linux-kernel - Re: [net-next v1] net: ethernet: mtk_eth

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Message-ID: <E6B6CB88-4B47-455D-9554-DE9BFC209454@public-files.de>
Date: Sat, 14 Jun 2025 10:38:28 +0200
From: Frank Wunderlich <frank-w@...lic-files.de>
To: Lorenzo Bianconi <lorenzo@...nel.org>, Frank Wunderlich <linux@...web.de>
CC: Felix Fietkau <nbd@....name>, Sean Wang <sean.wang@...iatek.com>,
 Andrew Lunn <andrew+netdev@...n.ch>, "David S. Miller" <davem@...emloft.net>,
 Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
 Paolo Abeni <pabeni@...hat.com>, Matthias Brugger <matthias.bgg@...il.com>,
 AngeloGioacchino Del Regno <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
Subject: Re: [net-next v1] net: ethernet: mtk_eth_soc: support named IRQs

Am 14. Juni 2025 09:48:58 MESZ schrieb Lorenzo Bianconi <lorenzo@...nel.org>:
>> From: Frank Wunderlich <frank-w@...lic-files.de>
>> 
>> Add named interrupts and keep index based fallback for exiting devicetrees.
>> 
>> Currently only rx and tx IRQs are defined to be used with mt7988, but
>> later extended with RSS/LRO support.
>> 
>> Signed-off-by: Frank Wunderlich <frank-w@...lic-files.de>
>> ---
>>  drivers/net/ethernet/mediatek/mtk_eth_soc.c | 24 +++++++++++++--------
>>  1 file changed, 15 insertions(+), 9 deletions(-)
>> 
>> diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
>> index b76d35069887..fcec5f95685e 100644
>> --- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
>> +++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
>> @@ -5106,17 +5106,23 @@ static int mtk_probe(struct platform_device *pdev)
>>  		}
>>  	}
>>  
>> -	for (i = 0; i < 3; i++) {
>> -		if (MTK_HAS_CAPS(eth->soc->caps, MTK_SHARED_INT) && i > 0)
>> -			eth->irq[i] = eth->irq[0];
>> -		else
>> -			eth->irq[i] = platform_get_irq(pdev, i);
>> -		if (eth->irq[i] < 0) {
>> -			dev_err(&pdev->dev, "no IRQ%d resource found\n", i);
>> -			err = -ENXIO;
>> -			goto err_wed_exit;
>> +	eth->irq[1] = platform_get_irq_byname(pdev, "tx");
>> +	eth->irq[2] = platform_get_irq_byname(pdev, "rx");
>
>Hi Frank,
>
>doing so you are not setting eth->irq[0] for MT7988 devices but it is actually
>used in mtk_add_mac() even for non-MTK_SHARED_INT devices. I guess we can reduce
>the eth->irq array size to 2 and start from 0 even for the MT7988 case.
>What do you think?

Hi Lorenzo,

Thank you for reviewing my patch

I had to leave flow compatible with this:

<https://github.com/frank-w/BPI-Router-Linux/blob/bd7e1983b9f0a69cf47cc9b9631138910d6c1d72/drivers/net/ethernet/mediatek/mtk_eth_soc.c#L5176>

Here the irqs are taken from index 1 and 2 for
 registration (!shared_int else only 0). So i avoided changing the
 index,but yes index 0 is unset at this time.

I guess the irq0 is not really used here...
I tested the code on bpi-r4 and have traffic
 rx+tx and no crash.
 imho this field is not used on !shared_int
 because other irq-handlers are used and
 assigned in position above.

It looks like the irq[0] is read before...there is a
 message printed for mediatek frame engine
 which uses index 0 and shows an irq 102 on
 index way and 0 on named version...but the
 102 in index way is not visible in /proc/interrupts.
So imho this message is misleading.

Intention for this patch is that irq 0 and 3 on
 mt7988 (sdk) are reserved (0 is skipped on 
!shared_int and 3 never read) and should imho
 not listed in devicetree. For further cleaner
 devicetrees (with only needed irqs) and to
 extend additional irqs for rss/lro imho irq
 names make it better readable.

>Regards,
>Lorenzo
>
>> +	if (eth->irq[1] < 0 || eth->irq[2] < 0) {
>> +		for (i = 0; i < 3; i++) {
>> +			if (MTK_HAS_CAPS(eth->soc->caps, MTK_SHARED_INT) && i > 0)
>> +				eth->irq[i] = eth->irq[0];
>> +			else
>> +				eth->irq[i] = platform_get_irq(pdev, i);
>> +
>> +			if (eth->irq[i] < 0) {
>> +				dev_err(&pdev->dev, "no IRQ%d resource found\n", i);
>> +				err = -ENXIO;
>> +				goto err_wed_exit;
>> +			}
>>  		}
>>  	}
>> +
>>  	for (i = 0; i < ARRAY_SIZE(eth->clks); i++) {
>>  		eth->clks[i] = devm_clk_get(eth->dev,
>>  					    mtk_clks_source_name[i]);
>> -- 
>> 2.43.0
>> 

regards Frank