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Message-id: <412a0238-dd8e-6c74-46a7-876e112189f1@samsung.com>
Date: Thu, 05 Jan 2017 07:55:29 +0100
From: Andrzej Hajda <a.hajda@...sung.com>
To: Rob Herring <robh@...nel.org>,
Hoegeun Kwon <hoegeun.kwon@...sung.com>
Cc: thierry.reding@...il.com, airlied@...ux.ie, kgene@...nel.org,
krzk@...nel.org, inki.dae@...sung.com,
dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
devicetree@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
cw00.choi@...sung.com, jh80.chung@...sung.com,
Donghwa Lee <dh09.lee@...sung.com>,
Hyungwon Hwang <human.hwang@...sung.com>
Subject: Re: [PATCH v5 2/3] drm/panel: Add support for S6E3HA2 panel driver on
TM2 board
On 04.01.2017 15:44, Rob Herring wrote:
> On Wed, Jan 04, 2017 at 05:15:10PM +0900, Hoegeun Kwon wrote:
>> This patch add support for MIPI-DSI based S6E3HA2 AMOLED panel
>> driver. This panel has 1440x2560 resolution in 5.7-inch physical
>> panel in the TM2 device.
>>
>> Signed-off-by: Donghwa Lee <dh09.lee@...sung.com>
>> Signed-off-by: Hyungwon Hwang <human.hwang@...sung.com>
>> Signed-off-by: Hoegeun Kwon <hoegeun.kwon@...sung.com>
>> ---
>> .../bindings/display/panel/samsung,s6e3ha2.txt | 40 ++
>> drivers/gpu/drm/panel/Kconfig | 6 +
>> drivers/gpu/drm/panel/Makefile | 1 +
>> drivers/gpu/drm/panel/panel-samsung-s6e3ha2.c | 741 +++++++++++++++++++++
>> 4 files changed, 788 insertions(+)
>> create mode 100644 Documentation/devicetree/bindings/display/panel/samsung,s6e3ha2.txt
>> create mode 100644 drivers/gpu/drm/panel/panel-samsung-s6e3ha2.c
>>
>> diff --git a/Documentation/devicetree/bindings/display/panel/samsung,s6e3ha2.txt b/Documentation/devicetree/bindings/display/panel/samsung,s6e3ha2.txt
>> new file mode 100644
>> index 0000000..6879f51
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/display/panel/samsung,s6e3ha2.txt
>> @@ -0,0 +1,40 @@
>> +Samsung S6E3HA2 5.7" 1440x2560 AMOLED panel
>> +
>> +Required properties:
>> + - compatible: "samsung,s6e3ha2"
>> + - reg: the virtual channel number of a DSI peripheral
>> + - vdd3-supply: I/O voltage supply
>> + - vci-supply: voltage supply for analog circuits
>> + - reset-gpios: a GPIO spec for the reset pin (active low)
>> + - enable-gpios: a GPIO spec for the panel enable pin (active high)
>> + - te-gpios: a GPIO spec for the tearing effect synchronization signal
>> + gpio pin (active high)
>> +
>> +The device node can contain one 'port' child node with one child
>> +'endpoint' node, according to the bindings defined in [1]. This
>> +node should describe panel's video bus.
>> +
>> +[1]: Documentation/devicetree/bindings/media/video-interfaces.txt
>> +
>> +Example:
>> +
>> +&dsi {
>> + ...
>> +
>> + panel@0 {
>> + compatible = "samsung,s6e3ha2";
>> + reg = <0>;
>> + vdd3-supply = <&ldo27_reg>;
>> + vci-supply = <&ldo28_reg>;
>> + reset-gpios = <&gpg0 0 GPIO_ACTIVE_LOW>;
>> + enable-gpios = <&gpf1 5 GPIO_ACTIVE_HIGH>;
>> + te-gpios = <&gpf1 3 GPIO_ACTIVE_HIGH>;
>> +
>> + port {
>> + panel_in: endpoint {
>> + remote-endpoint = <&dsi_out>;
> As I said previously, it makes no sense to have a graph to dsi_out it is
> simply the parent node.
The problem is that exynos_dsi requires presence of endpoint node, when
it was written the policy was that graphs must be always present.
DSI reads from this node samsung,burst-clock-frequency and
samsung,esc-clock-frequency. For example in exynos4412-trats2.dts:
> dsi_0: dsi@...80000 {
> ...
> ports {
> #address-cells = <1>;
> #size-cells = <0>;
>
> port@1 {
> reg = <1>;
>
> dsi_out: endpoint {
> remote-endpoint = <&dsi_in>;
> samsung,burst-clock-frequency
> = <500000000>;
> samsung,esc-clock-frequency =
> <20000000>;
> };
> };
> };
>
> panel@0 {
> ...
> port {
> dsi_in: endpoint {
> remote-endpoint = <&dsi_out>;
> };
> };
> };
> };
However, DSI driver does not use remote-endpoint property, it is here
only to fulfill of_graph policy.
So if something like below is acceptable, we can get rid of port node in
panel:
> dsi_0: dsi@...80000 {
> ...
> ports {
> #address-cells = <1>;
> #size-cells = <0>;
>
> port@1 {
> reg = <1>;
>
> dsi_out: endpoint {
> samsung,burst-clock-frequency
> = <500000000>;
> samsung,esc-clock-frequency =
> <20000000>;
> };
> };
> };
>
> panel@0 {
> ...
> };
> };
What do you think?
Other solution is to move problematic properties somewhere else, but
this require change of bindings.
Anyway I would be glad to remove port nodes in other samsung panels:
s6e8aa0, ld9040.
Regards
Andrzej
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