lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Fri, 3 Jun 2022 10:24:16 +0200 From: Maxime Ripard <maxime@...no.tech> To: Roman Stratiienko <r.stratiienko@...il.com> Cc: wens@...e.org, jernej.skrabec@...il.com, airlied@...ux.ie, daniel@...ll.ch, samuel@...lland.org, dri-devel@...ts.freedesktop.org, linux-arm-kernel@...ts.infradead.org, linux-sunxi@...ts.linux.dev, linux-kernel@...r.kernel.org, megi@....cz Subject: Re: [PATCH] drm/sun4i: sun8i: Add the ability to keep scaler enabled for VI layer Hi, On Thu, Jun 02, 2022 at 06:01:18PM +0000, Roman Stratiienko wrote: > According to DE2.0/DE3.0 manual VI scaler enable register is double > buffered, but de facto it doesn't, or the hardware has the shadow > register latching issues which causes single-frame picture corruption > after changing the state of scaler enable register. > > Allow the user to keep the scaler always enabled, preventing the UI > glitches on the transition from scaled to unscaled state. > > NOTE: > UI layer scaler has more registers with double-buffering issue and can't > be workarounded in the same manner. > > You may find a python test and a demo video for this issue at [1] > > [1]: https://github.com/GloDroid/glodroid_tests/issues/4 Please describe the issue entirely here. The commit log must be self-sufficient. > Signed-off-by: Roman Stratiienko <r.stratiienko@...il.com> > --- > drivers/gpu/drm/sun4i/sun8i_mixer.c | 12 ++++++++++++ > drivers/gpu/drm/sun4i/sun8i_vi_layer.c | 4 +++- > 2 files changed, 15 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/sun4i/sun8i_mixer.c b/drivers/gpu/drm/sun4i/sun8i_mixer.c > index 71ab0a00b4de..15cad0330f66 100644 > --- a/drivers/gpu/drm/sun4i/sun8i_mixer.c > +++ b/drivers/gpu/drm/sun4i/sun8i_mixer.c > @@ -27,6 +27,18 @@ > #include "sun8i_vi_layer.h" > #include "sunxi_engine.h" > > +/* According to DE2.0/DE3.0 manual VI scaler enable register is double > + * buffered, but de facto it doesn't, or the hardware has the shadow > + * register latching issues which causes single-frame picture corruption > + * after changing the state of scaler enable register. > + * Allow the user to keep the scaler always enabled, preventing the UI > + * glitches on the transition from scaled to unscaled state. > + */ > +int sun8i_vi_keep_scaler_enabled; > +MODULE_PARM_DESC(keep_vi_scaler_enabled, > + "Keep VI scaler enabled (1 = enabled, 0 = disabled (default))"); > +module_param_named(keep_vi_scaler_enabled, sun8i_vi_keep_scaler_enabled, int, 0644); > + It's not clear to me why we would want to make that a parameter? If it never works, we should fix it once and for all and not allow a broken setup at all. Maxime
Powered by blists - more mailing lists