linux-kernel - Re: [PATCH] drm/bridge: nwl-dsi: Use vsync/hsync polarity from display mode

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Message-ID: <ba9c9e9e-006e-40c8-b4cf-45dc08a5ea57@linaro.org>
Date: Fri, 13 Sep 2024 09:55:55 +0200
From: Neil Armstrong <neil.armstrong@...aro.org>
To: Esben Haabendal <esben@...nix.com>,
 Andrzej Hajda <andrzej.hajda@...el.com>, Robert Foss <rfoss@...nel.org>,
 Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
 Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/bridge: nwl-dsi: Use vsync/hsync polarity from
 display mode

On 14/08/2024 12:37, Esben Haabendal wrote:
> Using the correct bit helps. The documentation specifies bit 0 in both
> registers to be controlling polarity of dpi_vsync_input and
> dpi_hsync_input polarity. Bit 1 is reserved, and should therefore not be
> set.
> 
> Tested with panel that requires active high vsync and hsync.
> 
> Signed-off-by: Esben Haabendal <esben@...nix.com>
> ---
>   drivers/gpu/drm/bridge/nwl-dsi.c | 8 ++++----
>   drivers/gpu/drm/bridge/nwl-dsi.h | 4 ++--
>   2 files changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/nwl-dsi.c b/drivers/gpu/drm/bridge/nwl-dsi.c
> index 8d54091ec66e..5f05647a3bea 100644
> --- a/drivers/gpu/drm/bridge/nwl-dsi.c
> +++ b/drivers/gpu/drm/bridge/nwl-dsi.c
> @@ -289,13 +289,13 @@ static int nwl_dsi_config_dpi(struct nwl_dsi *dsi)
>   
>   	nwl_dsi_write(dsi, NWL_DSI_INTERFACE_COLOR_CODING, NWL_DSI_DPI_24_BIT);
>   	nwl_dsi_write(dsi, NWL_DSI_PIXEL_FORMAT, color_format);
> -	/*
> -	 * Adjusting input polarity based on the video mode results in
> -	 * a black screen so always pick active low:
> -	 */
>   	nwl_dsi_write(dsi, NWL_DSI_VSYNC_POLARITY,
> +		      dsi->mode.flags & DRM_MODE_FLAG_PVSYNC ?
> +		      NWL_DSI_VSYNC_POLARITY_ACTIVE_HIGH :
>   		      NWL_DSI_VSYNC_POLARITY_ACTIVE_LOW);
>   	nwl_dsi_write(dsi, NWL_DSI_HSYNC_POLARITY,
> +		      dsi->mode.flags & DRM_MODE_FLAG_PHSYNC ?
> +		      NWL_DSI_HSYNC_POLARITY_ACTIVE_HIGH :
>   		      NWL_DSI_HSYNC_POLARITY_ACTIVE_LOW);
>   
>   	burst_mode = (dsi->dsi_mode_flags & MIPI_DSI_MODE_VIDEO_BURST) &&
> diff --git a/drivers/gpu/drm/bridge/nwl-dsi.h b/drivers/gpu/drm/bridge/nwl-dsi.h
> index a247a8a11c7c..61e7d65cb1eb 100644
> --- a/drivers/gpu/drm/bridge/nwl-dsi.h
> +++ b/drivers/gpu/drm/bridge/nwl-dsi.h
> @@ -30,11 +30,11 @@
>   #define NWL_DSI_PIXEL_FORMAT			0x20c
>   #define NWL_DSI_VSYNC_POLARITY			0x210
>   #define NWL_DSI_VSYNC_POLARITY_ACTIVE_LOW	0
> -#define NWL_DSI_VSYNC_POLARITY_ACTIVE_HIGH	BIT(1)
> +#define NWL_DSI_VSYNC_POLARITY_ACTIVE_HIGH	BIT(0)
>   
>   #define NWL_DSI_HSYNC_POLARITY			0x214
>   #define NWL_DSI_HSYNC_POLARITY_ACTIVE_LOW	0
> -#define NWL_DSI_HSYNC_POLARITY_ACTIVE_HIGH	BIT(1)
> +#define NWL_DSI_HSYNC_POLARITY_ACTIVE_HIGH	BIT(0)
>   
>   #define NWL_DSI_VIDEO_MODE			0x218
>   #define NWL_DSI_HFP				0x21c
> 
> ---
> base-commit: 7c626ce4bae1ac14f60076d00eafe71af30450ba
> change-id: 20240814-nwl-dsi-sync-polarity-ddc58435a4c4
> 
> Best regards,

Reviewed-by: Neil Armstrong <neil.armstrong@...aro.org>