Re: [PATCH 2/2] drm/panel: boe-tv101wum-nl6: Reduce lcm_reset to send initial code time

From: "Xinlei Lee (李昕磊)" <Xinlei.Lee@mediatek.com>
To: "sam@ravnborg.org" <sam@ravnborg.org>
Cc: "chunkuang.hu@kernel.org" <chunkuang.hu@kernel.org>,
	"Jitao Shi (石记涛)" <jitao.shi@mediatek.com>,
	"airlied@linux.ie" <airlied@linux.ie>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"dri-devel@lists.freedesktop.org"
	<dri-devel@lists.freedesktop.org>,
	Project_Global_Chrome_Upstream_Group
	<Project_Global_Chrome_Upstream_Group@mediatek.com>,
	"thierry.reding@gmail.com" <thierry.reding@gmail.com>,
	"linux-mediatek@lists.infradead.org"
	<linux-mediatek@lists.infradead.org>,
	"matthias.bgg@gmail.com" <matthias.bgg@gmail.com>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"angelogioacchino.delregno@collabora.com"
	<angelogioacchino.delregno@collabora.com>
Subject: Re: [PATCH 2/2] drm/panel: boe-tv101wum-nl6: Reduce lcm_reset to send initial code time
Date: Mon, 9 Jan 2023 11:58:34 +0000	[thread overview]
Message-ID: <3aa9243afc5fa8484bfe2db0b566ada24257edbe.camel@mediatek.com> (raw)
In-Reply-To: <Y7nWhciY7cru78lQ@ravnborg.org>

[-- Attachment #1: Type: text/html, Size: 4309 bytes --]

[-- Attachment #2: Type: text/plain, Size: 2011 bytes --]

On Sat, 2023-01-07 at 21:31 +0100, Sam Ravnborg wrote:
> On Fri, Jan 06, 2023 at 11:05:21AM +0800, xinlei.lee@mediatek.com
> wrote:
> > From: Xinlei Lee <xinlei.lee@mediatek.com>
> > 
> > Since the panel spec stipulates that the time from lcm_reset to DSI
> > to
> > send the initial code should be greater than 6ms and less than
> > 40ms,
> > so reduce the delay before sending the initial code and avoid panel
> > exceptions.
> 
> The changelog says "reduce the delay", but the patch removes the
> delay.
> Are there other delays that make sure the "greater than 6 ms" is OK?
> 
> 	Sam
> 
> > 
> > Fixes: a869b9db7adf ("drm/panel: support for boe tv101wum-nl6 wuxga
> > dsi video mode panel")
> > Signed-off-by: Xinlei Lee <xinlei.lee@mediatek.com>
> > ---
> >  drivers/gpu/drm/panel/panel-boe-tv101wum-nl6.c | 1 -
> >  1 file changed, 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/panel/panel-boe-tv101wum-nl6.c
> > b/drivers/gpu/drm/panel/panel-boe-tv101wum-nl6.c
> > index 857a2f0420d7..f0093035f1ff 100644
> > --- a/drivers/gpu/drm/panel/panel-boe-tv101wum-nl6.c
> > +++ b/drivers/gpu/drm/panel/panel-boe-tv101wum-nl6.c
> > @@ -780,7 +780,6 @@ static const struct panel_init_cmd
> > inx_hj110iz_init_cmd[] = {
> >  };
> >  
> >  static const struct panel_init_cmd boe_init_cmd[] = {
> > -	_INIT_DELAY_CMD(24),
> >  	_INIT_DCS_CMD(0xB0, 0x05),
> >  	_INIT_DCS_CMD(0xB1, 0xE5),
> >  	_INIT_DCS_CMD(0xB3, 0x52),
> > -- 
> > 2.18.0

Hi Sam:

Thanks for your reply!

Please allow me to explain, in the boe_panel_prepare function in this 
file, there will be a 6ms delay after the reset pin is pulled high 
(gpiod_set_value(boe->enable_gpio, 1)), and the initial code will be 
sent in the boe_panel_init_dcs_cmd function later, This period of time 
ensures that the delay is within the specified range.

In addition, I will add a special panel control in the V2 version, if 
you have any questions, we will discuss it later.

Best Regards!
xinlei