linux-kernel - Re: [PATCH 4/8] drm/tidss: Add support for Dual Link LVDS Bus Format

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Date:   Thu, 28 Jul 2022 14:03:53 +0300
From:   Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
To:     Aradhya Bhatia <a-bhatia1@...com>
Cc:     Darren Etheridge <detheridge@...com>, Nishanth Menon <nm@...com>,
        Vignesh Raghavendra <vigneshr@...com>,
        Rahul T R <r-ravikumar@...com>,
        Krunal Bhargav <k-bhargav@...com>,
        Devarsh Thakkar <devarsht@...com>,
        DRI Development List <dri-devel@...ts.freedesktop.org>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Rob Herring <robh+dt@...nel.org>,
        Jyri Sarha <jyri.sarha@....fi>,
        Devicetree List <devicetree@...r.kernel.org>,
        Linux Kernel List <linux-kernel@...r.kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>
Subject: Re: [PATCH 4/8] drm/tidss: Add support for Dual Link LVDS Bus Format

On 19/07/2022 11:08, Aradhya Bhatia wrote:
> The 2 OLDI TXes in the AM625 SoC can be synced together to output a 2K
> resolution video.
> 
> Add support in the driver for the discovery of such a dual mode
> connection on the OLDI video port, using the values of "ti,oldi-mode"
> property.
> 
> Signed-off-by: Aradhya Bhatia <a-bhatia1@...com>
> ---
>   drivers/gpu/drm/tidss/tidss_dispc.c | 39 +++++++++++++++++++++--------
>   1 file changed, 28 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/gpu/drm/tidss/tidss_dispc.c b/drivers/gpu/drm/tidss/tidss_dispc.c
> index add725fa682b..fb1fdecfc83a 100644
> --- a/drivers/gpu/drm/tidss/tidss_dispc.c
> +++ b/drivers/gpu/drm/tidss/tidss_dispc.c
> @@ -853,25 +853,36 @@ void dispc_set_irqenable(struct dispc_device *dispc, dispc_irq_t mask)
>   	}
>   }
>   
> -enum dispc_oldi_mode_reg_val { SPWG_18 = 0, JEIDA_24 = 1, SPWG_24 = 2 };
> +enum dispc_oldi_mode_reg_val {
> +	SPWG_18		= 0,
> +	JEIDA_24	= 1,
> +	SPWG_24		= 2,
> +	DL_SPWG_18	= 4,
> +	DL_JEIDA_24	= 5,
> +	DL_SPWG_24	= 6,
> +};
>   
>   struct dispc_bus_format {
>   	u32 bus_fmt;
>   	u32 data_width;
>   	bool is_oldi_fmt;
> +	bool is_dual_link;
>   	enum dispc_oldi_mode_reg_val oldi_mode_reg_val;
>   };
>   
>   static const struct dispc_bus_format dispc_bus_formats[] = {
> -	{ MEDIA_BUS_FMT_RGB444_1X12,		12, false, 0 },
> -	{ MEDIA_BUS_FMT_RGB565_1X16,		16, false, 0 },
> -	{ MEDIA_BUS_FMT_RGB666_1X18,		18, false, 0 },
> -	{ MEDIA_BUS_FMT_RGB888_1X24,		24, false, 0 },
> -	{ MEDIA_BUS_FMT_RGB101010_1X30,		30, false, 0 },
> -	{ MEDIA_BUS_FMT_RGB121212_1X36,		36, false, 0 },
> -	{ MEDIA_BUS_FMT_RGB666_1X7X3_SPWG,	18, true, SPWG_18 },
> -	{ MEDIA_BUS_FMT_RGB888_1X7X4_SPWG,	24, true, SPWG_24 },
> -	{ MEDIA_BUS_FMT_RGB888_1X7X4_JEIDA,	24, true, JEIDA_24 },
> +	{ MEDIA_BUS_FMT_RGB444_1X12,		12, false, false, 0 },
> +	{ MEDIA_BUS_FMT_RGB565_1X16,		16, false, false, 0 },
> +	{ MEDIA_BUS_FMT_RGB666_1X18,		18, false, false, 0 },
> +	{ MEDIA_BUS_FMT_RGB888_1X24,		24, false, false, 0 },
> +	{ MEDIA_BUS_FMT_RGB101010_1X30,		30, false, false, 0 },
> +	{ MEDIA_BUS_FMT_RGB121212_1X36,		36, false, false, 0 },
> +	{ MEDIA_BUS_FMT_RGB666_1X7X3_SPWG,	18, true, false, SPWG_18 },
> +	{ MEDIA_BUS_FMT_RGB888_1X7X4_SPWG,	24, true, false, SPWG_24 },
> +	{ MEDIA_BUS_FMT_RGB888_1X7X4_JEIDA,	24, true, false, JEIDA_24 },
> +	{ MEDIA_BUS_FMT_RGB666_1X7X3_SPWG,	18, true, true, DL_SPWG_18 },
> +	{ MEDIA_BUS_FMT_RGB888_1X7X4_SPWG,	24, true, true, DL_SPWG_24 },
> +	{ MEDIA_BUS_FMT_RGB888_1X7X4_JEIDA,	24, true, true, DL_JEIDA_24 },
>   };

So the dual link sends two pixels per clock, right? Are there panel or 
bridge drivers that support this? My initial thought was that it should 
be a new bus format.

  Tomi