lkml.org 
[lkml]   [2009]   [May]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: atmel_lcdfb: max pixclock check
Daniel Glöckner :
> Hi,
> in the current Atmel LCD framebuffer driver there is the following check in the
> fb_check_var callback:
>
> if ((PICOS2KHZ(var->pixclock) * var->bits_per_pixel / 8) > clk_value_khz) {
> dev_err(dev, "%lu KHz pixel clock is too fast\n",
> PICOS2KHZ(var->pixclock));
> return -EINVAL;
> }
>
> I can't find any constraint like this in the data sheets and application note.
> What I can find is a minimum for clk_value_khz/PICOS2KHZ(var->pixclock)
> depending on the display type, scan mode, and interface width.

Indeed, I have just acked a patch from Ben Nizette removing this constrain.
http://lkml.org/lkml/2009/5/12/189

> Is the quoted if-statement correct or should it be changed to a minimum clock
> divider check?

We can imagine such a check depending on display type. Patches welcome ;-)

> And while we're at it, is it correct to return -EINVAL here instead of changing
> var->pixclock to the closest supported value?

I do not know... Maybe someone on linux-fb-devel can answer ?

Bye,
--
Nicolas Ferre
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2009-05-12 14:33    [W:0.107 / U:0.084 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site