linux-yocto/drivers/gpu/drm/meson/meson_vclk.h
Martin Blumenstingl 1f8d03fb90 drm/meson: use unsigned long long / Hz for frequency types
[ Upstream commit 1017560164b6bbcbc93579266926e6e96675262a ]

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: e5fab2ec9c ("drm/meson: vclk: add support for YUV420 setup")
Reported-by: Christian Hewitt <christianshewitt@gmail.com>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20250421201300.778955-3-martin.blumenstingl@googlemail.com
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20250421201300.778955-3-martin.blumenstingl@googlemail.com
Stable-dep-of: d17e61ab63fb ("drm/meson: fix debug log statement when setting the HDMI clocks")
Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-06-19 15:28:40 +02:00

38 lines
950 B
C

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* Copyright (C) 2016 BayLibre, SAS
* Author: Neil Armstrong <narmstrong@baylibre.com>
*/
/* Video Clock */
#ifndef __MESON_VCLK_H
#define __MESON_VCLK_H
#include <drm/drm_modes.h>
struct meson_drm;
enum {
MESON_VCLK_TARGET_CVBS = 0,
MESON_VCLK_TARGET_HDMI = 1,
MESON_VCLK_TARGET_DMT = 2,
};
/* 27MHz is the CVBS Pixel Clock */
#define MESON_VCLK_CVBS (27 * 1000 * 1000)
enum drm_mode_status
meson_vclk_dmt_supported_freq(struct meson_drm *priv, unsigned long long freq);
enum drm_mode_status
meson_vclk_vic_supported_freq(struct meson_drm *priv,
unsigned long long phy_freq,
unsigned long long vclk_freq);
void meson_vclk_setup(struct meson_drm *priv, unsigned int target,
unsigned long long phy_freq, unsigned long long vclk_freq,
unsigned long long venc_freq, unsigned long long dac_freq,
bool hdmi_use_enci);
#endif /* __MESON_VCLK_H */