Re: [PATCH v5 24/36] drm/bridge: analogix_dp: Reorder plat_data->power_off to happen sooner

Archit Taneja
2018-03-14T06:50:09Z

On Saturday 10 March 2018 03:53 AM, Enric Balletbo i Serra wrote:
> 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.
>

Reviewed-by: Archit Taneja <architt@codeaurora.org>

Thanks,
Archit

> 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>
> ---
>
> 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 37b16643f14c..eaf93cbd47a8 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);
>