linux-kernel - Aw: Re: [net-next v4 3/3] net: ethernet: mtk_eth_soc: change code to skip first IRQ completely

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Message-ID: <trinity-98989ec6-5b15-49ab-b7e0-60e5e23dd82b-1750238087001@trinity-msg-rest-gmx-gmx-live-847b5f5c86-t48nw>
Date: Wed, 18 Jun 2025 09:14:47 +0000
From: Frank Wunderlich <frank-w@...lic-files.de>
To: horms@...nel.org, linux@...web.de
Cc: nbd@....name, sean.wang@...iatek.com, lorenzo@...nel.org,
 andrew+netdev@...n.ch, davem@...emloft.net, edumazet@...gle.com,
 kuba@...nel.org, pabeni@...hat.com, matthias.bgg@...il.com,
 angelogioacchino.delregno@...labora.com, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-mediatek@...ts.infradead.org, daniel@...rotopia.org,
 arinc.unal@...nc9.com
Subject: Aw: Re: [net-next v4 3/3] net: ethernet: mtk_eth_soc: change code
 to skip first IRQ completely

Hi Simon,

thanks for your review

> Gesendet: Mittwoch, 18. Juni 2025 um 10:35
> Von: "Simon Horman" <horms@...nel.org>
> Betreff: Re: [net-next v4 3/3] net: ethernet: mtk_eth_soc: change code to skip first IRQ completely
>
> On Mon, Jun 16, 2025 at 10:07:36AM +0200, Frank Wunderlich wrote:
> > From: Frank Wunderlich <frank-w@...lic-files.de>
> > 
> > On SoCs without MTK_SHARED_INT capability (mt7621 + mt7628) the first
> > IRQ (eth->irq[0]) was read but never used. Do not read it and reduce
> > the IRQ-count to 2 because of skipped index 0.
> 
> Describing the first IRQ as read seems a bit confusing to me - do we read
> it? And saying get or got seems hard to parse. So perhaps something like
> this would be clearer?
> 
> ... platform_get_irq() is called for the first IRQ (eth->irq[0]) but
> it is never used.

ok, i change it in next version

> > 
> > Signed-off-by: Frank Wunderlich <frank-w@...lic-files.de>
> > ---
> > v4:
> > - drop >2 condition as max is already 2 and drop the else continue
> > - update comment to explain which IRQs are taken in legacy way
> > ---
> >  drivers/net/ethernet/mediatek/mtk_eth_soc.c | 20 ++++++++++++++++----
> >  drivers/net/ethernet/mediatek/mtk_eth_soc.h |  4 ++--
> >  2 files changed, 18 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> > index 3ecb399dcf81..f3fcbb00822c 100644
> > --- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> > +++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> > @@ -3341,16 +3341,28 @@ static int mtk_get_irqs(struct platform_device *pdev, struct mtk_eth *eth)
> >  {
> >  	int i;
> >  
> > +	/* future SoCs beginning with MT7988 should use named IRQs in dts */
> 
> Perhaps this comment belongs in the patch that adds support for named IRQs.

also thought that after sending it :)

> >  	eth->irq[MTK_ETH_IRQ_TX] = platform_get_irq_byname(pdev, "tx");
> >  	eth->irq[MTK_ETH_IRQ_RX] = platform_get_irq_byname(pdev, "rx");
> >  	if (eth->irq[MTK_ETH_IRQ_TX] >= 0 && eth->irq[MTK_ETH_IRQ_RX] >= 0)
> >  		return 0;
> >  
> > +	/* legacy way:
> > +	 * On MTK_SHARED_INT SoCs (MT7621 + MT7628) the first IRQ is taken from
> > +	 * devicetree and used for rx+tx.
> > +	 * On SoCs with non-shared IRQ the first was not used, second entry is
> > +	 * TX and third is RX.
> 
> Maybe I am slow. But I had a bit of trouble parsing this.
> Perhaps this is clearer?
> 
>         * devicetree and used for both RX and TX - it is shared.
> 	* On SoCs with non-shared IRQs the first entry is not used,
>         * the second is for TX, and the third is for RX.

I would also move this comment in first patch with your changes requested.

/* legacy way:
 * On MTK_SHARED_INT SoCs (MT7621 + MT7628) the first IRQ is taken from
 * devicetree and used for both RX and TX - it is shared.
 * On SoCs with non-shared IRQs the first entry is not used,
 * the second is for TX, and the third is for RX.
 */

i can keep your RB there?

> > +	 */
> > +
> >  	for (i = 0; i < MTK_ETH_IRQ_MAX; i++) {
> > -		if (MTK_HAS_CAPS(eth->soc->caps, MTK_SHARED_INT) && i > 0)
> > -			eth->irq[i] = eth->irq[MTK_ETH_IRQ_SHARED];
> > -		else
> > -			eth->irq[i] = platform_get_irq(pdev, i);
> > +		if (MTK_HAS_CAPS(eth->soc->caps, MTK_SHARED_INT)) {
> > +			if (i == 0)
> > +				eth->irq[MTK_ETH_IRQ_SHARED] = platform_get_irq(pdev, i);
> > +			else
> > +				eth->irq[i] = eth->irq[MTK_ETH_IRQ_SHARED];
> > +		} else {
> > +			eth->irq[i] = platform_get_irq(pdev, i + 1);
> > +		}
> >  
> >  		if (eth->irq[i] < 0) {
> >  			dev_err(&pdev->dev, "no IRQ%d resource found\n", i);

code changes are OK?

regards Frank