Re: [PATCH v2 2/4] dt-bindings: gnss: add mediatek binding

From: Loys Ollivier
Date: Mon Jan 28 2019 - 10:47:05 EST

On Fri 25 Jan 2019 at 09:07, Johan Hovold wrote:

On Thu, Jan 17, 2019 at 05:54:32PM +0100, Loys Ollivier wrote:
Add binding for Mediatek-based GNSS receivers.

Signed-off-by: Loys Ollivier <lollivier@xxxxxxxxxxxx>

Renamed bindings from Globaltop/gtop to Mediatek/mtk.
Moved current-speed as an optional propertie.
Removed the status line in the example.
Added "mediatek,mt3339" compatible.

.../devicetree/bindings/gnss/mediatek.txt | 39 ++++++++++++++++++++++
1 file changed, 39 insertions(+)
create mode 100644 Documentation/devicetree/bindings/gnss/mediatek.txt

diff --git a/Documentation/devicetree/bindings/gnss/mediatek.txt b/Documentation/devicetree/bindings/gnss/mediatek.txt
new file mode 100644
index 000000000000..fd984b4a9a6d
--- /dev/null
+++ b/Documentation/devicetree/bindings/gnss/mediatek.txt
@@ -0,0 +1,39 @@
+Mediatek-based GNSS Receiver DT binding
+Mediatek chipsets are used in GNSS-receiver modules produced by several
+vendors and can use UART, SPI or I2C interfaces.
+Please see Documentation/devicetree/bindings/gnss/gnss.txt for generic
+Required properties:
+- compatible : Must be one of
+ "globaltop,pa6h"
+ "mediatek,mt3339"

I'm not sure it makes sense to add the GPS chip itself as it cannot be
used stand-alone AFAIU, and either not way would require a lot more
resources to be defined than what you add to this binding.

OK, I find it a bit confusing to have Mediatek bindings but no
compatible Mediatek SoCs.
But it is true that it can't be used stand-alone. I will remove this
reference and also remove it from the mtk.c driver code from this patch

+- vcc-supply : Main voltage regulator (pin name: 3V3_IN, VCC, VDD)

The pin names in parenthesis were copied from the sirf-star binding and
were used to capture the various names given to this supply by different
vendors. Please drop as it doesn't apply here.

+Required properties (I2C):
+- reg : I2C slave address
+Required properties (SPI):
+- reg : SPI chip select address

While the mt3339 appears to support these interfaces, the globaltop one
does not.

Have you looked around for a small sample of mt3339-based receivers, to
see whether anyone actually provides these?

Again I'm confused by the fact that it is the Mediatek bindings.
Hence why I have added it and why it was not present in the v1 that was
only for Globaltop.
I find it odd mentionning the chipset but not all its interfaces.
I will remove these sections and only list supported interfaces (i.e.
UART). Other interfaces can be added afterward if one finds a board that
provides them.

+Optional properties:
+- timepulse-gpios : Time pulse GPIO
+- v-bckp-supply : Backup voltage regulator
+- current-speed : Default UART baud rate

Looks like you forgot the optional NRESET input and 3D-FIX output (even
if the latter might be of limited use).

Thanks I will clean this section.

+serial@1234 {
+ compatible = "ns16550a";
+ gnss {
+ compatible = "globaltop,pa6h";
+ vcc-supply = <&vcc_3v3>;
+ };