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Commit 10175601 authored by Martin Blumenstingl's avatar Martin Blumenstingl Committed by Neil Armstrong
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drm/meson: use unsigned long long / Hz for frequency types



Christian reports that 4K output using YUV420 encoding fails with the
following error:
  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 -------------------------------------^

This indicates that there's a (1kHz) mismatch between the clock
calculated by the drm framework and the meson driver.

Relevant function call stack:
(drm framework)
  -> meson_encoder_hdmi_atomic_enable()
    -> meson_encoder_hdmi_set_vclk()
      -> meson_vclk_setup()

The video clock requested by the drm framework is 593407kHz. This is
passed by meson_encoder_hdmi_atomic_enable() to
meson_encoder_hdmi_set_vclk() and the following formula is applied:
- the frequency is halved (which would be 296703.5kHz) and rounded down
  to the next full integer, which is 296703kHz
- TMDS clock is calculated (296703kHz * 10)
- video encoder clock is calculated - this needs to match a table from
  meson_vclk.c and so it doubles the previously halved value again
  (resulting in 593406kHz)
- meson_vclk_setup() can't find (either directly, or by deriving it from
  594000kHz * 1000 / 1001 and rounding to the closest integer value -
  which is 593407kHz as originally requested by the drm framework) a
  matching clock in it's internal table and errors out with "invalid
  HDMI vclk freq"

Fix the division precision by switching the whole meson driver to use
unsigned long long (64-bit) Hz values for clock frequencies instead of
unsigned int (32-bit) kHz to fix the rouding error.

Fixes: e5fab2ec ("drm/meson: vclk: add support for YUV420 setup")
Reported-by: default avatarChristian Hewitt <christianshewitt@gmail.com>
Signed-off-by: default avatarMartin Blumenstingl <martin.blumenstingl@googlemail.com>
Reviewed-by: default avatarNeil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20250421201300.778955-3-martin.blumenstingl@googlemail.com


Signed-off-by: default avatarNeil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20250421201300.778955-3-martin.blumenstingl@googlemail.com
parent f37bb548
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