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i2c: lpi2c: Avoid calling clk_get_rate during transfer

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Instead of repeatedly calling clk_get_rate for each transfer, lock
the clock rate and cache the value.
A deadlock has been observed while adding tlv320aic32x4 audio codec to
the system. When this clock provider adds its clock, the clk mutex is
locked already, it needs to access i2c, which in return needs the mutex
for clk_get_rate as well.

Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Andi Shyti <andi.shyti@kernel.org>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
This commit is contained in:
Alexander Stein 2024-04-22 13:36:29 +02:00 committed by Andi Shyti
parent 355b1513b1
commit 4268254a39
1 changed files with 16 additions and 3 deletions
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19
drivers/i2c/busses/i2c-imx-lpi2c.c
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@ -99,6 +99,7 @@ struct lpi2c_imx_struct {
__u8 *rx_buf;
__u8 *tx_buf;
struct completion complete;
unsigned long rate_per;
unsigned int msglen;
unsigned int delivered;
unsigned int block_data;
@ -212,9 +213,7 @@ static int lpi2c_imx_config(struct lpi2c_imx_struct *lpi2c_imx)
lpi2c_imx_set_mode(lpi2c_imx);
clk_rate = clk_get_rate(lpi2c_imx->clks[0].clk);
if (!clk_rate)
return -EINVAL;
clk_rate = lpi2c_imx->rate_per;
if (lpi2c_imx->mode == HS || lpi2c_imx->mode == ULTRA_FAST)
filt = 0;
@ -611,6 +610,20 @@ static int lpi2c_imx_probe(struct platform_device *pdev)
if (ret)
return ret;
/*
* Lock the parent clock rate to avoid getting parent clock upon
* each transfer
*/
ret = devm_clk_rate_exclusive_get(&pdev->dev, lpi2c_imx->clks[0].clk);
if (ret)
return dev_err_probe(&pdev->dev, ret,
"can't lock I2C peripheral clock rate\n");
lpi2c_imx->rate_per = clk_get_rate(lpi2c_imx->clks[0].clk);
if (!lpi2c_imx->rate_per)
return dev_err_probe(&pdev->dev, -EINVAL,
"can't get I2C peripheral clock rate\n");
pm_runtime_set_autosuspend_delay(&pdev->dev, I2C_PM_TIMEOUT);
pm_runtime_use_autosuspend(&pdev->dev);
pm_runtime_get_noresume(&pdev->dev);