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

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Message-ID: <DB3PR0402MB3916F906513074C97A8B4AA7F5D00@DB3PR0402MB3916.eurprd04.prod.outlook.com>
Date:   Fri, 24 Apr 2020 02:53:39 +0000
From:   Anson Huang <anson.huang@....com>
To:     Aisheng Dong <aisheng.dong@....com>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "festevam@...il.com" <festevam@...il.com>,
        "ben.dooks@...ethink.co.uk" <ben.dooks@...ethink.co.uk>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     dl-linux-imx <linux-imx@....com>
Subject: RE: [PATCH 2/2] firmware: imx: MU IRQ group number should be 7



> Subject: RE: [PATCH 2/2] firmware: imx: MU IRQ group number should be 7
> 
> > From: Anson Huang <anson.huang@....com>
> > Sent: Friday, April 24, 2020 10:36 AM
> >
> > > -----Original Message-----
> > > From: Aisheng Dong <aisheng.dong@....com>
> > > Sent: 2020年4月24日 10:33
> > > To: Anson Huang <anson.huang@....com>; shawnguo@...nel.org;
> > > s.hauer@...gutronix.de; kernel@...gutronix.de; festevam@...il.com;
> > > ben.dooks@...ethink.co.uk; linux-arm-kernel@...ts.infradead.org;
> > > linux-kernel@...r.kernel.org
> > > Cc: dl-linux-imx <linux-imx@....com>
> > > Subject: RE: [PATCH 2/2] firmware: imx: MU IRQ group number should
> > > be
> > > 7
> > >
> > > > From: Anson Huang <Anson.Huang@....com>
> > > > 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@....com>
> > >
> > > 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.

I don't agree this, if SCFW NOT support it, it should fix from SCFW. This is aligned with our
internal tree.

Anson