[PATCH V11 2/2] media: i2c: ov02a10: Add OV02A10 image sensor driver
tfiga at chromium.org
Tue Jun 30 10:40:12 EDT 2020
On Tue, Jun 30, 2020 at 4:37 PM Andy Shevchenko
<andriy.shevchenko at linux.intel.com> wrote:
> On Tue, Jun 30, 2020 at 04:21:31PM +0200, Tomasz Figa wrote:
> > On Tue, Jun 30, 2020 at 4:19 PM Tomasz Figa <tfiga at chromium.org> wrote:
> > > On Tue, Jun 30, 2020 at 11:54 AM Sakari Ailus
> > > <sakari.ailus at linux.intel.com> wrote:
> > > > > + ov02a10->rst_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
> > > >
> > > >
> > > > Shouldn't this be GPIOD_OUT_HIGH? That's the state it'll be after powering
> > > > the sensor off the first time. Alternatively make reset signal high in
> > > > runtime suspend callback.
> > >
> > > We might want to keep the signals low when the regulators are powered
> > > down, to reduce the leakage.
> > Ah, I actually recall that the reset pin was physically active low, so
> > we would indeed better keep it at HIGH. Sorry for the noise.
> Here HIGH means "asserted", so in the code above it's LOW, means "deasserted",
> i.o.w. non-reset state. I dunno what is better, it depends to the firmware /
> driver expectations of the device configuration (from the power point of view,
> HIGH makes sense here, and not LOW, i.o.w. asserted reset line).
> And nice of the logical state that it doesn't depend to the active low / high
> (the latter just transparent to the user).
Yeah, after reading through the GPIO subsystem documentation and
discussing with a bunch of people on how to interpret it, we concluded
that the driver needs to deal only with the logical state of the
Actually, I later realized that the problem of leakage should likely
be solved by pinctrl suspend settings, based on given hardware
conditions, rather than the driver explicitly.
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