linux-kernel - Re: [PATCH] drm/panel: boe-tv101wum-nl6: Completely Pull GPW to VGL before TP term

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Date:   Fri, 15 Sep 2023 11:17:54 -0700
From:   Jessica Zhang <quic_jesszhan@...cinc.com>
To:     Ruihai Zhou <zhouruihai@...qin.corp-partner.google.com>,
        <neil.armstrong@...aro.org>, <sam@...nborg.org>,
        <airlied@...il.com>, <daniel@...ll.ch>
CC:     <dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>,
        <linus.walleij@...aro.org>
Subject: Re: [PATCH] drm/panel: boe-tv101wum-nl6: Completely Pull GPW to VGL
 before TP term



On 9/12/2023 3:59 AM, Ruihai Zhou wrote:
> The sta_himax83102 panel sometimes shows abnormally flickering
> horizontal lines. The front gate output will precharge the X point of
> the next pole circuit before TP(TouchPanel Enable) term starts, and wait
> until the end of the TP term to resume the CLK. For this reason, the X
> point must be maintained during the TP term. In abnormal case, we
> measured a slight leakage at point X. This because during the TP term,
> the GPW does not fully pull the VGL low, causing the TFT to not be
> closed tightly.
> 
> To fix this, we completely pull GPW to VGL before entering the TP term.
> This will ensure that the TFT is closed tightly and prevent the abnormal
> display.

Hi Ruihai,

Can you add a fixes-by tag?
I think this might be the one to use:

Fixes: 1bc2ef065f13 ("drm/panel: Support for Starry-himax83102-j02 TDDI 
MIPI-DSI panel")

Otherwise this LGTM.

Reviewed-by: Jessica Zhang <quic_jesszhan@...cinc.com>

Thanks,

Jessica Zhang

> 
> Signed-off-by: Ruihai Zhou <zhouruihai@...qin.corp-partner.google.com>
> ---
> This patch base on original fixes series [1]
> [1] https://patchwork.kernel.org/project/dri-devel/cover/20230703-fix-boe-tv101wum-nl6-v3-0-bd6e9432c755@linaro.org/
> ---
>   drivers/gpu/drm/panel/panel-boe-tv101wum-nl6.c | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panel/panel-boe-tv101wum-nl6.c b/drivers/gpu/drm/panel/panel-boe-tv101wum-nl6.c
> index c2ee2c6b4150..e37b9b4f528d 100644
> --- a/drivers/gpu/drm/panel/panel-boe-tv101wum-nl6.c
> +++ b/drivers/gpu/drm/panel/panel-boe-tv101wum-nl6.c
> @@ -1305,9 +1305,8 @@ static int starry_himax83102_j02_init(struct mipi_dsi_device *dsi)
>   	mipi_dsi_dcs_write_seq(dsi, 0xB1, 0x01, 0xBF, 0x11);
>   	mipi_dsi_dcs_write_seq(dsi, 0xCB, 0x86);
>   	mipi_dsi_dcs_write_seq(dsi, 0xD2, 0x3C, 0xFA);
> -	mipi_dsi_dcs_write_seq(dsi, 0xE9, 0xC5);
> -	mipi_dsi_dcs_write_seq(dsi, 0xD3, 0x00, 0x00, 0x00, 0x00, 0x80, 0x0C, 0x01);
> -	mipi_dsi_dcs_write_seq(dsi, 0xE9, 0x3F);
> +	mipi_dsi_dcs_write_seq(dsi, 0xD3, 0x00, 0x00, 0x44, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80,
> +			       0x0C, 0x01);
>   	mipi_dsi_dcs_write_seq(dsi, 0xE7, 0x02, 0x00, 0x28, 0x01, 0x7E, 0x0F, 0x7E, 0x10, 0xA0,
>   			       0x00, 0x00, 0x20, 0x40, 0x50, 0x40);
>   	mipi_dsi_dcs_write_seq(dsi, 0xBD, 0x02);
> -- 
> 2.17.1
>