linux-kernel - Re: [PATCH 1/2] drm/bridge: sii902x: Provide data-lines property to input endpoint

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Message-ID: <6523649b-9143-42d8-b301-a143088530b9@intel.com>
Date: Thu, 3 Oct 2024 15:13:02 +0530
From: Aradhya Bhatia <aradhya.bhatia@...el.com>
To: Wadim Egorov <w.egorov@...tec.de>, andrzej.hajda@...el.com,
 neil.armstrong@...aro.org, rfoss@...nel.org
Cc: Laurent.pinchart@...asonboard.com, jonas@...boo.se,
 jernej.skrabec@...il.com, maarten.lankhorst@...ux.intel.com,
 mripard@...nel.org, tzimmermann@...e.de, airlied@...il.com, simona@...ll.ch,
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
 devicetree@...r.kernel.org, bbrezillon@...nel.org, conor+dt@...nel.org,
 krzk+dt@...nel.org, robh@...nel.org, upstream@...ts.phytec.de
Subject: Re: [PATCH 1/2] drm/bridge: sii902x: Provide data-lines property to
 input endpoint

Hi Wadim,

Thanks for the patch.

Probably a nit, but the dt-binding patch should come before the driver
patch.

On 03-10-2024 13:50, Wadim Egorov wrote:
> Introduce a data-lines property to define the number of parallel RGB
> input pins connected to the transmitter. The input bus formats are updated
> accordingly. If the property is not specified, default to 24 data lines.
> 
> Signed-off-by: Wadim Egorov <w.egorov@...tec.de>
> ---
>  drivers/gpu/drm/bridge/sii902x.c | 27 ++++++++++++++++++++++++++-
>  1 file changed, 26 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/bridge/sii902x.c b/drivers/gpu/drm/bridge/sii902x.c
> index 7f91b0db161e..3565c3533597 100644
> --- a/drivers/gpu/drm/bridge/sii902x.c
> +++ b/drivers/gpu/drm/bridge/sii902x.c
> @@ -180,6 +180,8 @@ struct sii902x {
>  	struct gpio_desc *reset_gpio;
>  	struct i2c_mux_core *i2cmux;
>  	bool sink_is_hdmi;
> +	u32 pd_lines; /* number of Parallel Port Input Data Lines */
> +
>  	/*
>  	 * Mutex protects audio and video functions from interfering
>  	 * each other, by keeping their i2c command sequences atomic.
> @@ -477,6 +479,8 @@ static u32 *sii902x_bridge_atomic_get_input_bus_fmts(struct drm_bridge *bridge,
>  						     u32 output_fmt,
>  						     unsigned int *num_input_fmts)
>  {
> +
> +	struct sii902x *sii902x = bridge_to_sii902x(bridge);
>  	u32 *input_fmts;
>  
>  	*num_input_fmts = 0;
> @@ -485,7 +489,19 @@ static u32 *sii902x_bridge_atomic_get_input_bus_fmts(struct drm_bridge *bridge,
>  	if (!input_fmts)
>  		return NULL;
>  
> -	input_fmts[0] = MEDIA_BUS_FMT_RGB888_1X24;
> +	switch (sii902x->pd_lines) {
> +	case 16:
> +		input_fmts[0] = MEDIA_BUS_FMT_RGB565_1X16;
> +		break;
> +	case 18:
> +		input_fmts[0] = MEDIA_BUS_FMT_RGB666_1X18;
> +		break;
> +	default:

For backward compatibility - in cases where the property is absent - you
have already defaulted sii902x->pd_lines to 24 below, which I think is
the right way.

So, the default case should be kept separately, as an error case -
which should then return back NULL / num_input_fmts = 0.

> +	case 24:
> +		input_fmts[0] = MEDIA_BUS_FMT_RGB888_1X24;
> +		break;
> +	}
> +
>  	*num_input_fmts = 1;
>  
>  	return input_fmts;
> @@ -1167,6 +1183,15 @@ static int sii902x_probe(struct i2c_client *client)
>  		return PTR_ERR(sii902x->reset_gpio);
>  	}
>
> +	endpoint = of_graph_get_endpoint_by_regs(dev->of_node, 0, -1);
> +	if (endpoint) {
> +		ret = of_property_read_u32(endpoint, "data-lines", &sii902x->pd_lines);
> +		if (ret) {
> +			dev_dbg(dev, "Could not get data-lines, fallback to 24 data-lines\n");
> +			sii902x->pd_lines = 24;
> +		}
> +	}
> +
>  	endpoint = of_graph_get_endpoint_by_regs(dev->of_node, 1, -1);
>  	if (endpoint) {
>  		struct device_node *remote = of_graph_get_remote_port_parent(endpoint);

--
Regards
Aradhya