linux-kernel - Re: [PATCH net-next 07/13] net: fec: fec_probe(): update quirk: bring IRQs in correct order

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Message-ID: <20241017-ambitious-truthful-pegasus-8f1078-mkl@pengutronix.de>
Date: Thu, 17 Oct 2024 08:13:12 +0200
From: Marc Kleine-Budde <mkl@...gutronix.de>
To: Frank Li <Frank.li@....com>
Cc: Wei Fang <wei.fang@....com>, Shenwei Wang <shenwei.wang@....com>, 
	Clark Wang <xiaoning.wang@....com>, "David S. Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>, Richard Cochran <richardcochran@...il.com>, imx@...ts.linux.dev, 
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org, kernel@...gutronix.de
Subject: Re: [PATCH net-next 07/13] net: fec: fec_probe(): update quirk:
 bring IRQs in correct order

On 16.10.2024 22:15:43, Frank Li wrote:
> On Wed, Oct 16, 2024 at 11:51:55PM +0200, Marc Kleine-Budde wrote:
> > With i.MX8MQ and compatible SoCs, the order of the IRQs in the device
> > tree is not optimal. The driver expects the first three IRQs to match
> > their corresponding queue, while the last (fourth) IRQ is used for the
> > PPS:
> >
> > - 1st IRQ: "int0": queue0 + other IRQs
> > - 2nd IRQ: "int1": queue1
> > - 3rd IRQ: "int2": queue2
> > - 4th IRQ: "pps": pps
> >
> > However, the i.MX8MQ and compatible SoCs do not use the
> > "interrupt-names" property and specify the IRQs in the wrong order:
> >
> > - 1st IRQ: queue1
> > - 2nd IRQ: queue2
> > - 3rd IRQ: queue0 + other IRQs
> > - 4th IRQ: pps
> 
> why not fix dts?

Because of compatibility. You could update the fec driver and try to
detect if the IRQs in the DTS are in the "correct" order, but the new
DTS will be incompatible with the old driver.

I'm working on a patch series that updates the fec driver to "per queue
IRQ and NAPI" handling. For this approach it's crucial that the IRQs
match the queue number.

regards,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde          |
Embedded Linux                   | https://www.pengutronix.de |
Vertretung Nürnberg              | Phone: +49-5121-206917-129 |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-9   |

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