On 21/11/2017 23:21, Sebastian Reichel wrote:
Hi,
On Tue, Nov 21, 2017 at 10:46:29PM +0800, Phil Reid wrote:
G'day Sebastian,
On 21/11/2017 21:34, Sebastian Reichel wrote:
Hi,
On Tue, Nov 21, 2017 at 04:21:30PM +0800, Phil Reid wrote:
The irq polarity is already encoded in the irq config. Use that to
determine the polarity for the mcp32s08 irq output instead of the
custom microchip,irq-active-high property.
Signed-off-by: Phil Reid <preid@xxxxxxxxxxxxxxxxx>
---
I don't like, that we use the flags for configuring the host
interrupt input and the mcp23xxx interrupt output. Usually
when the interrupt line has an inverter on it, board DTS files
just toggle the interrupts polarity. This will not work with
this patch applied. We would need to explicitly add an inverter
in the interrupt line, which is completely different to how its
implemented everywhere else (I know at least some Tegra devices
have implicit inverters on interrupt lines).
In case this is really wanted, this patch and the first patch
should be merged to avoid temporarily exposing the splitted
logic.
Thanks for looking at the series.
Yes I understand where your coming from. And that's exactly what I
was trying to do in v2. I have 2 of these devices with open drain output
that is feed to an inverter. So active low output from devices and irq
consumer is active high input.
However Linux wasn't a fan of the property and wanted it gone.
I guess s/Linux/Linus Walleij/?
oops, yes.
He suggested we need a "inverter" device to allow for that in the
device tree. I haven't got my head around how to do that thou.
Just to be on the same term, we are talking about these two variants:
--------------------------------------------
gpio: host-gpio {
random-properties;
}
inv: line-inverter {
/*
* configure the gpio controller input to be active low
* and the inverter interrupt output to be active low
*/
interrupts = <&gpio ACTIVE_LOW>;
};
mcp23xxx {
random-properties;
/*
* configure the chip interrupt output to be active high
* and the inverter interrupt input to be active high
*/
interrupts = <&inv ACTIVE_HIGH>;
}
--------------------------------------------
versus
--------------------------------------------
gpio: host-gpio {
random-properties;
}
mcp23xxx {
random-properties;
/* configure host interrupt input pin to be active low */
interrupts = <&gpio ACTIVE_LOW>;
/* configure chip interrupt output pin to be active high */
microchip,irq-active-high;
}
--------------------------------------------
I think this is something, that Rob should comment on. Obviously at
least in the mainline kernel nobody implemented the first solution
(since there is no fitting interrupt-invert driver), but there are
a few instances of the second variant. On the other hand the first
solution describes the hardware more detailed.
Yes that was my understanding of the options, with option 1 being favoured.
Nice summary of the options.
And if someone is relying on that implicit behaviour are we allowed
to break things? Probably ok with this one as it's currently not possible
due to code patch 1 removes.
If we need to model the invert to get the patches accepted I look into that.
I don't actually need it for my system as I can set open-drain with overrides
the active-high control on this device, while have active high irq consumer.
:)
IMHO the explicit line-inverter is a bit over-engineered and
implicit line-inverter is enough, but I'm fine with both solutions.
I think the DT binding maintainers should comment on this though,
since it's pretty much a core decision about interrupt specifiers.
Thanks again, I'll await further feedback on the preferred direction.>
-- Sebastian
drivers/pinctrl/pinctrl-mcp23s08.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/drivers/pinctrl/pinctrl-mcp23s08.c b/drivers/pinctrl/pinctrl-mcp23s08.c
index 8ff9b77..6b3f810 100644
--- a/drivers/pinctrl/pinctrl-mcp23s08.c
+++ b/drivers/pinctrl/pinctrl-mcp23s08.c
@@ -773,6 +773,7 @@ static int mcp23s08_probe_one(struct mcp23s08 *mcp, struct device *dev,
bool mirror = false;
bool irq_active_high = false;
bool open_drain = false;
+ u32 irq_trig;
mutex_init(&mcp->lock);
@@ -863,9 +864,13 @@ static int mcp23s08_probe_one(struct mcp23s08 *mcp, struct device *dev,
mcp->irq_controller =
device_property_read_bool(dev, "interrupt-controller");
if (mcp->irq && mcp->irq_controller) {
- irq_active_high =
- device_property_read_bool(dev,
- "microchip,irq-active-high");
+ if (device_property_present(dev, "microchip,irq-active-high"))
+ dev_warn(dev,
+ "microchip,irq-active-high is deprecated\n");
+
+ irq_trig = irqd_get_trigger_type(irq_get_irq_data(mcp->irq));
+ if (irq_trig == IRQF_TRIGGER_HIGH)
+ irq_active_high = true;
mirror = device_property_read_bool(dev, "microchip,irq-mirror");
open_drain = device_property_read_bool(dev, "drive-open-drain");
--
1.8.3.1
--
Regards
Phil Reid
ElectroMagnetic Imaging Technology Pty Ltd
Development of Geophysical Instrumentation & Software
www.electromag.com.au
3 The Avenue, Midland WA 6056, AUSTRALIA
Ph: +61 8 9250 8100
Fax: +61 8 9250 7100
Email: preid@xxxxxxxxxxxxxxxxx
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