Messages in this thread | | | Date | Fri, 29 Mar 2024 16:59:50 +0100 | From | Neil Armstrong <> | Subject | Re: [PATCH] drm/meson: vclk: fix calculation of 59.94 fractional rates |
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On 10/01/2024 00:07, Christian Hewitt wrote: > Playing 4K media with 59.94 fractional rate (typically VP9) causes the screen to lose > sync with the following error reported in the system log: > > [ 89.610280] Fatal Error, invalid HDMI vclk freq 593406 > > Modetest shows the following: > > 3840x2160 59.94 3840 4016 4104 4400 2160 2168 2178 2250 593407 flags: xxxx, xxxx, > drm calculated value -------------------------------------^ > > Change the fractional rate calculation to stop DIV_ROUND_CLOSEST rounding down which > results in vclk freq failing to match correctly. > > Fixes: e5fab2ec9ca4 ("drm/meson: vclk: add support for YUV420 setup") > Signed-off-by: Christian Hewitt <christianshewitt@gmail.com> > --- > I'm unable to give a better mathematical description of the fix as I can barely read > code. The change was inspired by [0] which I chanced upon while looking at how other > dw-hdmi drivers handle fractional rates. > > [0] https://github.com/torvalds/linux/commit/4f510aa10468954b1da4e94689c38ac6ea8d3627 > > drivers/gpu/drm/meson/meson_vclk.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/meson/meson_vclk.c b/drivers/gpu/drm/meson/meson_vclk.c > index 2a82119eb58e..2a942dc6a6dc 100644 > --- a/drivers/gpu/drm/meson/meson_vclk.c > +++ b/drivers/gpu/drm/meson/meson_vclk.c > @@ -790,13 +790,13 @@ meson_vclk_vic_supported_freq(struct meson_drm *priv, unsigned int phy_freq, > FREQ_1000_1001(params[i].pixel_freq)); > DRM_DEBUG_DRIVER("i = %d phy_freq = %d alt = %d\n", > i, params[i].phy_freq, > - FREQ_1000_1001(params[i].phy_freq/10)*10); > + FREQ_1000_1001(params[i].phy_freq/1000)*1000); > /* Match strict frequency */ > if (phy_freq == params[i].phy_freq && > vclk_freq == params[i].vclk_freq) > return MODE_OK; > /* Match 1000/1001 variant */ > - if (phy_freq == (FREQ_1000_1001(params[i].phy_freq/10)*10) && > + if (phy_freq == (FREQ_1000_1001(params[i].phy_freq/1000)*1000) && > vclk_freq == FREQ_1000_1001(params[i].vclk_freq)) > return MODE_OK; > } > @@ -1070,7 +1070,7 @@ void meson_vclk_setup(struct meson_drm *priv, unsigned int target, > > for (freq = 0 ; params[freq].pixel_freq ; ++freq) { > if ((phy_freq == params[freq].phy_freq || > - phy_freq == FREQ_1000_1001(params[freq].phy_freq/10)*10) && > + phy_freq == FREQ_1000_1001(params[freq].phy_freq/1000)*1000) && > (vclk_freq == params[freq].vclk_freq || > vclk_freq == FREQ_1000_1001(params[freq].vclk_freq))) { > if (vclk_freq != params[freq].vclk_freq)
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
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