Re: [PATCH 14/16] soc: imx: gpcv2: move reset assert after requesting domain power up

[Peng Fan (OSS)]

On 2021/4/29 22:28, Lucas Stach wrote:
> Am Donnerstag, dem 29.04.2021 um 15:30 +0800 schrieb Peng Fan (OSS):
> > From: Peng Fan <peng.fan@xxxxxxx>
> >
> > The i.MX8MM VPU power up sequence is a bit special, it must follow:
> > 1. request power up
> > 2. reset assert
> > 3. reset deassert
> >
> > This change in this patch will not affect other domains, because
> > the power domain default is in asserted state, unless bootloader
> > deassert the reset.
> >
> > [Note: We expect bootloader leave the domain in asserted state,
> > but this may not always be true, so we might need another solution
> > to address the VPU domain requirements]
>
> This is only about the VPU and GPU domain, where we need to handle the
> SRC reset from the GPC driver right?

For GPU, I have not tried. From current ATF implementation, I think yes.

 In that case I think it's a sane
> assumption that the bootloader does not touch those resets.
>
> > Signed-off-by: Peng Fan <peng.fan@xxxxxxx>
> > ---
> >   drivers/soc/imx/gpcv2.c | 4 ++--
> >   1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/soc/imx/gpcv2.c b/drivers/soc/imx/gpcv2.c
> > index d2ce47a5ebad..072f519462a5 100644
> > --- a/drivers/soc/imx/gpcv2.c
> > +++ b/drivers/soc/imx/gpcv2.c
> > @@ -217,8 +217,6 @@ static int imx_pgc_power_up(struct generic_pm_domain *genpd)
> >   		goto out_regulator_disable;
> >   	}
> >   
> >
> >
> >
> >
> >
> >
> >
> > -	reset_control_assert(domain->reset);
> > -
> >   	if (domain->bits.pxx) {
> >   		/* request the domain to power up */
> >   		regmap_update_bits(domain->regmap, GPC_PU_PGC_SW_PUP_REQ,
> > @@ -241,6 +239,8 @@ static int imx_pgc_power_up(struct generic_pm_domain *genpd)
> >   				   GPC_PGC_CTRL_PCR, 0);
> >   	}
> >   
> >
> >
> >
> >
> >
> >
> >
> > +	reset_control_assert(domain->reset);
> > +
> >   	/* delay for reset to propagate */
> >   	udelay(5);
>
> As this is a pretty arbitrary delay added by me, can you please check
> with the HW team or whoever knows, if this is sufficiently long for
> both GPU and VPU domains?

For VPU, from my test, it is enough. For GPU, ATF code use 10us, let me
try to enable GPU and do some test, I think 5us is long enough here.

Thanks,
Peng.

> Regards,
> Lucas