| Message ID | 20170815234722.20700-2-eric@anholt.net (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 16.08.2017 01:47, Eric Anholt wrote: > The incoming mode might have a missing vrefresh field if it came from > drmModeSetCrtc(), which the kernel is supposed to calculate using > drm_mode_vrefresh(). We could either use that or the adjusted_mode's > original vrefresh value. > > However, we can maintain a more exact vrefresh value (not just the > integer approximation), by scaling by the ratio of our clocks. > > v2: Use math suggested by Andrzej Hajda instead. > v3: Simplify math now that adjusted_mode->clock isn't padded. > > Signed-off-by: Eric Anholt <eric@anholt.net> > --- > drivers/gpu/drm/vc4/vc4_dsi.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/vc4/vc4_dsi.c b/drivers/gpu/drm/vc4/vc4_dsi.c > index eb787eed8abe..2516cd3a1d87 100644 > --- a/drivers/gpu/drm/vc4/vc4_dsi.c > +++ b/drivers/gpu/drm/vc4/vc4_dsi.c > @@ -862,7 +862,8 @@ static bool vc4_dsi_encoder_mode_fixup(struct drm_encoder *encoder, > adjusted_mode->clock = pixel_clock_hz / 1000; > > /* Given the new pixel clock, adjust HFP to keep vrefresh the same. */ > - adjusted_mode->htotal = pixel_clock_hz / (mode->vrefresh * mode->vtotal); > + adjusted_mode->htotal = (adjusted_mode->clock * mode->htotal / > + mode->clock); Parentheses can be removed. Beside this: Reviewed-by: Andrzej Hajda <a.hajda@samsung.com> -- Regards Andrzej > adjusted_mode->hsync_end += adjusted_mode->htotal - mode->htotal; > adjusted_mode->hsync_start += adjusted_mode->htotal - mode->htotal; >
On Tue, 15 Aug 2017 16:47:19 -0700 Eric Anholt <eric@anholt.net> wrote: > The incoming mode might have a missing vrefresh field if it came from > drmModeSetCrtc(), which the kernel is supposed to calculate using > drm_mode_vrefresh(). We could either use that or the adjusted_mode's > original vrefresh value. > > However, we can maintain a more exact vrefresh value (not just the > integer approximation), by scaling by the ratio of our clocks. > > v2: Use math suggested by Andrzej Hajda instead. > v3: Simplify math now that adjusted_mode->clock isn't padded. > > Signed-off-by: Eric Anholt <eric@anholt.net> Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com> > --- > drivers/gpu/drm/vc4/vc4_dsi.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/vc4/vc4_dsi.c b/drivers/gpu/drm/vc4/vc4_dsi.c > index eb787eed8abe..2516cd3a1d87 100644 > --- a/drivers/gpu/drm/vc4/vc4_dsi.c > +++ b/drivers/gpu/drm/vc4/vc4_dsi.c > @@ -862,7 +862,8 @@ static bool vc4_dsi_encoder_mode_fixup(struct drm_encoder *encoder, > adjusted_mode->clock = pixel_clock_hz / 1000; > > /* Given the new pixel clock, adjust HFP to keep vrefresh the same. */ > - adjusted_mode->htotal = pixel_clock_hz / (mode->vrefresh * mode->vtotal); > + adjusted_mode->htotal = (adjusted_mode->clock * mode->htotal / > + mode->clock); > adjusted_mode->hsync_end += adjusted_mode->htotal - mode->htotal; > adjusted_mode->hsync_start += adjusted_mode->htotal - mode->htotal; >
diff --git a/drivers/gpu/drm/vc4/vc4_dsi.c b/drivers/gpu/drm/vc4/vc4_dsi.c index eb787eed8abe..2516cd3a1d87 100644 --- a/drivers/gpu/drm/vc4/vc4_dsi.c +++ b/drivers/gpu/drm/vc4/vc4_dsi.c @@ -862,7 +862,8 @@ static bool vc4_dsi_encoder_mode_fixup(struct drm_encoder *encoder, adjusted_mode->clock = pixel_clock_hz / 1000; /* Given the new pixel clock, adjust HFP to keep vrefresh the same. */ - adjusted_mode->htotal = pixel_clock_hz / (mode->vrefresh * mode->vtotal); + adjusted_mode->htotal = (adjusted_mode->clock * mode->htotal / + mode->clock); adjusted_mode->hsync_end += adjusted_mode->htotal - mode->htotal; adjusted_mode->hsync_start += adjusted_mode->htotal - mode->htotal;
The incoming mode might have a missing vrefresh field if it came from drmModeSetCrtc(), which the kernel is supposed to calculate using drm_mode_vrefresh(). We could either use that or the adjusted_mode's original vrefresh value. However, we can maintain a more exact vrefresh value (not just the integer approximation), by scaling by the ratio of our clocks. v2: Use math suggested by Andrzej Hajda instead. v3: Simplify math now that adjusted_mode->clock isn't padded. Signed-off-by: Eric Anholt <eric@anholt.net> --- drivers/gpu/drm/vc4/vc4_dsi.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)