linux-kernel - Re: [PATCH 2/5] drm/panel: mantix: Improve power on sequence timings

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Message-ID: <838b799c-5dfa-4efe-956a-ad5bf16826d6@linaro.org>
Date: Tue, 6 Jan 2026 09:14:42 +0100
From: Neil Armstrong <neil.armstrong@...aro.org>
To: sebastian.krzyszkowiak@...i.sm, Guido Günther
 <agx@...xcpu.org>, Purism Kernel Team <kernel@...i.sm>,
 Jessica Zhang <jesszhan0024@...il.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/5] drm/panel: mantix: Improve power on sequence timings

On 1/5/26 21:24, Sebastian Krzyszkowiak via B4 Relay wrote:
> From: Sebastian Krzyszkowiak <sebastian.krzyszkowiak@...i.sm>
> 
> FP8006P datasheet mentions:
> 
>> It is necessary to wait 15msec after releasing RESX before sending
>> commands. Also Sleep Out command cannot be sent for 120 msec.
> 
> This hasn't been respected by the driver so far, which could interfere
> with the LCD init code sequence performed by the controller. In some cases
> this leads to VCOM voltage being set to a wrong value, causing "halo"
> effects, temporary burn-in around the edges of the screen and degraded
> image contrast.
> 
> T3 and T4 are counted from when VDDI is enabled. There's no need to add
> them when we've already waited more than that in T2 and T2d.
> 
> While FT8006P datasheet does not mention a delay between exiting sleep
> mode and turning the display on, code provided by the vendor uses 120ms
> there and it happens to be the same value as required in newer datasheets
> for newer controllers from the same family, so it seems appropriate to
> use it here as well.
> 
> Signed-off-by: Sebastian Krzyszkowiak <sebastian.krzyszkowiak@...i.sm>
> ---
>   drivers/gpu/drm/panel/panel-mantix-mlaf057we51.c | 13 +++++++------
>   1 file changed, 7 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panel/panel-mantix-mlaf057we51.c b/drivers/gpu/drm/panel/panel-mantix-mlaf057we51.c
> index fafd80f3e952..bb5489e4d7a9 100644
> --- a/drivers/gpu/drm/panel/panel-mantix-mlaf057we51.c
> +++ b/drivers/gpu/drm/panel/panel-mantix-mlaf057we51.c
> @@ -58,11 +58,9 @@ static void mantix_init_sequence(struct mipi_dsi_multi_context *dsi_ctx)
>   
>   	mipi_dsi_generic_write_seq_multi(dsi_ctx, MANTIX_CMD_OTP_STOP_RELOAD_MIPI, 0x5a, 0x09);
>   	mipi_dsi_generic_write_seq_multi(dsi_ctx, 0x80, 0x64, 0x00, 0x64, 0x00, 0x00);
> -	mipi_dsi_msleep(dsi_ctx, 20);
>   
>   	mipi_dsi_generic_write_seq_multi(dsi_ctx, MANTIX_CMD_SPI_FINISH, 0xa5);
>   	mipi_dsi_generic_write_seq_multi(dsi_ctx, MANTIX_CMD_OTP_STOP_RELOAD_MIPI, 0x00, 0x2f);
> -	mipi_dsi_msleep(dsi_ctx, 20);
>   }
>   
>   static int mantix_enable(struct drm_panel *panel)
> @@ -75,8 +73,11 @@ static int mantix_enable(struct drm_panel *panel)
>   	if (!dsi_ctx.accum_err)
>   		dev_dbg(ctx->dev, "Panel init sequence done\n");
>   
> +	/* remainder to 120ms (7.3.1 Note 4) */
> +	mipi_dsi_msleep(&dsi_ctx, 70);
> +
>   	mipi_dsi_dcs_exit_sleep_mode_multi(&dsi_ctx);
> -	mipi_dsi_msleep(&dsi_ctx, 20);
> +	mipi_dsi_msleep(&dsi_ctx, 120);
>   
>   	mipi_dsi_dcs_set_display_on_multi(&dsi_ctx);
>   	mipi_dsi_usleep_range(&dsi_ctx, 10000, 12000);
> @@ -147,10 +148,10 @@ static int mantix_prepare(struct drm_panel *panel)
>   		return ret;
>   	}
>   
> -	/* T3 + T4 + time for voltage to become stable: */
> -	usleep_range(6000, 7000);
> -	gpiod_set_value_cansleep(ctx->reset_gpio, 0);
> +	usleep_range(100, 200);
>   	gpiod_set_value_cansleep(ctx->tp_rstn_gpio, 0);
> +	usleep_range(100, 200);
> +	gpiod_set_value_cansleep(ctx->reset_gpio, 0);
>   
>   	/* T6 */
>   	msleep(50);
> 

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

Thanks,
Neil