Thread (9 messages) 9 messages, 2 authors, 2016-08-24

Re: [RESEND] [PATCH v2 2/4] dt-bindings: Add jdi lt070me05000 panel bindings

From: Vinay Simha <hidden>
Date: 2016-08-24 12:24:04
Also in: dri-devel, lkml

if we do not set the polarity to 8mA, panel will have gibberish display.
(information to set 8mA is available only in
nexus7-msm-flo-3.4-lollipop-release_dsi kernel nx7 release)

i will add this
reset-gpios = <&tlmm_pinmux 54 GPIO_ACTIVE_LOW>;

On Wed, Aug 24, 2016 at 5:26 PM, Thierry Reding
[off-list ref] wrote:
On Sun, Jul 31, 2016 at 08:45:21PM +0530, Vinay Simha BN wrote:
[...]
quoted
diff --git a/Documentation/devicetree/bindings/display/panel/jdi,lt070me05000.txt b/Documentation/devicetree/bindings/display/panel/jdi,lt070me05000.txt
[...]
quoted
+- reset-gpios: phandle of gpio for reset line
+  This should be 8mA, gpio can be configured using mux, pinctrl, pinctrl-names
+  XRES, Reset, Low active
+- enable-gpios: phandle of gpio for enable line
+  LED_EN, LED backlight enable, High active
This is a little confusing. Shouldn't we rather completely omit any
mention of the polarity of these and let the board design handle this?

If the reset is low active, then I'd expect that to be reflected in the
GPIO specifier of the reset-gpios property, like so:

        panel@0 {
                ...
                reset-gpios = <&tlmm_pinmux 54 GPIO_ACTIVE_LOW>;
                ...
        };

With that a driver can simply deal with a high active reset, which it
currently doesn't. The problem with the current description is that it
is unclear who's to deal with the polarity. In order for this to work
properly with the current driver you'll have to specify the GPIO as
GPIO_ACTIVE_HIGH, which is not what the binding says it should be.

Thierry


-- 
regards,
vinaysimha
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