On 25/11/2022 10:47, Linus Walleij wrote:
On Thu, Nov 24, 2022 at 2:24 PM Neil Armstrong
<neil.armstrong@xxxxxxxxxx> wrote:
On 24/11/2022 14:11, Linus Walleij wrote:
On Wed, Nov 23, 2022 at 4:20 PM Abel Vesa <abel.vesa@xxxxxxxxxx> wrote:
From: Neil Armstrong <neil.armstrong@xxxxxxxxxx>
Document the new i2c_pull property introduced for SM8550 setting
an I2C specific pull mode on I2C able pins.
Signed-off-by: Neil Armstrong <neil.armstrong@xxxxxxxxxx>
Signed-off-by: Abel Vesa <abel.vesa@xxxxxxxxxx>
(...)
+ qcom,i2c-pull:
+ type: boolean
+ description: enable bias pull feature designed for I2C on pin
But what is this?
I2C buses are usually just plain old bias-high-impedance, high-z
or open drain, wire-or or whatever you want to call it.
But now there is some special i2c mode, huh?
The description is pretty much "it is what it is"... can we have
some explanation about what this means electrically speaking
and why you cannot use bias-high-impedance?
I'll try to get some more info, but so far I only found what I wrote in the bindings.
Björn: can you see if you can get some clarity about the i2c
bias thing?
As I understood, it enables an "I2C resistor" on the pin, removing the need
of an external pull-up resistor on the line.
I assume the classical pull-up bias is not strong enough to replace an actual
resistor on the PCB.
Neil
Yours,
Linus Walleij
