_imx_set_clk(i2c_imx, clk_get_rate(i2c_imx->clk));
if (!READ_ONCE(i2c_imx->clk_rate))
return -EINVAL;

result = i2c_imx_set_clk(i2c_imx, READ_ONCE(i2c_imx->clk_rate));

if (result)
return result;

Expand Down Expand Up @@ -1763,7 +1770,8 @@ static int i2c_imx_probe(struct platform_device *pdev)
i2c_imx->bitrate = pdata->bitrate;
i2c_imx->clk_change_nb.notifier_call = i2c_imx_clk_notifier_call;
clk_notifier_register(i2c_imx->clk, &i2c_imx->clk_change_nb);
ret = i2c_imx_set_clk(i2c_imx, clk_get_rate(i2c_imx->clk));
WRITE_ONCE(i2c_imx->clk_rate, clk_get_rate(i2c_imx->clk));
ret = i2c_imx_set_clk(i2c_imx, READ_ONCE(i2c_imx->clk_rate));
if (ret < 0) {
dev_err(&pdev->dev, "can't get I2C clock\n");
goto clk_notifier_unregister;
Expand Down Expand Up @@ -1875,6 +1883,13 @@ static int __maybe_unused i2c_imx_runtime_resume(struct device *dev)
ret = clk_prepare_enable(i2c_imx->clk);
if (ret)
dev_err(dev, "can't enable I2C clock, ret=%d\n", ret);
else {
i2c_imx->cur_clk = 0;
WRITE_ONCE(i2c_imx->clk_rate, clk_get_rate(i2c_imx->clk));
ret = i2c_imx_set_clk(i2c_imx, READ_ONCE(i2c_imx->clk_rate));
if (ret)
dev_err(dev, "can't set I2C clock, ret=%d\n", ret);
}

return ret;
}
Expand Down