lkml.org 
[lkml]   [2022]   [Jun]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 5.18 329/339] drm/atomic: Force bridge self-refresh-exit on CRTC switch
    Date
    From: Brian Norris <briannorris@chromium.org>

    commit e54a4424925a27ed94dff046db3ce5caf4b1e748 upstream.

    It's possible to change which CRTC is in use for a given
    connector/encoder/bridge while we're in self-refresh without fully
    disabling the connector/encoder/bridge along the way. This can confuse
    the bridge encoder/bridge, because
    (a) it needs to track the SR state (trying to perform "active"
    operations while the panel is still in SR can be Bad(TM)); and
    (b) it tracks the SR state via the CRTC state (and after the switch, the
    previous SR state is lost).

    Thus, we need to either somehow carry the self-refresh state over to the
    new CRTC, or else force an encoder/bridge self-refresh transition during
    such a switch.

    I choose the latter, so we disable the encoder (and exit PSR) before
    attaching it to the new CRTC (where we can continue to assume a clean
    (non-self-refresh) state).

    This fixes PSR issues seen on Rockchip RK3399 systems with
    drivers/gpu/drm/bridge/analogix/analogix_dp_core.c.

    Change in v2:

    - Drop "->enable" condition; this could possibly be "->active" to
    reflect the intended hardware state, but it also is a little
    over-specific. We want to make a transition through "disabled" any
    time we're exiting PSR at the same time as a CRTC switch.
    (Thanks Liu Ying)

    Cc: Liu Ying <victor.liu@oss.nxp.com>
    Cc: <stable@vger.kernel.org>
    Fixes: 1452c25b0e60 ("drm: Add helpers to kick off self refresh mode in drivers")
    Signed-off-by: Brian Norris <briannorris@chromium.org>
    Reviewed-by: Sean Paul <seanpaul@chromium.org>
    Signed-off-by: Douglas Anderson <dianders@chromium.org>
    Link: https://patchwork.freedesktop.org/patch/msgid/20220228122522.v2.2.Ic15a2ef69c540aee8732703103e2cff51fb9c399@changeid
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    drivers/gpu/drm/drm_atomic_helper.c | 16 +++++++++++++---
    1 file changed, 13 insertions(+), 3 deletions(-)

    --- a/drivers/gpu/drm/drm_atomic_helper.c
    +++ b/drivers/gpu/drm/drm_atomic_helper.c
    @@ -1011,9 +1011,19 @@ crtc_needs_disable(struct drm_crtc_state
    return drm_atomic_crtc_effectively_active(old_state);

    /*
    - * We need to run through the crtc_funcs->disable() function if the CRTC
    - * is currently on, if it's transitioning to self refresh mode, or if
    - * it's in self refresh mode and needs to be fully disabled.
    + * We need to disable bridge(s) and CRTC if we're transitioning out of
    + * self-refresh and changing CRTCs at the same time, because the
    + * bridge tracks self-refresh status via CRTC state.
    + */
    + if (old_state->self_refresh_active &&
    + old_state->crtc != new_state->crtc)
    + return true;
    +
    + /*
    + * We also need to run through the crtc_funcs->disable() function if
    + * the CRTC is currently on, if it's transitioning to self refresh
    + * mode, or if it's in self refresh mode and needs to be fully
    + * disabled.
    */
    return old_state->active ||
    (old_state->self_refresh_active && !new_state->active) ||

    \
     
     \ /
      Last update: 2022-06-13 16:12    [W:2.486 / U:0.080 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site