[Intel-gfx] [PATCH] drm/i915: Reudce CHV DPLL min vco frequency to 4.8 GHz

[Daniel Vetter]

On Wed, Mar 04, 2015 at 05:10:02PM +0200, Ville Syrjälä wrote:
> On Wed, Mar 04, 2015 at 08:11:38PM +0530, Purushothaman, Vijay A wrote:
> > On 2/27/2015 12:31 AM, ville.syrjala at linux.intel.com wrote:
> > > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > >
> > > The current minimum vco frequency leaves us with a gap in our supported
> > > frequencies at 233-243 MHz. Your typical 2560x1440 at 60 display wants a
> > > pixel clock of 241.5 MHz, which is just withing that gap. Reduce the
> > > allowed vco min frequency to 4.8GHz to reduce the gap to 233-240 MHz,
> > > and thus allow such displays to work.
> > >
> > > 4.8 GHz is actually the documented (at least in some docs) limit of the
> > > PLL, and we just picked 4.86 GHz originally because that was the lowest
> > > value produced by the PLL spreadsheet, which obviously didn't consider
> > > 2560x1440 displays.
> > >
> > > Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > > ---
> > >   drivers/gpu/drm/i915/intel_display.c | 2 +-
> > >   1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > > index 102b12d..d437a21 100644
> > > --- a/drivers/gpu/drm/i915/intel_display.c
> > > +++ b/drivers/gpu/drm/i915/intel_display.c
> > > @@ -390,7 +390,7 @@ static const intel_limit_t intel_limits_chv = {
> > >   	 * them would make no difference.
> > >   	 */
> > >   	.dot = { .min = 25000 * 5, .max = 540000 * 5},
> > > -	.vco = { .min = 4860000, .max = 6700000 },
> > > +	.vco = { .min = 4800000, .max = 6700000 },
> > >   	.n = { .min = 1, .max = 1 },
> > >   	.m1 = { .min = 2, .max = 2 },
> > >   	.m2 = { .min = 24 << 22, .max = 175 << 22 },
> > 
> > Minor nitpick: typo in patch title
> 
> Dang. I already fixed a typo there before sending this out, but turns
> out I only managed to cchange it into a different typo :( Maybe I need
> to invest in a spell checker...

Fixed and applied, thanks.
-Daniel

> 
> > 
> > Reviewed-by: Vijay Purushothaman <vijay.a.purushothaman at linux.intel.com>
> > 
> > Thanks,
> > Vijay
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx at lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> -- 
> Ville Syrjälä
> Intel OTC
> _______________________________________________
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> Intel-gfx at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch