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    Subject[RESEND PATCH v6 18/27] drm/bridge: analogix_dp: Reorder plat_data->power_off to happen sooner
    Date
    From: Douglas Anderson <dianders@chromium.org>

    The current user of the analogix power_off is "analogix_dp-rockchip".
    That driver does this:
    - deactivate PSR
    - turn off a clock

    Both of these things (especially deactive PSR) should be done before
    we turn the PHY power off and turn off analog power. Let's move the
    callback up.

    Note that without this patch (and with
    https://patchwork.kernel.org/patch/9553349/ [seanpaul: this patch was
    not applied, but it seems like the race can still occur]), I experienced
    an error in reboot testing where one thread was at:

    rockchip_drm_psr_deactivate
    rockchip_dp_powerdown
    analogix_dp_bridge_disable
    drm_bridge_disable

    ...and the other thread was at:

    analogix_dp_send_psr_spd
    analogix_dp_enable_psr
    analogix_dp_psr_set
    psr_flush_handler

    The flush handler thread was finding AUX channel errors and eventually
    reported "Failed to apply PSR", where I had a kgdb breakpoint. Presumably
    the device would have eventually given up and shut down anyway, but it
    seems better to fix the order to be more correct.

    Cc: Kristian H. Kristensen <hoegsberg@chromium.org>
    Signed-off-by: Douglas Anderson <dianders@chromium.org>
    Signed-off-by: Sean Paul <seanpaul@chromium.org>
    Signed-off-by: Thierry Escande <thierry.escande@collabora.com>
    Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
    Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
    Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
    Reviewed-by: Archit Taneja <architt@codeaurora.org>
    ---

    drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 5 +++--
    1 file changed, 3 insertions(+), 2 deletions(-)

    diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
    index 69b2c16e5776..a260de4f0bd8 100644
    --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
    +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
    @@ -1337,12 +1337,13 @@ static void analogix_dp_bridge_disable(struct drm_bridge *bridge)
    }

    disable_irq(dp->irq);
    - analogix_dp_set_analog_power_down(dp, POWER_ALL, 1);
    - phy_power_off(dp->phy);

    if (dp->plat_data->power_off)
    dp->plat_data->power_off(dp->plat_data);

    + analogix_dp_set_analog_power_down(dp, POWER_ALL, 1);
    + phy_power_off(dp->phy);
    +
    clk_disable_unprepare(dp->clock);

    pm_runtime_put_sync(dp->dev);
    --
    2.17.0
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