On 15 May 2017 at 18:16, Rob Herring [off-list ref] wrote:

On Mon, May 15, 2017 at 6:08 AM, Ulf Hansson [off-list ref] wrote:

quoted

On 12 May 2017 at 22:03, Rob Herring [off-list ref] wrote:

quoted

On Mon, May 08, 2017 at 06:21:10PM +0200, Ulf Hansson wrote:

quoted

During power off, after the GPIO pin has been asserted, some devices like
the Wifi chip from TI, Wl18xx, needs a delay before the host continues with
clock gating and turning off regulators as to follow a graceful shutdown
sequence.

Therefore invent an optional power-off-delay-us DT binding for
mmc-pwrseq-simple, to allow us to support this constraint.

Do you really need this to be programmable per device. A delay is not
going to hurt devices that don't need it.

Well, that depends on what "hurt" means. The device would still be
properly shut down, only that it would take unnecessary longer to do
so.

I think the problem here, is that this delay may also affect system
suspend/resume time of the device, if the device powers off/on in this
sequence.

I was assuming that given you changed the units the time was small
enough to not be significant.

That's right. We are in the range of < 50us, which is suitable for the
Wl18xx chip.

However, the problem occurs when some other device needs a longer
delay and then we may reach a threshold that isn't acceptable.

To me it's better to allow it to be described in DT - then only
influencing those devices that really needs it.

quoted

quoted

Sorry, but this is exactly what I don't like about "simple" bindings:
adding one property at a time.

I understand you opinion, which in the end is a matter of taste/flavor.

It's more than that. The problem is you would end up with a different
binding if everything is defined up front versus reviewing one
addition at a time.

To give a trivial example here, now we have power on and off times in
different units and if I was reviewing them together I would say make
them both usec. That example is mostly taste, but different units also
makes it more error prone for the dts writer.

Okay, I see your a point.

quoted

However, for me this just follows the existing approach - and suddenly
say no to this, doesn't really seems right either.

I never said no.

Alright. Is that a yes then? :-)

If not, what do you prefer me to do?

Kind regards
Uffe