| Message ID | 1310589152-31945-1-git-send-email-ajax@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, 13 Jul 2011 16:32:32 -0400, Adam Jackson <ajax@redhat.com> wrote: > + if (width & 1) > + width++; > + if (height & 1) > + height++; You'll want to stick a comment in here describing why this is here. Otherwise, someone will just break it in the future.
On Wed, 2011-07-13 at 16:32 -0400, Adam Jackson wrote: > Consider a 1600x900 panel, upscaling a 1360x768 mode, full-aspect. The > old math would give you: > > scaled_width = 1600 * 768; /* 1228800 */ > scaled_height = 1360 * 900; /* 1224000 */ > if (scaled_width > scaled_height) { /* pillarbox, and true */ > width = 1224000 / 768; /* int(1593.75) = 1593 */ > x = (1600 - 1593 + 1) / 2; /* 4 */ > y = 0; > height = 768; > } /* ... */ > > This is broken. The total width of scanout would then be 1593 + 4 + 4, > or 1601, which is wider than the panel itself. The hardware very > dutifully implements this, and you end up with a black 45° diagonal from > the top-left corner to the bottom edge of the screen. It's a cool > effect and all, but not what you wanted. Similar things happen for the > letterbox case. > > The problem is that you have an integer number of pixels, which means > it's usually impossible to upscale equally on both axes. 1360/768 is > 1.7708, 1600/900 is 1.7777. Since we're constrained on the one axis, > the other one wants to come out as an even number of pixels (the panel > is almost certainly even on both axes, and the x/y offsets will be > applied on both sides). In the math above, if 'width' comes out even, > rounding down is correct; if it's odd, you'd rather round up. So just > increment width/height in those cases. > > Tested on a Lenovo T500 (Ironlake). > > Signed-off-by: Adam Jackson <ajax@redhat.com> > --- > drivers/gpu/drm/i915/intel_panel.c | 4 ++++ > 1 files changed, 4 insertions(+), 0 deletions(-) > > diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c > index a06ff07..05f500c 100644 > --- a/drivers/gpu/drm/i915/intel_panel.c > +++ b/drivers/gpu/drm/i915/intel_panel.c > @@ -83,11 +83,15 @@ intel_pch_panel_fitting(struct drm_device *dev, > u32 scaled_height = mode->hdisplay * adjusted_mode->vdisplay; > if (scaled_width > scaled_height) { /* pillar */ > width = scaled_height / mode->vdisplay; > + if (width & 1) > + width++; > x = (adjusted_mode->hdisplay - width + 1) / 2; > y = 0; > height = adjusted_mode->vdisplay; > } else if (scaled_width < scaled_height) { /* letter */ > height = scaled_width / mode->hdisplay; > + if (height & 1) > + height++; > y = (adjusted_mode->vdisplay - height + 1) / 2; > x = 0; > width = adjusted_mode->hdisplay; We've seen this in Ubuntu in the form of https://bugs.launchpad.net/ubuntu/+source/linux/+bug/753994 so we can add a Tested-By: Daniel Manrique <daniel.manrique@canonical.com>
On Wed, 13 Jul 2011 16:32:32 -0400, Adam Jackson <ajax@redhat.com> wrote: > Consider a 1600x900 panel, upscaling a 1360x768 mode, full-aspect. The > old math would give you: > > scaled_width = 1600 * 768; /* 1228800 */ > scaled_height = 1360 * 900; /* 1224000 */ > if (scaled_width > scaled_height) { /* pillarbox, and true */ > width = 1224000 / 768; /* int(1593.75) = 1593 */ > x = (1600 - 1593 + 1) / 2; /* 4 */ > y = 0; > height = 768; > } /* ... */ > > This is broken. The total width of scanout would then be 1593 + 4 + 4, > or 1601, which is wider than the panel itself. The hardware very > dutifully implements this, and you end up with a black 45° diagonal from > the top-left corner to the bottom edge of the screen. It's a cool > effect and all, but not what you wanted. Similar things happen for the > letterbox case. I'm going to show my ignorance but why did the hw apply the offset to both sides of the output and generate a new mode line? That's probably inherent in the nature of the hblanks, I guess? The entirety of the description I have is that the position is simply the origin of the top-left pixel of the fitted window. So a comment here is necessary, but otherwise: Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=38851 Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> And a big thank you. -Chris
diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c index a06ff07..05f500c 100644 --- a/drivers/gpu/drm/i915/intel_panel.c +++ b/drivers/gpu/drm/i915/intel_panel.c @@ -83,11 +83,15 @@ intel_pch_panel_fitting(struct drm_device *dev, u32 scaled_height = mode->hdisplay * adjusted_mode->vdisplay; if (scaled_width > scaled_height) { /* pillar */ width = scaled_height / mode->vdisplay; + if (width & 1) + width++; x = (adjusted_mode->hdisplay - width + 1) / 2; y = 0; height = adjusted_mode->vdisplay; } else if (scaled_width < scaled_height) { /* letter */ height = scaled_width / mode->hdisplay; + if (height & 1) + height++; y = (adjusted_mode->vdisplay - height + 1) / 2; x = 0; width = adjusted_mode->hdisplay;
Consider a 1600x900 panel, upscaling a 1360x768 mode, full-aspect. The old math would give you: scaled_width = 1600 * 768; /* 1228800 */ scaled_height = 1360 * 900; /* 1224000 */ if (scaled_width > scaled_height) { /* pillarbox, and true */ width = 1224000 / 768; /* int(1593.75) = 1593 */ x = (1600 - 1593 + 1) / 2; /* 4 */ y = 0; height = 768; } /* ... */ This is broken. The total width of scanout would then be 1593 + 4 + 4, or 1601, which is wider than the panel itself. The hardware very dutifully implements this, and you end up with a black 45° diagonal from the top-left corner to the bottom edge of the screen. It's a cool effect and all, but not what you wanted. Similar things happen for the letterbox case. The problem is that you have an integer number of pixels, which means it's usually impossible to upscale equally on both axes. 1360/768 is 1.7708, 1600/900 is 1.7777. Since we're constrained on the one axis, the other one wants to come out as an even number of pixels (the panel is almost certainly even on both axes, and the x/y offsets will be applied on both sides). In the math above, if 'width' comes out even, rounding down is correct; if it's odd, you'd rather round up. So just increment width/height in those cases. Tested on a Lenovo T500 (Ironlake). Signed-off-by: Adam Jackson <ajax@redhat.com> --- drivers/gpu/drm/i915/intel_panel.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-)