RE: [PATCH 2/2] firmware: imx: MU IRQ group number should be 7

[Aisheng Dong]

> From: Anson Huang <anson.huang@xxxxxxx>
> Sent: Friday, April 24, 2020 10:36 AM
> 
> > -----Original Message-----
> > From: Aisheng Dong <aisheng.dong@xxxxxxx>
> > Sent: 2020å4æ24æ 10:33
> > To: Anson Huang <anson.huang@xxxxxxx>; shawnguo@xxxxxxxxxx;
> > s.hauer@xxxxxxxxxxxxxx; kernel@xxxxxxxxxxxxxx; festevam@xxxxxxxxx;
> > ben.dooks@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx;
> > linux-kernel@xxxxxxxxxxxxxxx
> > Cc: dl-linux-imx <linux-imx@xxxxxxx>
> > Subject: RE: [PATCH 2/2] firmware: imx: MU IRQ group number should be
> > 7
> >
> > > From: Anson Huang <Anson.Huang@xxxxxxx>
> > > Sent: Friday, April 24, 2020 7:07 AM
> > >
> > > The MU IRQ group number should be 7 instead of 4.
> > >
> > > Signed-off-by: Anson Huang <Anson.Huang@xxxxxxx>
> >
> > Are we using others IRQ group?
> > If not, this change may slow down the irq handling speed.
> 
> The irq handling is using work queue, NOT in ISR, so the speed is NOT that
> sensitive.

SCU IPC is shared by the whole system, each SCU transfer takes about 10~20 us.
Here you may waste 30~60us if not really used.

> The scu group irq driver should provide full functions, as other drivers using it
> may enable the group they want.

Below are extra GROUPs you're going to add:
#define SC_IRQ_GROUP_SYSCTR     4U   /*!< System counter interrupts */
#define SC_IRQ_GROUP_REBOOTED   5U   /*!< Partition reboot complete */
#define SC_IRQ_GROUP_REBOOT     6U   /*!< Partition reboot starting */
Are we really going to use it? It seems I also didn't see any users in downstream tree.

Some functions provided by SCFW may not really used by Linux.
I think I's better to add them when we really need them, otherwise we benefit nothing
But wasting CPU mips.

Regards
Aisheng

> 
> Anson