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

[Diederik de Haas]

On Thu Jun 5, 2025 at 2:46 PM CEST, Heiko Stübner wrote:
> 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 at 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 at 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 :-) .

Yeah, sorry.
.htotal appears like the value from .hsync_end + .hsync_start (minus the
1080) and with that same logic, I would expect .vtotal to be .vsync_end
+ vsync_start (minus the 1920). So the '14' could've been a typo.

Hope that clarifies my thought process.

Cheers,
  Diederik

> 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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