Need some advice on LCD driver in Chrome u-boot

Stephen Warren swarren at nvidia.com
Sat Nov 19 03:14:33 EST 2011


AIUI, yes you'll need to rewrite the LCD driver, but this should just be a manual replacement of the bit-twiddling macros with manually coded manipulations.

I don't see much point upstreaming a .dts file that's completely untested; having it upstream before we're able to use it won't benefit us in any way, will it? Now, if we started initializing a bunch of stuff besides LCD from it, then it'd make sense.

Please make sure you have the LCD bindings (and whole .dts file) reviewed on devicetree-discuss at lists.ozlabs.org<mailto:devicetree-discuss at lists.ozlabs.org>, since that's the main .dts review list. The .dts needs to be co-ordinated with other users such as the Linux kernel.

_____________________________________________
From: Mayuresh Kulkarni
Sent: Thursday, November 17, 2011 11:27 PM
To: Uboot-dev
Cc: Pritesh Raithatha; Varun Wadekar
Subject: Need some advice on LCD driver in Chrome u-boot


Hi All,

I need advice on following points about up-streaming the LCD driver:

- Chrome's u-boot implementation uses special bit-fields macros to implement the core display driver (for register read/writes). You can check this implementation in u-boot/arch/arm/cpu/armv7/tegra2/display.c.
- As you might be aware, Pritesh is working on getting I2C driver up-stream which also uses bit-field macros in Chrome's u-boot. He has been given a comment that, this needs to be removed before up-streaming, as these macros are not accepted by Denx.
- As I understand, this means that the display driver needs to be rewritten to use standard readl/writel APIs. Is this correct understanding?
- If it needs to be rewritten, it is going to take some time. So is it OK if we push a reviewed copy of tegra2-ventana.dts (name could be decided upon) to Denx's master branch at this point of time? This commit will not be tested as there is no driver in master which would use this. Are such commits accepted?

In general, how are such issues handled by the u-boot community?

Mayuresh Kulkarni
NVIDIA Graphics Pvt Ltd




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