From 4268254a39484fc11ba991ae148bacbe75d9cc0a Mon Sep 17 00:00:00 2001 From: Alexander Stein Date: Mon, 22 Apr 2024 13:36:29 +0200 Subject: [PATCH] i2c: lpi2c: Avoid calling clk_get_rate during transfer MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Reviewed-by: Uwe Kleine-König Reviewed-by: Andi Shyti Signed-off-by: Andi Shyti --- drivers/i2c/busses/i2c-imx-lpi2c.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/drivers/i2c/busses/i2c-imx-lpi2c.c b/drivers/i2c/busses/i2c-imx-lpi2c.c index 6d72e4e126dd..36e8f6196a87 100644 --- a/drivers/i2c/busses/i2c-imx-lpi2c.c +++ b/drivers/i2c/busses/i2c-imx-lpi2c.c @@ -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);