Re: [PATCH 1/2] dt-bindings: display: panel: add Ilitek ILI7807S panel controller

[Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>]

On Tue, May 26, 2026 at 04:02:45PM +0530, Arpit Saini wrote:
> Hi Krzysztof , Dmitry
> 
> On 5/20/2026 6:56 PM, Dmitry Baryshkov wrote:
> > On Wed, May 20, 2026 at 06:10:57PM +0530, Arpit Saini wrote:
> > > Hi Krzysztof , Dmitry
> > > 
> > > On 5/19/2026 4:02 PM, Krzysztof Kozlowski wrote:
> > > > On Mon, May 18, 2026 at 04:34:12PM +0530, Arpit Saini wrote:
> > > > > ILI7807S is a DSI display controller used to drive MIPI-DSI panels.
> > > > > The DLC DLC0697 1080x1920 LCD panel is based on this controller.
> > 
> > I can't find this panel on the DLC website. Do you have a pointer to the
> > product page?
> > 
> https://v4.cecdn.yun300.cn/100001_2012175013/DLC0697AAL21MF-1.pdf

"Invalid referrer"

> > > > > 
> > > > > The panel requires a reset GPIO, backlight enable GPIO, I/O voltage
> > > > 
> > > > If panel requires it, so should the binding.
> > > > 
> > > Ack, I will update.
> > > > ...
> > > > 
> > > > > +  reg:
> > > > > +    maxItems: 1
> > > > > +    description: DSI virtual channel
> > > > > +
> > > > > +  reset-gpios: true
> > > > > +
> > > > > +  backlight-en-gpios:
> > > > > +    description: Backlight enable GPIO (active high)
> > > > 
> > > > What is the name of the pin in ili7807s device?
> > > > 
> > > Display daughter card has WLED driver as well as LCD bias driver.
> > 
> > What is the display daughter card here? Is it a Qualcomm board or is it
> > a part of the panel?
> > 
> > Also you wrote a lot of text, but you didn't really answer either of the
> > quesitons. Is there a GPIO on the panel connector that enables the
> > backlight? If not, this is some external supply on your (assumingly)
> > daughter card. And it should be modelled accordingly.

Still unanswered.

> > 
> > > 
> > > The WLED driver's Enable is coming from WLED_P1_EN and PWM is coming from
> > > LCD_CABC output of the panel.
> > > 
> > > DISPLAY0_BACKLIGHT_ENABLE (GPIO 91) of ITP baseband card ==> WLED_P1_EN of
> > > Display Daughter Card (DC)
> > > 
> > > In the display daughter card of Shikra ITP platform, we are not using the
> > > external PWM for WLED driver. But connected the CABC output of the panel to
> > > the WLED driver. Backlight update is happening using MIPI DCS command which
> > > is driving the CABC output (i.e., PWM for WLED).
> > > 
> > > Because of above HW configuration, we need to enable the MIPI DCS brightness
> > > update on this panel. The below command of dlc0697_init_sequence() is
> > > enabling this.
> > > mipi_dsi_dcs_write_seq_multi(dsi_ctx, 0x53, 0x24);
> > 
> > So, this should be then dependent on the presence of the backlight in
> > the DT. Either it is a panel-internal one, or an external one.
> > 
> > > 
> > > 
> > > After checking this, I realized that this panel can be used without the DCS
> > > backlight as well when it's using PWM based backlight control.
> > > 
> > > I can add `has_dcs_backlight`  in panel_desc and set it true for dlc0697. I
> > > will update bindings and add backlight as optional property.
> > 
> > Why? Use backlight property instead. It's already there. Anyway, you
> > really, really need to describe the panel in the bidings. Not your
> > daughter card.
> > 
> This `has_dcs_backlight` in panel_desc will serves both the purpose, as for
> our current platform constraint , we need to create our own backlight.
> But this panel can be used without the DCS
> backlight as well when it's using PWM based backlight control.
> 
> So in this case I need to implement the backlight as implemented in
> panel-novatek-nt36523.c, panel-himax-hx83121a.c.
> 
> with this implementation ,I will remove the backlight from the dt-bindings.

Much easier. Call drm_panel_of_backlight() and if there is no error and
panel->backlight is still NULL, then create your own backlight device.

> 
> Please let me know,if I am missing something.
> 
> Thanks,
> Arpit
> 
> 

-- 
With best wishes
Dmitry