Messages in this thread | | | Date | Tue, 12 May 2009 14:30:03 +0200 | From | Nicolas Ferre <> | Subject | Re: atmel_lcdfb: max pixclock check |
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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/
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