[PATCH v3] soc: imx: gpcv2: Assert reset before ungating clock

[Lucas Stach]

Am Freitag, dem 12.08.2022 um 19:08 +0200 schrieb Marek Vasut:
> In case the power domain clock are ungated before the reset is asserted,
> the system might freeze completely. This is likely due to a device is an
> undefined state being attached to bus, which sporadically leads to a bus
> hang. Assert the reset before the clock are enabled to assure the device
> is in defined state before being attached to bus.
> 
> Fixes: fe58c887fb8ca ("soc: imx: gpcv2: add support for optional resets")
> Signed-off-by: Marek Vasut <marex at denx.de>

Reviewed-by: Lucas Stach <l.stach at pengutronix.de>

> ---
> Cc: Fabio Estevam <festevam 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>
> To: linux-arm-kernel at lists.infradead.org
> ---
> V2: - Always assert the reset before enabling clock
>     - Update commit message
>     - Add Fixes tag
> V3: Move the extra delay past clk_prepare_enable()
> ---
>  drivers/soc/imx/gpcv2.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/soc/imx/gpcv2.c b/drivers/soc/imx/gpcv2.c
> index 6383a4edc3607..88aee59730e39 100644
> --- a/drivers/soc/imx/gpcv2.c
> +++ b/drivers/soc/imx/gpcv2.c
> @@ -335,6 +335,8 @@ static int imx_pgc_power_up(struct generic_pm_domain *genpd)
>  		}
>  	}
>  
> +	reset_control_assert(domain->reset);
> +
>  	/* Enable reset clocks for all devices in the domain */
>  	ret = clk_bulk_prepare_enable(domain->num_clks, domain->clks);
>  	if (ret) {
> @@ -342,7 +344,8 @@ static int imx_pgc_power_up(struct generic_pm_domain *genpd)
>  		goto out_regulator_disable;
>  	}
>  
> -	reset_control_assert(domain->reset);
> +	/* delays for reset to propagate */
> +	udelay(5);
>  
>  	if (domain->bits.pxx) {
>  		/* request the domain to power up */