netdev - Re: [PATCH net-next v3 08/19] net: ravb: Move the IRQs get and request in the probe function

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Message-ID: <02548b1b-d32c-78b1-f1b6-5fdb505d31bb@omp.ru>
Date: Sun, 7 Jan 2024 21:24:17 +0300
From: Sergey Shtylyov <s.shtylyov@....ru>
To: Claudiu <claudiu.beznea@...on.dev>, <davem@...emloft.net>,
	<edumazet@...gle.com>, <kuba@...nel.org>, <pabeni@...hat.com>,
	<richardcochran@...il.com>, <p.zabel@...gutronix.de>,
	<yoshihiro.shimoda.uh@...esas.com>, <wsa+renesas@...g-engineering.com>
CC: <netdev@...r.kernel.org>, <linux-renesas-soc@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <geert+renesas@...der.be>, Claudiu Beznea
	<claudiu.beznea.uj@...renesas.com>
Subject: Re: [PATCH net-next v3 08/19] net: ravb: Move the IRQs get and
 request in the probe function

On 1/5/24 11:23 AM, Claudiu wrote:

> From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
> 
> The runtime PM implementation will disable clocks at the end of
> ravb_probe(). As some IP variants switch to reset mode as a result of
> setting module standby through clock disable APIs, to implement runtime PM
> the resource parsing and requesting are moved in the probe function and IP
> settings are moved in the open function. This is done because at the end of
> the probe some IP variants will switch anyway to reset mode and the
> registers content is lost. Also keeping only register specific operations
> in the ravb_open()/ravb_close() functions will make them faster.
> 
> Commit moves IRQ requests to ravb_probe() to have all the IRQs ready when
> the interface is open. As now IRQs gets and requests are in a single place
> there is no need to keep intermediary data (like ravb_rx_irqs[] and
> ravb_tx_irqs[] arrays or IRQs in struct ravb_private).

   There's one thing that you probably didn't take into account: after
you call request_irq(), you should be able to handle your IRQ as it's
automatically unmasked, unless you pass IRQF_NO_AUTOEN to request_irq().
Your device may be held i reset or even powered off but if you pass IRQF_SHARED to request_irq() (you do in a single IRQ config), you must
be prepared to get your device's registers read (in order to ascertain
whether it's your IRQ or not). And you can't even pass IRQF_NO_AUTOEN
along with IRQF_SHARED, according to my reading of the IRQ code...

> This is a preparatory change to add runtime PM support for all IP variants.

  I don't readily see why this is necessary for the full-fledged RPM
support...

> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>

   Unfortunately, I have to NAK this patch, at least in its current
form...

[...]

MBR, Sergey