linux-kernel - Re: [PATCH] drm/bridge: add it6505 driver read config from dt property

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Message-ID: <19a3fd3b-ec9a-6b8e-5a79-46ff13f8f4e5@baylibre.com>
Date:   Mon, 27 Jun 2022 14:18:56 +0200
From:   Neil Armstrong <narmstrong@...libre.com>
To:     allen <allen.chen@....com.tw>
Cc:     Pin-yen Lin <treapking@...gle.com>,
        Jau-Chih Tseng <Jau-Chih.Tseng@....com.tw>,
        Hermes Wu <Hermes.Wu@....com.tw>,
        Kenneth Hung <Kenneth.Hung@....com.tw>,
        Pin-yen Lin <treapking@...omium.org>,
        Andrzej Hajda <andrzej.hajda@...el.com>,
        Robert Foss <robert.foss@...aro.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        "open list:DRM DRIVERS" <dri-devel@...ts.freedesktop.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/bridge: add it6505 driver read config from dt
 property

On 27/06/2022 07:40, allen wrote:
> From: allen chen <allen.chen@....com.tw>
> 
> add read max-lane and max-pixel-clock from dt property

Those 2 properties should be documented first in the DT bindings.

Neil

> 
> Signed-off-by: Allen Chen <allen.chen@....com.tw>
> Signed-off-by: Pin-yen Lin <treapking@...omium.org>
> ---
>   drivers/gpu/drm/bridge/ite-it6505.c | 35 ++++++++++++++++++++++++++---
>   1 file changed, 32 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
> index 4b673c4792d77..c9121d4635a52 100644
> --- a/drivers/gpu/drm/bridge/ite-it6505.c
> +++ b/drivers/gpu/drm/bridge/ite-it6505.c
> @@ -436,6 +436,8 @@ struct it6505 {
>   	bool powered;
>   	bool hpd_state;
>   	u32 afe_setting;
> +	u32 max_dpi_pixel_clock;
> +	u32 max_lane_count;
>   	enum hdcp_state hdcp_status;
>   	struct delayed_work hdcp_work;
>   	struct work_struct hdcp_wait_ksv_list;
> @@ -1466,7 +1468,8 @@ static void it6505_parse_link_capabilities(struct it6505 *it6505)
>   	it6505->lane_count = link->num_lanes;
>   	DRM_DEV_DEBUG_DRIVER(dev, "Sink support %d lanes training",
>   			     it6505->lane_count);
> -	it6505->lane_count = min_t(int, it6505->lane_count, MAX_LANE_COUNT);
> +	it6505->lane_count = min_t(int, it6505->lane_count,
> +				   it6505->max_lane_count);
>   
>   	it6505->branch_device = drm_dp_is_branch(it6505->dpcd);
>   	DRM_DEV_DEBUG_DRIVER(dev, "Sink %sbranch device",
> @@ -2895,7 +2898,7 @@ it6505_bridge_mode_valid(struct drm_bridge *bridge,
>   	if (mode->flags & DRM_MODE_FLAG_INTERLACE)
>   		return MODE_NO_INTERLACE;
>   
> -	if (mode->clock > DPI_PIXEL_CLK_MAX)
> +	if (mode->clock > it6505->max_dpi_pixel_clock)
>   		return MODE_CLOCK_HIGH;
>   
>   	it6505->video_info.clock = mode->clock;
> @@ -3057,6 +3060,8 @@ static void it6505_parse_dt(struct it6505 *it6505)
>   {
>   	struct device *dev = &it6505->client->dev;
>   	u32 *afe_setting = &it6505->afe_setting;
> +	u32 *max_lane_count = &it6505->max_lane_count;
> +	u32 *max_dpi_pixel_clock = &it6505->max_dpi_pixel_clock;
>   
>   	it6505->lane_swap_disabled =
>   		device_property_read_bool(dev, "no-laneswap");
> @@ -3072,7 +3077,31 @@ static void it6505_parse_dt(struct it6505 *it6505)
>   	} else {
>   		*afe_setting = 0;
>   	}
> -	DRM_DEV_DEBUG_DRIVER(dev, "using afe_setting: %d", *afe_setting);
> +
> +	if (device_property_read_u32(dev, "max-lane-count",
> +				     max_lane_count) == 0) {
> +		if (*max_lane_count > 4 || *max_lane_count == 3) {
> +			dev_err(dev, "max lane count error, use default");
> +			*max_lane_count = MAX_LANE_COUNT;
> +		}
> +	} else {
> +		*max_lane_count = MAX_LANE_COUNT;
> +	}
> +
> +	if (device_property_read_u32(dev, "max-dpi-pixel-clock",
> +				     max_dpi_pixel_clock) == 0) {
> +		if (*max_dpi_pixel_clock > 297000) {
> +			dev_err(dev, "max pixel clock error, use default");
> +			*max_dpi_pixel_clock = DPI_PIXEL_CLK_MAX;
> +		}
> +	} else {
> +		*max_dpi_pixel_clock = DPI_PIXEL_CLK_MAX;
> +	}
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "using afe_setting: %u, max_lane_count: %u",
> +			     it6505->afe_setting, it6505->max_lane_count);
> +	DRM_DEV_DEBUG_DRIVER(dev, "using max_dpi_pixel_clock: %u kHz",
> +			     it6505->max_dpi_pixel_clock);
>   }
>   
>   static ssize_t receive_timing_debugfs_show(struct file *file, char __user *buf,