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Message-ID: <33dc7f60-4364-4d7a-a66b-4bd881b41675@collabora.com>
Date: Tue, 24 Sep 2024 10:39:03 +0200
From: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
To: "zoie.lin" <zoie.lin@...iatek.com>, Qii Wang <qii.wang@...iatek.com>,
Andi Shyti <andi.shyti@...nel.org>, Matthias Brugger <matthias.bgg@...il.com>
Cc: Project_Global_Chrome_Upstream_Group@...iatek.com,
linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, linux-mediatek@...ts.infradead.org
Subject: Re: [v1,1/1] i2c: mediatek: add runtime PM operations and bus
regulator control
Il 20/09/24 16:36, zoie.lin ha scritto:
> This commit introduces support for runtime PM operations in
> the I2C driver, enabling runtime suspend and resume functionality.
>
> Although in the most platforms, the bus power of i2c are always
> on, some platforms disable the i2c bus power in order to meet
> low power request.
>
> This implementation includes bus regulator control to facilitate
> proper handling of the bus power based on platform requirements.
>
> Signed-off-by: zoie.lin <zoie.lin@...iatek.com>
Hello Zoie,
Your name does not technically have any "." inside, so please fix it
so that it reads `Zoie Lin <zoie.lin@...iatek.com>`.
Moreover, this implementation can be improved. Check below:
You missed pm_runtime_status_suspended() checks in suspend/resume callbacks
and, if the bus wasn't already runtime suspended when reaching suspend(), that
will not get the bus regulators powered off when suspending; analogously, if
the device was runtime suspended, the regulators and clocks will stay on when
resuming from system sleep until first usage.
So add the checks:
static int mtk_i2c_suspend_noirq(struct device *dev)
{
struct mtk_i2c *i2c = dev_get_drvdata(dev);
i2c_mark_adapter_suspended(&i2c->adap);
if (!pm_runtime_status_suspended(dev))
mtk_i2c_runtime_suspend(dev);
clk_bulk_unprepare(I2C_MT65XX_CLK_MAX, i2c->clocks);
return 0;
}
static int mtk_i2c_resume_noirq(struct device *dev)
{
int ret;
struct mtk_i2c *i2c = dev_get_drvdata(dev);
ret = clk_bulk_prepare_enable(I2C_MT65XX_CLK_MAX, i2c->clocks);
if (ret) {
dev_err(dev, "clock enable failed!\n");
return ret;
}
mtk_i2c_init_hw(i2c);
if (pm_runtime_status_suspended(dev))
ret = mtk_i2c_runtime_suspend(dev);
i2c_mark_adapter_resumed(&i2c->adap);
return 0;
}
> ---
> drivers/i2c/busses/i2c-mt65xx.c | 72 ++++++++++++++++++++++++++++-----
> 1 file changed, 61 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-mt65xx.c b/drivers/i2c/busses/i2c-mt65xx.c
> index e0ba653dec2d..aae0189ba210 100644
> --- a/drivers/i2c/busses/i2c-mt65xx.c
> +++ b/drivers/i2c/busses/i2c-mt65xx.c
> @@ -21,6 +21,7 @@
> #include <linux/module.h>
> #include <linux/of.h>
> #include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
> #include <linux/scatterlist.h>
> #include <linux/sched.h>
> #include <linux/slab.h>
> @@ -1245,8 +1246,8 @@ static int mtk_i2c_transfer(struct i2c_adapter *adap,
> int left_num = num;
> struct mtk_i2c *i2c = i2c_get_adapdata(adap);
>
> - ret = clk_bulk_enable(I2C_MT65XX_CLK_MAX, i2c->clocks);
> - if (ret)
> + ret = pm_runtime_get_sync(i2c->dev);
ret = pm_runtime_resume_and_get(i2c->dev);
> + if (ret < 0)
> return ret;
>
> i2c->auto_restart = i2c->dev_comp->auto_restart;
> @@ -1299,7 +1300,9 @@ static int mtk_i2c_transfer(struct i2c_adapter *adap,
> ret = num;
>
> err_exit:
> - clk_bulk_disable(I2C_MT65XX_CLK_MAX, i2c->clocks);
> + pm_runtime_mark_last_busy(i2c->dev);
> + pm_runtime_put_autosuspend(i2c->dev);
> +
> return ret;
> }
>
> @@ -1370,6 +1373,41 @@ static int mtk_i2c_parse_dt(struct device_node *np, struct mtk_i2c *i2c)
> return 0;
> }
>
> +static int mtk_i2c_runtime_suspend(struct device *dev)
> +{
> + struct mtk_i2c *i2c = dev_get_drvdata(dev);
> +
> + clk_bulk_disable(I2C_MT65XX_CLK_MAX, i2c->clocks);
> + if (i2c->adap.bus_regulator)
> + regulator_disable(i2c->adap.bus_regulator);
> +
> + return 0;
> +}
> +
> +static int mtk_i2c_runtime_resume(struct device *dev)
> +{
> + int ret = 0;
> + struct mtk_i2c *i2c = dev_get_drvdata(dev);
struct mtk_i2c *i2c = dev_get_drvdata(dev);
int ret;
> +
> + if (i2c->adap.bus_regulator) {
> + ret = regulator_enable(i2c->adap.bus_regulator);
> + if (ret < 0) {
`ret` can't be > 0. `if (ret) {` is enough.
