| Message ID | 20230402105518.2512541-1-u.kleine-koenig@pengutronix.de |
|---|---|
| State | New |
| Headers | show |
| Series | i2c: omap: Don't do pm_runtime_resume in .remove() | expand |
Hi, On Sun, 2 Apr 2023 12:55:18 +0200 Uwe Kleine-König <u.kleine-koenig@pengutronix.de> wrote: > One of the first things that the driver's pm_runtime_resume callback > does is to write zero to the OMAP_I2C_CON_REG register. > So there is no need to have the device resumed just to write to the > OMAP_I2C_CON_REG register and the call to pm_runtime_resume_and_get() > can be dropped. > > The intended side effect of this commit is to remove an error path of > the function resulting in the remove callback returning a mostly ignored > error code. This prepares changing the prototype of struct > platform_driver's remove callback to return void. > > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> As far as I have understand the code that runtime resume is needed for enabling clocks to access the device Regards, Andreas
Hi, * Uwe Kleine-König <u.kleine-koenig@pengutronix.de> [230403 05:48]: > So if there is some clk handling necessary before the register access, > I'm not aware where it's hidden. Is there some bus or omap specific code > that ensures clk handling? I think the missing part is that the runtime PM calls in the i2c driver cause the parent ti-sysc interconnect target module device to get enabled and clocked before accessing the i2c registers. Regards, Tony
> > So if there is some clk handling necessary before the register access, > > I'm not aware where it's hidden. Is there some bus or omap specific code > > that ensures clk handling? > > I think the missing part is that the runtime PM calls in the i2c driver > cause the parent ti-sysc interconnect target module device to get enabled > and clocked before accessing the i2c registers. So, this patch is not needed?
diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c index f9ae520aed22..a572f6d994ca 100644 --- a/drivers/i2c/busses/i2c-omap.c +++ b/drivers/i2c/busses/i2c-omap.c @@ -1522,16 +1522,12 @@ omap_i2c_probe(struct platform_device *pdev) static int omap_i2c_remove(struct platform_device *pdev) { struct omap_i2c_dev *omap = platform_get_drvdata(pdev); - int ret; i2c_del_adapter(&omap->adapter); - ret = pm_runtime_resume_and_get(&pdev->dev); - if (ret < 0) - return ret; omap_i2c_write_reg(omap, OMAP_I2C_CON_REG, 0); + pm_runtime_dont_use_autosuspend(&pdev->dev); - pm_runtime_put_sync(&pdev->dev); pm_runtime_disable(&pdev->dev); return 0; }
One of the first things that the driver's pm_runtime_resume callback does is to write zero to the OMAP_I2C_CON_REG register. So there is no need to have the device resumed just to write to the OMAP_I2C_CON_REG register and the call to pm_runtime_resume_and_get() can be dropped. The intended side effect of this commit is to remove an error path of the function resulting in the remove callback returning a mostly ignored error code. This prepares changing the prototype of struct platform_driver's remove callback to return void. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> --- Hello, I'm not completely sure that the reasing in the commit log is sound. There might at least theoretical side effects of the register write that are different if the device is fully resumed. Best regards Uwe drivers/i2c/busses/i2c-omap.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) base-commit: fe15c26ee26efa11741a7b632e9f23b01aca4cc6