Re: [PATCH v3 3/6] drm/bridge: tc358767: Drop line_pixel_subtract

[Alexander Stein <alexander.stein@ew.tq-group.com>]

Am Sonntag, 23. Juni 2024, 16:38:35 CEST schrieb Marek Vasut:
> This line_pixel_subtract is no longer needed now that the bridge can
> request and obtain specific pixel clock on input to the bridge, with
> clock frequency that matches the Pixel PLL frequency.
> 
> The line_pixel_subtract is now always 0, so drop it entirely.
> 
> The line_pixel_subtract was not reliable as it never worked when the
> Pixel PLL and input clock were off just so that the required amount
> of pixels to subtract would not be whole integer.
> 
> Signed-off-by: Marek Vasut <marex@denx.de>

For me is even necessary to get the DP test mode running, using DSI as input.
With the removal of div64_round_up() from patch 1 addeded here:
Reviewed-by: Alexander Stein <alexander.stein@ew.tq-group.com>

> ---
> Cc: Andrzej Hajda <andrzej.hajda@intel.com>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: David Airlie <airlied@gmail.com>
> Cc: Jernej Skrabec <jernej.skrabec@gmail.com>
> Cc: Jonas Karlman <jonas@kwiboo.se>
> Cc: Laurent Pinchart <Laurent.pinchart@ideasonboard.com>
> Cc: Lucas Stach <l.stach@pengutronix.de>
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Cc: Maxime Ripard <mripard@kernel.org>
> Cc: Neil Armstrong <neil.armstrong@linaro.org>
> Cc: Robert Foss <rfoss@kernel.org>
> Cc: Thomas Zimmermann <tzimmermann@suse.de>
> Cc: dri-devel@lists.freedesktop.org
> Cc: kernel@dh-electronics.com
> ---
> V2: No change
> V3: Fix up rebase artifact
> ---
>  drivers/gpu/drm/bridge/tc358767.c | 16 +---------------
>  1 file changed, 1 insertion(+), 15 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/tc358767.c b/drivers/gpu/drm/bridge/tc358767.c
> index 20be21660ba76..c4e2455ad95e4 100644
> --- a/drivers/gpu/drm/bridge/tc358767.c
> +++ b/drivers/gpu/drm/bridge/tc358767.c
> @@ -382,9 +382,6 @@ struct tc_data {
>  
>  	/* HPD pin number (0 or 1) or -ENODEV */
>  	int			hpd_pin;
> -
> -	/* Number of pixels to subtract from a line due to pixel clock delta */
> -	u32			line_pixel_subtract;
>  };
>  
>  static inline struct tc_data *aux_to_tc(struct drm_dp_aux *a)
> @@ -661,11 +658,7 @@ static int tc_pxl_pll_calc(struct tc_data *tc, u32 refclk, u32 pixelclock,
>  		return -EINVAL;
>  	}
>  
> -	tc->line_pixel_subtract = tc->mode.htotal -
> -		div64_round_up(tc->mode.htotal * (u64)best_pixelclock, pixelclock);
> -
> -	dev_dbg(tc->dev, "PLL: got %d, delta %d (subtract %d px)\n", best_pixelclock,
> -		best_delta, tc->line_pixel_subtract);
> +	dev_dbg(tc->dev, "PLL: got %d, delta %d\n", best_pixelclock, best_delta);
>  	dev_dbg(tc->dev, "PLL: %d / %d / %d * %d / %d\n", refclk,
>  		ext_div[best_pre], best_div, best_mul, ext_div[best_post]);
>  
> @@ -909,13 +902,6 @@ static int tc_set_common_video_mode(struct tc_data *tc,
>  		upper_margin, lower_margin, vsync_len);
>  	dev_dbg(tc->dev, "total: %dx%d\n", mode->htotal, mode->vtotal);
>  
> -	if (right_margin > tc->line_pixel_subtract) {
> -		right_margin -= tc->line_pixel_subtract;
> -	} else {
> -		dev_err(tc->dev, "Bridge pixel clock too slow for mode\n");
> -		right_margin = 0;
> -	}
> -
>  	/*
>  	 * LCD Ctl Frame Size
>  	 * datasheet is not clear of vsdelay in case of DPI
> 


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