linux-kernel - Re: [PATCH v2 3/4] drm/panel: sitronix-st7789v: add support for partial mode

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Date:   Fri, 4 Aug 2023 15:06:50 +0200
From:   Neil Armstrong <neil.armstrong@...aro.org>
To:     Michael Riesch <michael.riesch@...fvision.net>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Sam Ravnborg <sam@...nborg.org>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Maxime Ripard <mripard@...nel.org>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Sebastian Reichel <sre@...nel.org>,
        Gerald Loacker <gerald.loacker@...fvision.net>
Cc:     devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH v2 3/4] drm/panel: sitronix-st7789v: add support for
 partial mode

On 04/08/2023 15:02, Michael Riesch wrote:
> The ST7789V controller features support for the partial mode. Here,
> the area to be displayed can be restricted in one direction (by default,
> in vertical direction). This is useful for panels that are partially
> occluded by design. Add support for the partial mode.
> 
> Signed-off-by: Michael Riesch <michael.riesch@...fvision.net>
> ---
>   drivers/gpu/drm/panel/panel-sitronix-st7789v.c | 43 ++++++++++++++++++++++++--
>   1 file changed, 41 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panel/panel-sitronix-st7789v.c b/drivers/gpu/drm/panel/panel-sitronix-st7789v.c
> index 0ded72ed2fcd..ebc9a3bd6db3 100644
> --- a/drivers/gpu/drm/panel/panel-sitronix-st7789v.c
> +++ b/drivers/gpu/drm/panel/panel-sitronix-st7789v.c
> @@ -118,6 +118,9 @@ struct st7789_panel_info {
>   	u32 bus_format;
>   	u32 bus_flags;
>   	bool invert_mode;
> +	bool partial_mode;
> +	u16 partial_start;
> +	u16 partial_end;
>   };
>   
>   struct st7789v {
> @@ -345,9 +348,14 @@ static enum drm_panel_orientation st7789v_get_orientation(struct drm_panel *p)
>   static int st7789v_prepare(struct drm_panel *panel)
>   {
>   	struct st7789v *ctx = panel_to_st7789v(panel);
> -	u8 pixel_fmt, polarity;
> +	u8 mode, pixel_fmt, polarity;
>   	int ret;
>   
> +	if (!ctx->info->partial_mode)
> +		mode = ST7789V_RGBCTRL_WO;
> +	else
> +		mode = 0;
> +
>   	switch (ctx->info->bus_format) {
>   	case MEDIA_BUS_FMT_RGB666_1X18:
>   		pixel_fmt = MIPI_DCS_PIXEL_FMT_18BIT;
> @@ -487,6 +495,37 @@ static int st7789v_prepare(struct drm_panel *panel)
>   						MIPI_DCS_EXIT_INVERT_MODE));
>   	}
>   
> +	if (ctx->info->partial_mode) {
> +		u8 area_data[4] = {
> +			(ctx->info->partial_start >> 8) & 0xff,
> +			(ctx->info->partial_start >> 0) & 0xff,
> +			((ctx->info->partial_end - 1) >> 8) & 0xff,
> +			((ctx->info->partial_end - 1) >> 0) & 0xff,
> +		};
> +
> +		/* Caution: if userspace ever pushes a mode different from the
> +		 * expected one (i.e., the one advertised by get_modes), we'll
> +		 * add margins.
> +		 */
> +
> +		ST7789V_TEST(ret, st7789v_write_command(
> +					  ctx, MIPI_DCS_ENTER_PARTIAL_MODE));
> +
> +		ST7789V_TEST(ret, st7789v_write_command(
> +					  ctx, MIPI_DCS_SET_PAGE_ADDRESS));
> +		ST7789V_TEST(ret, st7789v_write_data(ctx, area_data[0]));
> +		ST7789V_TEST(ret, st7789v_write_data(ctx, area_data[1]));
> +		ST7789V_TEST(ret, st7789v_write_data(ctx, area_data[2]));
> +		ST7789V_TEST(ret, st7789v_write_data(ctx, area_data[3]));
> +
> +		ST7789V_TEST(ret, st7789v_write_command(
> +					  ctx, MIPI_DCS_SET_PARTIAL_ROWS));
> +		ST7789V_TEST(ret, st7789v_write_data(ctx, area_data[0]));
> +		ST7789V_TEST(ret, st7789v_write_data(ctx, area_data[1]));
> +		ST7789V_TEST(ret, st7789v_write_data(ctx, area_data[2]));
> +		ST7789V_TEST(ret, st7789v_write_data(ctx, area_data[3]));
> +	}
> +
>   	ST7789V_TEST(ret, st7789v_write_command(ctx, ST7789V_RAMCTRL_CMD));
>   	ST7789V_TEST(ret, st7789v_write_data(ctx, ST7789V_RAMCTRL_DM_RGB |
>   					     ST7789V_RAMCTRL_RM_RGB));
> @@ -494,7 +533,7 @@ static int st7789v_prepare(struct drm_panel *panel)
>   					     ST7789V_RAMCTRL_MAGIC));
>   
>   	ST7789V_TEST(ret, st7789v_write_command(ctx, ST7789V_RGBCTRL_CMD));
> -	ST7789V_TEST(ret, st7789v_write_data(ctx, ST7789V_RGBCTRL_WO |
> +	ST7789V_TEST(ret, st7789v_write_data(ctx, mode |
>   					     ST7789V_RGBCTRL_RCM(2) |
>   					     polarity));
>   	ST7789V_TEST(ret, st7789v_write_data(ctx, ST7789V_RGBCTRL_VBP(8)));
> 

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