From: marc.zyngier@arm•com (Marc Zyngier)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v2 4/5] irqchip:create irq domain for each mbigen device
Date: Wed, 17 Feb 2016 07:47:40 +0000 [thread overview]
Message-ID: <20160217074740.439c53b4@arm.com> (raw)
In-Reply-To: <56C3F4AC.8020807@huawei.com>
On Wed, 17 Feb 2016 12:18:52 +0800
"majun (F)" <majun258@huawei•com> wrote:
>
>
> ? 2016/2/16 16:50, Marc Zyngier ??:
> > On Tue, 16 Feb 2016 14:37:27 +0800
> > MaJun <majun258@huawei•com> wrote:
> >
> >> From: Ma Jun <majun258@huawei•com>
> [...]
> >> + unsigned int nid;
> >> +
> >> + nid = get_mbigen_nid(hwirq);
> >> +
> >> + if (nid < 4)
> >> + return (nid * 4) + REG_MBIGEN_VEC_OFFSET;
> >> + else
> >> + return (nid - 4) * 4 + REG_MBIGEN_EXT_VEC_OFFSET;
> >> +}
> >> +
> >> +static struct irq_chip mbigen_irq_chip = {
> >> + .name = "mbigen-v1",
> >> +};
> >> +
> >> +static void mbigen_write_msg(struct msi_desc *desc, struct msi_msg *msg)
> >> +{
> >> + /* The address of doorbell is encoded in mbigen register by default
> >> + * So,we don't need to program the doorbell address at here
> >> + * Besides, the event ID is decided by the hardware pin number,
> >> + * we can't change it in software.So, we don't need to encode the
> >> + * event ID in mbigen register.
> >> + */
> >
> > Really? What if tomorrow I decide to change the EventID allocation
> > policy in the ITS driver? Have your HW engineers really baked the
> > behaviour of the Linux driver into the device?
> >
>
> Yes.
> If we really need to support this chip,is there
> any possible solution for this problem?
You would have to provide some sort of lookup table from the
device-tree, or find a way to pass this information down the ITS code.
The real question is: do we take this as it is and fix it once it
breaks? or do we mandate a proper solution before this has a remote
chance of getting in?
At the moment, I don't know, because the idea of hardcoded MSIs is so
wrong and so against the way the whole stack works that I just want to
say no to this and run away.
I need to think.
M.
--
Jazz is not dead. It just smells funny.
next prev parent reply other threads:[~2016-02-17 7:47 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-16 6:37 [PATCH v2 0/5] irqchip: Add support for Hisilicon mbigen v1 chip MaJun
2016-02-16 6:37 ` [PATCH v2 1/5] dt-binding: Change the mbigen binding file to support the mbigen-v1 MaJun
2016-02-16 6:37 ` [PATCH v2 2/5] dt-binding:Rename the mbigen binding file name MaJun
2016-02-16 6:37 ` [PATCH v2 3/5] irqchip: add platform device driver for mbigen device MaJun
2016-02-16 6:37 ` [PATCH v2 4/5] irqchip:create irq domain for each " MaJun
2016-02-16 8:50 ` Marc Zyngier
2016-02-17 4:18 ` majun (F)
2016-02-17 7:47 ` Marc Zyngier [this message]
2016-02-16 6:37 ` [PATCH v2 5/5] irqchip:implement the mbigen irq chip operation functions MaJun
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