On Mon, Sep 23, 2019 at 12:05:57PM -0500, Benoit Parrot wrote: > Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx> wrote on Mon [2019-Sep-23 09:17:32 +0300]: > > Hi Benoit, > > > > On Fri, Sep 20, 2019 at 11:55:29AM -0500, Benoit Parrot wrote: > > ... > > > > > @@ -1400,6 +1440,18 @@ static int ov2659_probe(struct i2c_client *client) > > > > > ov2659->xvclk_frequency > 27000000) > > > > > return -EINVAL; > > > > > > > > > > + /* Optional gpio don't fail if not present */ > > > > > + ov2659->pwdn_gpio = devm_gpiod_get_optional(&client->dev, "powerdown", > > > > > + GPIOD_OUT_LOW); > > > > > + if (IS_ERR(ov2659->pwdn_gpio)) > > > > > + return PTR_ERR(ov2659->pwdn_gpio); > > > > > + > > > > > + /* Optional gpio don't fail if not present */ > > > > > + ov2659->resetb_gpio = devm_gpiod_get_optional(&client->dev, "reset", > > > > > + GPIOD_OUT_HIGH); > > > > > + if (IS_ERR(ov2659->resetb_gpio)) > > > > > + return PTR_ERR(ov2659->resetb_gpio); > > > > > + > > > > > v4l2_ctrl_handler_init(&ov2659->ctrls, 2); > > > > > ov2659->link_frequency = > > > > > v4l2_ctrl_new_std(&ov2659->ctrls, &ov2659_ctrl_ops, > > > > > @@ -1445,6 +1497,9 @@ static int ov2659_probe(struct i2c_client *client) > > > > > ov2659->frame_size = &ov2659_framesizes[2]; > > > > > ov2659->format_ctrl_regs = ov2659_formats[0].format_ctrl_regs; > > > > > > > > > > + pm_runtime_enable(&client->dev); > > > > > + pm_runtime_get_sync(&client->dev); > > > > > > > > This makes the driver depend on runtime PM. > > > > > > Obviously. > > > Why? Is that bad? > > > > Well, if it is, then it should be listed in driver's dependencies in > > Kconfig. > > And I see that most camera driver using pm_runtime calls don't mark it as a > dependency in their own Kconfig. There is actually only one that does. Drivers should also work without runtime PM even if they can use it. > > > > > > > > > > > > > > See e.g. the smiapp driver for an example how to make it work without. It > > > > wasn't trivial. :I You won't need autosuspend. > > > > > > I took a look at that driver, but I don't get your reference to being able > > > to work without runtime pm! > > > > The driver didn't need runtime PM, so it'd be nice to continue work > > without. > > Ok. > > > > > What smiapp does is that it powers the sensor on first *without* runtime > > PM, and then proceeds to set up runtime PM if it's available. The sensor > > will only be powered off when the device is unbound with runtime PM > > disabled. > > In that case in your original reply you suggested that I move the content > of ov2659_set_power() into the pm_runtime callback, but based on this > comments then I should keep ov2659_set_power() as is as I would need to > use it for this specific purpose. No need to; you can call the same function elsewhere in the driver (just like the smiapp driver does). > > > > > Regarding the smiapp driver, you can replace pm_runtime_get_noresume() and > > all the autoidle lines with pm_runtime_idle() call after > > pm_runtime_enable() in the ov2659 driver. > > Ok, I'll study this mechanics a little more, as this is not immediately > clear. > > Benoit > > > > > > That driver looks pretty similar to ov7740.c which I used as a reference > > > for this. > > > > I guess in practice many sensor drivers don't work without it on DT-based > > systems I'm afraid. :-( They should be fixed. > > > > -- > > Kind regards, > > > > Sakari Ailus > > sakari.ailus@xxxxxxxxxxxxxxx -- Sakari Ailus sakari.ailus@xxxxxxxxxxxxxxx
