[PATCH] soc: imx: gpcv2: Synchronously suspend MIX domains

[Lucas Stach]

Am Samstag, dem 16.10.2021 um 23:05 +0200 schrieb Marek Vasut:
> In case the following power domain sequence happens, iMX8M Mini always hangs:
>   gpumix:on -> gpu:on -> gpu:off -> gpu:on
> This is likely due to another quirk of the GPC block. This situation can be
> prevented by always synchronously powering off both the domain and MIX domain.
> Make it so. This turns the aforementioned sequence into:
>   gpumix:on -> gpu:on -> gpu:off -> gpumix:off -> gpumix:on -> gpu:on
> 
Did you test this with the reset sequence fixed? 2b2f106eb552 (Revert
"soc: imx: gpcv2: move reset assert after requesting domain power up")
in Shawns tree.

I don't like that this is slowing down the power-down sequence and I'm
not sure if it's required for the other domains, or if this is again a
GPU domain specific issue. However, if it's fixing a hang that isn't
solved by the proper reset sequence, I would say better safe than
sorry, and we can always optimize this later if possible.

Under the assumption that it's required even with the proper reset
sequence:
Acked-by: Lucas Stach <l.stach at pengutronix.de>

> Signed-off-by: Marek Vasut <marex at denx.de>
> Cc: Frieder Schrempf <frieder.schrempf at kontron.de>
> Cc: Lucas Stach <l.stach at pengutronix.de>
> Cc: NXP Linux Team <linux-imx at nxp.com>
> Cc: Peng Fan <peng.fan at nxp.com>
> Cc: Shawn Guo <shawnguo at kernel.org>
> ---
>  drivers/soc/imx/gpcv2.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/soc/imx/gpcv2.c b/drivers/soc/imx/gpcv2.c
> index b8d52d8d29db..e757044ab751 100644
> --- a/drivers/soc/imx/gpcv2.c
> +++ b/drivers/soc/imx/gpcv2.c
> @@ -377,7 +377,7 @@ static int imx_pgc_power_down(struct generic_pm_domain *genpd)
>  		}
>  	}
>  
> -	pm_runtime_put(domain->dev);
> +	pm_runtime_put_sync_suspend(domain->dev);
>  
>  	return 0;
>