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drm/rockchip: vop2: make vp registers nonvolatile

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Make video port registers nonvolatile. As DSP_CTRL register is written
to twice due to gamma LUT enable bit which is set outside of the main
DSP_CTRL initialization within atomic_enable (for rk356x case it is also
necessary to always disable gamma LUT before writing a new LUT) there is
a chance that DSP_CTRL value read-out in gamma LUT init/update code is
not the one which was written by the preceding DSP_CTRL initialization
code within atomic_enable. This might result in misconfigured DSP_CTRL
which leads to no visual output[1]. Since DSP_CTRL write takes effect
after VSYNC[1] the issue is not always present. When tested on Pinetab2
with kernel 6.14 it happenes only when DRM is compiled as a module[1].
In order to confirm that it is a timing issue I inserted 18ms udelay
before vop2_crtc_atomic_try_set_gamma in atomic enable and compiled DRM
as module - this has also fixed the issue.

[1] https://lore.kernel.org/linux-rockchip/562b38e5.a496.1975f09f983.Coremail.andyshrk@163.com/

Reported-by: Diederik de Haas <didi.debian@cknow.org>
Closes: https://lore.kernel.org/linux-rockchip/DAEVDSTMWI1E.J454VZN0R9MA@cknow.org/
Suggested-by: Andy Yan <andy.yan@rock-chips.com>
Signed-off-by: Piotr Zalewski <pZ010001011111@proton.me>
Tested-by: Diederik de Haas <didi.debian@cknow.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20250706083629.140332-2-pZ010001011111@proton.me
This commit is contained in:
Piotr Zalewski 2025-07-06 08:36:58 +00:00 committed by Heiko Stuebner
parent ea177a1b1e
commit a52dffaa46
1 changed files with 5 additions and 4 deletions
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9
drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
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@ -2579,12 +2579,13 @@ static int vop2_win_init(struct vop2 *vop2)
} }
/* /*
* The window registers are only updated when config done is written. * The window and video port registers are only updated when config
* Until that they read back the old value. As we read-modify-write * done is written. Until that they read back the old value. As we
* these registers mark them as non-volatile. This makes sure we read * read-modify-write these registers mark them as non-volatile. This
* the new values from the regmap register cache. * makes sure we read the new values from the regmap register cache.
*/ */
static const struct regmap_range vop2_nonvolatile_range[] = { static const struct regmap_range vop2_nonvolatile_range[] = {
regmap_reg_range(RK3568_VP0_CTRL_BASE, RK3588_VP3_CTRL_BASE + 255),
regmap_reg_range(0x1000, 0x23ff), regmap_reg_range(0x1000, 0x23ff),
}; };