> + dev_err(dev, "enable regulator failed!\n");
> + return ret;
> + }
> + }
> +
> + ret = clk_bulk_enable(I2C_MT65XX_CLK_MAX, i2c->clocks);
> + if (ret < 0) {
if (ret) {
> + dev_err(dev, "clock enable failed!\n");
This print is unnecessary.
> + if (i2c->adap.bus_regulator)
> + regulator_disable(i2c->adap.bus_regulator);
> + return ret;
> + }
> +
> + return ret;
return 0;
> +}
> +
> static int mtk_i2c_probe(struct platform_device *pdev)
> {
> int ret = 0;
> @@ -1472,13 +1510,19 @@ static int mtk_i2c_probe(struct platform_device *pdev)
> }
> }
>
> - ret = clk_bulk_prepare_enable(I2C_MT65XX_CLK_MAX, i2c->clocks);
> + ret = clk_bulk_prepare(I2C_MT65XX_CLK_MAX, i2c->clocks);
> if (ret) {
> - dev_err(&pdev->dev, "clock enable failed!\n");
> + dev_err(&pdev->dev, "clk_bulk_prepare failed\n");
This print is anyway redundant, as clk_bulk_prepare() already prints upon failures,
so you can as well simply remove it instead of changing it.
> return ret;
> }
> +
> + platform_set_drvdata(pdev, i2c);
> +
> + ret = mtk_i2c_runtime_resume(i2c->dev);
> + if (ret < 0)
> + goto err_clk_bulk_unprepare;
> mtk_i2c_init_hw(i2c);
> - clk_bulk_disable(I2C_MT65XX_CLK_MAX, i2c->clocks);
> + mtk_i2c_runtime_suspend(i2c->dev);
>
> ret = devm_request_irq(&pdev->dev, irq, mtk_i2c_irq,
> IRQF_NO_SUSPEND | IRQF_TRIGGER_NONE,
> @@ -1486,19 +1530,22 @@ static int mtk_i2c_probe(struct platform_device *pdev)
> if (ret < 0) {
> dev_err(&pdev->dev,
> "Request I2C IRQ %d fail\n", irq);
> - goto err_bulk_unprepare;
> + goto err_clk_bulk_unprepare;
> }
> + pm_runtime_set_autosuspend_delay(&pdev->dev, 1000);
One full second as autosuspend delay? Can this be shortened to 500? 250?
How was the one second wait chosen?
How much time does mtk_i2c_runtime_resume() take to resume the bus?
> + pm_runtime_use_autosuspend(&pdev->dev);
> + pm_runtime_enable(&pdev->dev);
>
> i2c_set_adapdata(&i2c->adap, i2c);
> ret = i2c_add_adapter(&i2c->adap);
> if (ret)
> - goto err_bulk_unprepare;
> -
> - platform_set_drvdata(pdev, i2c);
> + goto err_pm_runtime_disable;
>
> return 0;
>
> -err_bulk_unprepare:
> +err_pm_runtime_disable:
> + pm_runtime_disable(&pdev->dev);
> +err_clk_bulk_unprepare:
> clk_bulk_unprepare(I2C_MT65XX_CLK_MAX, i2c->clocks);
>
> return ret;
> @@ -1510,6 +1557,7 @@ static void mtk_i2c_remove(struct platform_device *pdev)
>
> i2c_del_adapter(&i2c->adap);
>
> + pm_runtime_disable(&pdev->dev);
pm_runtime_set_suspended(&pdev->dev);
> clk_bulk_unprepare(I2C_MT65XX_CLK_MAX, i2c->clocks);
> }
>
Regards,
Angelo
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