Am 2021-10-12 08:17, schrieb Alexander Stein:
This property is for optimizing output voltage impedance and is
specific to each board. It overwrites the default set by the flash
device. Various flash devices support different impedances.
Signed-off-by: Alexander Stein <alexander.stein@xxxxxxxxxxxxxxx>
---
Changes in v2:
* Updated the property description and the commit message accordingly
Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml
b/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml
index ed590d7c6e37..4c3c506a8853 100644
--- a/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml
+++ b/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml
@@ -72,6 +72,14 @@ properties:
be used on such systems, to denote the absence of a reliable
reset
mechanism.
+ output-driver-strength:
+ $ref: /schemas/types.yaml#/definitions/uint32
+ description:
+ Output driver strength in ohms which optimizes the impedance at
Vcc/2
+ output voltage. This property overwrites the default set by the
flash
+ device. This is board specific and should be determined by the
+ manufacturer. Various flash devices support different
impedances.
Mh, this seems to be very tailored to this flash chip. Eg. the "Vcc/2",
is
this something specific to this flash or is this some kind of common
usage?
For example, Winbond flashes specifies the output driver strength in
percent.
Settings are 25%, 50%, 75%, 100% there.
I'd have to ask a hardware guy, if one could convert between these two
representations of the driver strength.
Rob, do you know how is this case ususally handled? Can there be
different
properties, like:
output-driver-strength-ohms
output-driver-strength-percent
or similar.
-michael
