Re: [PATCH 6/6] drm/msm/dsi: Parse DSI lanes via DT

[Rob Herring <robh@kernel.org>]

On Mon, Feb 15, 2016 at 06:30:59PM +0530, Archit Taneja wrote:
> The DSI driver is currently unaware of how the DSI clock and data pins
> are mapped to the logical lanes provided by the DSI controller.
> 
> Use the generic 'lanes' DT binding provided for DSI lanes (used for DSI
> in bindings/display/ti/ti,omap4-dss.txt) to get the desired mapping.
> 
> The MSM DSI controller is restricted in terms of what all mappings
> it can support. The lane polarity is fixed for all the lanes, the clock
> lanes are fixed, and the data lanes can be swapped among each other only
> for a few combinations. Apply these restrictions when we parse the DT
> data.
> 
> Cc: devicetree@vger.kernel.org
> Cc: Rob Herring <robh@kernel.org>
> Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
> 
> Signed-off-by: Archit Taneja <architt@codeaurora.org>
> ---
>  .../devicetree/bindings/display/msm/dsi.txt        |  26 +++-
>  drivers/gpu/drm/msm/dsi/dsi_host.c                 | 146 ++++++++++++++++++---
>  2 files changed, 149 insertions(+), 23 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/display/msm/dsi.txt b/Documentation/devicetree/bindings/display/msm/dsi.txt
> index e7423be..f0d8b6f 100644
> --- a/Documentation/devicetree/bindings/display/msm/dsi.txt
> +++ b/Documentation/devicetree/bindings/display/msm/dsi.txt
> @@ -44,9 +44,28 @@ Optional properties:
>  - pinctrl-names: the pin control state names; should contain "default"
>  - pinctrl-0: the default pinctrl state (active)
>  - pinctrl-n: the "sleep" pinctrl state
> -- port: DSI controller output port. This contains one endpoint subnode, with its
> -  remote-endpoint set to the phandle of the connected panel's endpoint.
> -  See Documentation/devicetree/bindings/graph.txt for device graph info.
> +- port: DSI controller output port, containing one endpoint subnode.
> +
> +  DSI Endpoint properties:
> +  - remote-endpoint: set to phandle of the connected panel's endpoint.
> +    See Documentation/devicetree/bindings/graph.txt for device graph info.
> +  - lanes: list of pin numbers for the DSI lanes: CLKp, CLKn, DATA0p, DATA0n,
> +    DATA1p, DATA1n, ...
> +    This provides a physical to logical mapping of the DSI lanes. The CLKp and
> +    CLKn pins have to be mapped to pins 0 and 1. For data lanes, there are only

Then why describe the clk pins?

> +    a limited number of physical to logical mappings possible:
> +
> +     "0123": Logic 0->Phys 0; Logic 1->Phys 1; Logic 2->Phys 2; Logic 3->Phys 3;
> +     "3012": Logic 3->Phys 0; Logic 0->Phys 1; Logic 1->Phys 2; Logic 2->Phys 3;
> +     "2301": Logic 2->Phys 0; Logic 3->Phys 1; Logic 0->Phys 2; Logic 1->Phys 3;
> +     "1230": Logic 1->Phys 0; Logic 2->Phys 1; Logic 3->Phys 2; Logic 0->Phys 3;
> +     "0321": Logic 0->Phys 0; Logic 3->Phys 1; Logic 2->Phys 2; Logic 1->Phys 3;
> +     "1032": Logic 1->Phys 0; Logic 0->Phys 1; Logic 3->Phys 2; Logic 2->Phys 3;
> +     "2103": Logic 2->Phys 0; Logic 1->Phys 1; Logic 0->Phys 2; Logic 3->Phys 3;
> +     "3210": Logic 3->Phys 0; Logic 2->Phys 1; Logic 1->Phys 2; Logic 0->Phys 3;
> +
> +     Here, a "3012" mapping will be represented by:
> +     lanes = <0 1 8 9 2 3 4 5 6 7>;

I'm lost here. What does 8 mean for example. The index represents?

Rob
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