Dts registration for fb and display timing - at91sam9g35

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sathya02
Posts: 5
Joined: Sat Jun 13, 2015 2:16 pm

Dts registration for fb and display timing - at91sam9g35

Sat Jun 13, 2015 2:52 pm

Hai,
I am working in Linux-3.18 (Yocto build system) for the board at91sam9g35. Am unable to get fb0 dev file. Is there any device tree registration for fb0, display timings. if any, Can you share the code. I have enabled fb driver in kernel"AT91/AT32 LCD Controller support"

I tried registering similar to at91sam9rl but failed to get /dev/fb0
sathya02
Posts: 5
Joined: Sat Jun 13, 2015 2:16 pm

Re: framebuffer registration for at91sam9g35 board in dtsi

Mon Jun 15, 2015 6:50 am

Can any one share the fb registration for at91samg35 board in dtsi file?
blue_z
Location: USA
Posts: 1550
Joined: Thu Apr 19, 2007 10:15 pm

Re: Dts registration for fb and display timing - at91sam9g35

Tue Jun 16, 2015 12:12 am

sathya02 wrote:I am working in Linux-3.18 (Yocto build system) for the board at91sam9g35.
The AT91SAM9G35 is a SoC, and not the name of a board.
So what board are you using?
sathya02 wrote:I have enabled fb driver in kernel"AT91/AT32 LCD Controller support"
That is not the correct driver for the LCD controller in the G35.
The driver previously known as drivers/video/atmel_hldcfb.c in version 3.10-at91 has been implemented in Linux version 3.18-at91 (but 4.0 for mainline) at drivers/gpu/drm/atmel_hlcdc/.
Any specifications in the Device Tree are irrelevant/ignored when the device driver is not built.

Regards
sathya02
Posts: 5
Joined: Sat Jun 13, 2015 2:16 pm

Re: Dts registration for fb and display timing - at91sam9g35

Tue Jun 16, 2015 7:13 am

blue_z, Thanks for the reply

dmesg logs, What does it means? What am missing?

I have initialsed tft, still not getting lcd.

[ 0.710937] platform atmel-hlcdc-dc: Driver atmel-hlcdc-display-controller requests probe deferral
[ 1.718750] atmel-hlcdc-display-controller atmel-hlcdc-dc: DRM device successfully registered

"[ 5.734375] atmel-hlcdc-display-controller atmel-hlcdc-dc: No connectors reported connected with modes"

[ 5.843750] atmel-hlcdc-display-controller atmel-hlcdc-dc: fb0: frame buffer device
[ 5.851562] atmel-hlcdc-display-controller atmel-hlcdc-dc: registered panic notifier

and

[ 0.640625] [drm] Initialized drm 1.1.0 20060810
[ 1.687500] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
[ 1.695312] [drm] No driver support for vblank timestamp query.
[ 5.718750] [drm] Cannot find any crtc or sizes - going 1024x768

where should i register my lcd panel information in device tree? and how?
hsync,vsync,bpp,.....
blue_z
Location: USA
Posts: 1550
Joined: Thu Apr 19, 2007 10:15 pm

Re: Dts registration for fb and display timing - at91sam9g35

Tue Jun 16, 2015 9:33 pm

sathya02 wrote:What am missing?
An answer to my question, what board are you using?
sathya02 wrote:where should i register my lcd panel information in device tree? and how?
What Device Tree files are you using?
What examples have you looked at?
I really don't know.

Regards
sathya02
Posts: 5
Joined: Sat Jun 13, 2015 2:16 pm

Re: Dts registration for fb and display timing - at91sam9g35

Wed Jun 17, 2015 6:02 am

Hai blue_z,

Am working in custom device, duplication of at91sam9x5ek and at91sam9g35 SOC.

Devicetree files are

at91sam9x35.dtsi,
at91sam9x5_lcd.dtsi,
at91sam9x5dm.dtsi,
at91sam9x35ek.dts.

And my lcd pin configuration is rgb565 and 320x480,

i modified rgb pin config in at91sam9x5dm.dtsi

"
hlcdc: hlcdc@f8038000 {
hlcdc-display-controller {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_lcd_rgb565>;"

and also

"atmel_hlcdc_dc.c"

atmel_hlcdc_dc_at91sam9x5 = {
.
.
.max_width = 320,
.max_height =480,
}

What i want is to initialise display. By default it is taking 1024x768 resolution, checked with fbset command.So where i need to register my lcd panel information to initialize display(320x480).


Thank you.
sathya02
Posts: 5
Joined: Sat Jun 13, 2015 2:16 pm

Re: Dts registration for fb and display timing - at91sam9g35

Wed Jun 17, 2015 7:41 am

christinalorence,

Am entirely new to Linux-3.18, looking for some clues to bring up my LCD display. So many device tree files confused with that. I have posted information not an essay.

Thank for your support.
nferre
Site Admin
Posts: 166
Joined: Wed Feb 14, 2007 11:17 am

Re: Dts registration for fb and display timing - at91sam9g35

Tue Aug 25, 2015 6:34 pm

Panel definitions are stored in C structures and linked from DT to the simple panel driver.

So, you can store your panel definition here: drivers/gpu/drm/panel/panel-simple.c and adapt your board DT accordingly.

Best regards,

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