Re: [PATCH v1 2/2] rockchip: power-domain: support qos save and restore

[Elaine Zhang]

hi, Heiko:

Thanks for your replay.
For your questions, I also have the same concerns.

On 04/02/2016 12:19 AM, Heiko Stuebner wrote:
> Hi Elaine,
>
> Am Freitag, 1. April 2016, 10:33:45 schrieb Elaine Zhang:
> > I agree with most of your modifications.
> > Except, the u32 *qos_save_regs below
>
> you're right. I didn't take that into account when my open-coding my idea.
> A bit more below:
>
> > On 04/01/2016 12:31 AM, Heiko Stuebner wrote:
> > > Hi Elaine,
> > >
> > > Am Freitag, 18. März 2016, 15:17:24 schrieb Elaine Zhang:
> > > > support qos save and restore when power domain on/off.
> > > >
> > > > Signed-off-by: Elaine Zhang <zhangqing@xxxxxxxxxxxxxx>
> > >
> > > overall looks nice already ... some implementation-specific comments
> > > below.>
> > > > ---
> > > >
> > > >    drivers/soc/rockchip/pm_domains.c | 87
> > > >
> > > > +++++++++++++++++++++++++++++++++++++-- 1 file changed, 84
> > > > insertions(+),
> > > > 3 deletions(-)
> > > >
> > > > diff --git a/drivers/soc/rockchip/pm_domains.c
> > > > b/drivers/soc/rockchip/pm_domains.c index 18aee6b..c5f4be6 100644
> > > > --- a/drivers/soc/rockchip/pm_domains.c
> > > > +++ b/drivers/soc/rockchip/pm_domains.c
> > > > @@ -45,10 +45,21 @@ struct rockchip_pmu_info {
> > > >
> > > >    	const struct rockchip_domain_info *domain_info;
> > > >
> > > >    };
> > > >
> > > > +#define MAX_QOS_NODE_NUM	20
> > > > +#define MAX_QOS_REGS_NUM	5
> > > > +#define QOS_PRIORITY		0x08
> > > > +#define QOS_MODE		0x0c
> > > > +#define QOS_BANDWIDTH		0x10
> > > > +#define QOS_SATURATION		0x14
> > > > +#define QOS_EXTCONTROL		0x18
> > > > +
> > > >
> > > >    struct rockchip_pm_domain {
> > > >
> > > >    	struct generic_pm_domain genpd;
> > > >    	const struct rockchip_domain_info *info;
> > > >    	struct rockchip_pmu *pmu;
> > > >
> > > > +	int num_qos;
> > > > +	struct regmap *qos_regmap[MAX_QOS_NODE_NUM];
> > > > +	u32 qos_save_regs[MAX_QOS_NODE_NUM][MAX_QOS_REGS_NUM];
> > >
> > > struct regmap **qos_regmap;
> > > u32 *qos_save_regs;
> >
> > when we save and restore qos registers we need save five regs for every
> > qos. like this :
> > for (i = 0; i < pd->num_qos; i++) {
> > 		regmap_read(pd->qos_regmap[i],
> > 			    QOS_PRIORITY,
> > 			    &pd->qos_save_regs[i][0]);
> > 		regmap_read(pd->qos_regmap[i],
> > 			    QOS_MODE,
> > 			    &pd->qos_save_regs[i][1]);
> > 		regmap_read(pd->qos_regmap[i],
> > 			    QOS_BANDWIDTH,
> > 			    &pd->qos_save_regs[i][2]);
> > 		regmap_read(pd->qos_regmap[i],
> > 			    QOS_SATURATION,
> > 			    &pd->qos_save_regs[i][3]);
> > 		regmap_read(pd->qos_regmap[i],
> > 			    QOS_EXTCONTROL,
> > 			    &pd->qos_save_regs[i][4]);
> > 	}
> > so we can not define qos_save_regs like u32 *qos_save_regs;,
> > and apply buff like
> > pd->qos_save_regs = kcalloc(pd->num_qos * MAX_QOS_REGS_NUM, sizeof(u32),
> > GFP_KERNEL);
>
> so how about simply swapping indices and doing it like
>
> u32 *qos_save_regs[MAX_QOS_REGS_NUM];
>
> for (i = 0; i < MAX_QOS_REGS_NUM; i++) {
> 	qos_save_regs[i] = kcalloc(pd->num_qos, sizeof(u32));
> 	/* error handling here */
> }
>
> ...
> 		regmap_read(pd->qos_regmap[i],
> 			    QOS_SATURATION,
> 			    &pd->qos_save_regs[3][i]);
> ...

I agree with you on this modification.

> Asked the other way around, how did you measure to set MAX_QOS_REGS_NUM to
> 20? From looking at the rk3399 TRM, it seems there are only 38 QoS
> generators on the SoC in general (24 on the rk3288 with PD_VIO having a
> maximum of 9 qos generators), so preparing for 20 seems a bit overkill ;-)
About the MAX_QOS_NODE_NUM I also have some uncertaibty.
Although there are only 38 QoS on the RK3399(24 on the rk3288),but not 
all of the pd need to power on/off.So not all QOS need save and restore.
So about the MAX_QOS_NODE_NUM, what do you suggest.

MAX_QOS_REGS_NUM is 5 because the QOS register is just 5 need save and 
restore.
like :
#define QOS_PRIORITY		0x08
#define QOS_MODE		0x0c
#define QOS_BANDWIDTH		0x10
#define QOS_SATURATION		0x14
#define QOS_EXTCONTROL		0x18
> Heiko