Re: [PATCH 3/4] drm/panel: himax-hx8394: Add Support for Huiling hl055fhav028c

From: "Heiko Stübner" <heiko@sntech.de>
To: Chris Morgan <macroalpha82@gmail.com>,
	dri-devel@lists.freedesktop.org,
	Diederik de Haas <didi.debian@cknow.org>
Cc: linux-rockchip@lists.infradead.org, devicetree@vger.kernel.org,
	sebastian.reichel@collabora.com, conor+dt@kernel.org,
	krzk+dt@kernel.org, robh@kernel.org, tzimmermann@suse.de,
	mripard@kernel.org, maarten.lankhorst@linux.intel.com,
	simona@ffwll.ch, airlied@gmail.com, quic_jesszhan@quicinc.com,
	neil.armstrong@linaro.org, javierm@redhat.com, megi@xff.cz,
	Chris Morgan <macromorgan@hotmail.com>
Subject: Re: [PATCH 3/4] drm/panel: himax-hx8394: Add Support for Huiling hl055fhav028c
Date: Thu, 05 Jun 2025 14:46:00 +0200	[thread overview]
Message-ID: <2932680.yaVYbkx8dN@diego> (raw)
In-Reply-To: <DAEKVTXT0FHB.TOVX7BU9ZYXA@cknow.org>

Am Donnerstag, 5. Juni 2025, 13:54:50 Mitteleuropäische Sommerzeit schrieb Diederik de Haas:
> On Tue Jun 3, 2025 at 9:39 PM CEST, Chris Morgan wrote:
> > From: Chris Morgan <macromorgan@hotmail.com>
> >
> > Add support for the Huiling hl055fhav028c panel as used on the
> > Gameforce Ace handheld gaming console. This panel uses a Himax HX8399C
> > display controller and requires a sparsely documented vendor provided
> > init sequence. The display resolution is 1080x1920 and is 70mm by 127mm
> > as stated in the manufacturer's documentation.
> >
> > Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
> > ---
> >  drivers/gpu/drm/panel/panel-himax-hx8394.c | 142 +++++++++++++++++++++
> >  1 file changed, 142 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/panel/panel-himax-hx8394.c b/drivers/gpu/drm/panel/panel-himax-hx8394.c
> > index ff994bf0e3cc..16e450b156b7 100644
> > --- a/drivers/gpu/drm/panel/panel-himax-hx8394.c
> > +++ b/drivers/gpu/drm/panel/panel-himax-hx8394.c
> > @@ -477,6 +477,147 @@ static const struct hx8394_panel_desc mchp_ac40t08a_desc = {
> >  	.init_sequence = mchp_ac40t08a_init_sequence,
> >  };
> > <snip>
> > +
> > +static const struct drm_display_mode hl055fhav028c_mode = {
> > +	.hdisplay	= 1080,
> > +	.hsync_start	= 1080 + 32,
> > +	.hsync_end	= 1080 + 32 + 8,
> > +	.htotal		= 1080 + 32 + 8 + 32,
> > +	.vdisplay	= 1920,
> > +	.vsync_start	= 1920 + 16,
> > +	.vsync_end	= 1920 + 16 + 2,
> > +	.vtotal		= 1920 + 16 + 2 + 14,
> 
> Shouldn't this be 's/14/16/' ?

Could you give a reason for why you think so please, so that we
don't dance around the perceived problem too long :-) .

The front-porch / back-porch values are not generally identical
that is more a random event.

Grabbing a random panel like the panel-leadtek-ltk050h3146w.c
you'll see the values not matching.

So those timing values are specific to the panel and in the common
case not identical.

Heiko

> 
> Cheers,
>   Diederik
> 
> > +	.clock		= 134920,
> > +	.flags		= DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
> > +	.width_mm	= 70,
> > +	.height_mm	= 127,
> > +};
> > +
> > +static const struct hx8394_panel_desc hl055fhav028c_desc = {
> > +	.mode = &hl055fhav028c_mode,
> > +	.lanes = 4,
> > +	.mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST,
> > +	.format = MIPI_DSI_FMT_RGB888,
> > +	.init_sequence = hl055fhav028c_init_sequence,
> > +};
> > +
> >  static int hx8394_enable(struct drm_panel *panel)
> >  {
> >  	struct hx8394 *ctx = panel_to_hx8394(panel);
> > @@ -683,6 +824,7 @@ static void hx8394_remove(struct mipi_dsi_device *dsi)
> >  
> >  static const struct of_device_id hx8394_of_match[] = {
> >  	{ .compatible = "hannstar,hsd060bhw4", .data = &hsd060bhw4_desc },
> > +	{ .compatible = "huiling,hl055fhav028c", .data = &hl055fhav028c_desc },
> >  	{ .compatible = "powkiddy,x55-panel", .data = &powkiddy_x55_desc },
> >  	{ .compatible = "microchip,ac40t08a-mipi-panel", .data = &mchp_ac40t08a_desc },
> >  	{ /* sentinel */ }
> 
> 

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