Re: mxsfb on i.MX28 uses bypassed ref_xtal 24MHz clock for LCD

From: Hector Palacios
Date: Mon May 20 2013 - 11:00:08 EST

Dear Fabio,

On 05/17/2013 04:07 PM, Fabio Estevam wrote:
On 05/17/2013 10:57 AM, Hector Palacios wrote:

On the MX28EVK board with the Seiko 4.3" LCD, I do not see the penguin
or any image in v3.8 or v3.9 though the framebuffer device is present
and correctly loaded and backlight on.
This LCD works in kernel v2.6.35 with the same 24MHz frequency.
@Fabio, does this LCD work out of the box on v3.9? Am I missing something?

Yes, works fine here.

Make sure you update both the kernel and dtb files on your tests.

Agh. Now it works on the EVK. I had something wrong with the backlight (maybe a bad DTB).

Do you have any comment on the fact that the lcdif clock is bypassed to the 24MHz ref clock? Doesn't this make useless the definition of pixelclk for the different displays in mach-mxs.c?
You can only obtain whole divisors of this frequency (24, 12, 6, 4), which may not be accurate enough to fit some displays.

Héctor Palacios
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