Re: [RFC PATCH 05/14] ARM: dts: samsung-fimd: add I80 specific properties

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi YoungJun,

Thank you for the patch.

On Tuesday 15 April 2014 14:47:33 YoungJun Cho wrote:
> In case of using CPU interface panel, the relevant registers should be set.
> So this patch adds relevant dt bindings.
> 
> Signed-off-by: YoungJun Cho <yj44.cho@samsung.com>
> Signed-off-by: Inki Dae <inki.dae@samsung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
> ---
>  .../devicetree/bindings/video/samsung-fimd.txt     |    9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/video/samsung-fimd.txt
> b/Documentation/devicetree/bindings/video/samsung-fimd.txt index
> 2dad41b..924c2e1 100644
> --- a/Documentation/devicetree/bindings/video/samsung-fimd.txt
> +++ b/Documentation/devicetree/bindings/video/samsung-fimd.txt
> @@ -44,6 +44,15 @@ Optional Properties:
>  - display-timings: timing settings for FIMD, as described in document [1].
>  		Can be used in case timings cannot be provided otherwise
>  		or to override timings provided by the panel.
> +- samsung,sysreg-phandle: handle to syscon used to control the system
> registers +- vidout-i80-ldi: boolean to support i80 interface instead of
> rgb one +- cs-setup: clock cycles for the active period of address signal
> enable until +	chip select is enable in i80 interface
> +- wr-setup: clock cycles for the active period of CS signal enable until
> +	write signal is enable in i80 interface
> +- wr-act: clock cycles for the active period of CS enable in i80 interface
> +- wr-hold: clock cycles for the active period of CS disable until write
> signal +	is disable in i80 interface

Shouldn't the interface parameters be considered as a property of the slave 
device instead ? The bus master side is programmable, and different slaves 
would have different timing requirements. I think it would make more sense to 
specify the timings on the slave (panel) side and query them dynamically at 
runtime. Depending on the slave the timings could be hardcoded in the driver 
(as they're usually an intrinsic property of the slave) or partially or fully 
specified in the slave DT node.

>  The device node can contain 'port' child nodes according to the bindings
> defined in [2]. The following are properties specific to those nodes:

-- 
Regards,

Laurent Pinchart