topic lvds output to mipi input in i.MX Processors

lvds output to mipi input

yufe — Fri, 13 Oct 2017 07:47:51 GMT

hello all,

i have two imx6 custom board, first board use ldb output image, and second board receive image and send it to lcd.

first board second board

fb->ldb --(max9277/max9288)-> mipi->fb->lcd

first board's fb format is RGB565, mxc fb pixformat is also RGB565. Second board's mipi is set as RGB565, v4l2 capture format also RGB565.(max9277 and max9286 is maxim's Serializers and Deserializers, i config max9286 as RGB565). the lcd's output is not match:chrome component is not correct.

is there something wrong with my configuration?

if i can set mxc's pixformat as RGB565 ? it normally set as RGB24 or RGB666

if the ldb's SPWG standard not match csi mipi format?

Re: lvds output to mipi input

igorpadykov — Fri, 13 Oct 2017 23:26:43 GMT

Hi yu

ldb uses only 18 or 24 bits format as defined by

"data_width" bit register LDB_CTRL. It can not use 16 bits

(RGB565), so fb format RGB565 should be converted to 18 or 24 bit

formats, sent by ldb and converted back on second board. Please

check sect.37.4.2.3 FCW & FCR - Format converter i.MX6DQ Reference Manual

http://www.nxp.com/docs/en/reference-manual/IMX6DQRM.pdf

may be useful to check ipu examples

https://community.nxp.com/docs/DOC-94961

Best regards
igor
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Re: lvds output to mipi input

yufe — Sun, 15 Oct 2017 13:06:21 GMT

hi igorpadykov,

thanks for your replay.

that is to say i can not set mxc fb format as RTGB56, YUYV16 or some other formats, expect RGB666 or RGB24, when ldb bitwidth is 18?

in current linux ipu driver(3.14.52), ipu will do nothing when dataflow from fb to ldb when i set fb format as RGB565 and ldb bitwidth as 18?

Re: lvds output to mipi input

igorpadykov — Sun, 15 Oct 2017 23:02:48 GMT

Hi yu

> i can not set mxc fb format as RTGB56, YUYV16 or some other formats, expect RGB666 or RGB24, when ldb bitwidth is 18?

yes, when when ldb bitwidth is 18, fb format should be adjusted to RGB666

>ipu will do nothing when dataflow from fb to ldb when i set fb format as RGB565 and ldb bitwidth as 18?

right

Best regards
igor

Re: lvds output to mipi input

yufe — Mon, 16 Oct 2017 04:52:03 GMT

hi igorpadykov,

in current linux driver, i can only choose RGB565 as mxc fb's pixformat, so i can not use ipu to convert rgb format in user space.

is there a patch to support RGB565 to RGB666 conversion in mxc fb driver? i found it's too hard form me to modify ipu driver code. i think it's a common problem when someone choose ldb as output device.

Re: lvds output to mipi input

igorpadykov — Mon, 16 Oct 2017 06:02:34 GMT

Hi yu

>is there a patch to support RGB565 to RGB666 conversion in mxc fb driver?

I am afraid not, sorry. One can apply to NXP Professional Services to develop it:
http://www.nxp.com/support/nxp-professional-services:PROFESSIONAL-SERVICE

Best regards
igor