linux-kernel - Re: [PATCH net-next v2 3/3] net: ethernet: mtk_eth

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Message-ID: <aGLVPo9M-RhTowmw@makrotopia.org>
Date: Mon, 30 Jun 2025 19:19:42 +0100
From: Daniel Golle <daniel@...rotopia.org>
To: Simon Horman <horms@...nel.org>
Cc: Felix Fietkau <nbd@....name>,
	Frank Wunderlich <frank-w@...lic-files.de>,
	Eric Woudstra <ericwouds@...il.com>, Elad Yifee <eladwf@...il.com>,
	Bo-Cun Chen <bc-bocun.chen@...iatek.com>,
	Sky Huang <skylake.huang@...iatek.com>,
	Sean Wang <sean.wang@...iatek.com>,
	Lorenzo Bianconi <lorenzo@...nel.org>,
	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
Subject: Re: [PATCH net-next v2 3/3] net: ethernet: mtk_eth_soc: use genpool
 allocator for SRAM

On Mon, Jun 30, 2025 at 05:29:59PM +0100, Simon Horman wrote:
> On Sun, Jun 29, 2025 at 11:22:44PM +0100, Daniel Golle wrote:
> > Use a dedicated "mmio-sram" and the genpool allocator instead of
> > open-coding SRAM allocation for DMA rings.
> > Keep support for legacy device trees but notify the user via a
> > warning to update.
> > 
> > Co-developed-by: Frank Wunderlich <frank-w@...lic-files.de>
> > Signed-off-by: Frank Wunderlich <frank-w@...lic-files.de>
> > Signed-off-by: Daniel Golle <daniel@...rotopia.org>
> > ---
> > v2: fix return type of mtk_dma_ring_alloc() in case of error
> > 
> >  drivers/net/ethernet/mediatek/mtk_eth_soc.c | 120 +++++++++++++-------
> >  drivers/net/ethernet/mediatek/mtk_eth_soc.h |   4 +-
> >  2 files changed, 84 insertions(+), 40 deletions(-)
> > 
> > diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> 
> ...
> 
> > @@ -5117,16 +5148,27 @@ static int mtk_probe(struct platform_device *pdev)
> >  			err = -EINVAL;
> >  			goto err_destroy_sgmii;
> >  		}
> > +
> >  		if (MTK_HAS_CAPS(eth->soc->caps, MTK_SRAM)) {
> > -			if (mtk_is_netsys_v3_or_greater(eth)) {
> > -				res_sram = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> > -				if (!res_sram) {
> > -					err = -EINVAL;
> > -					goto err_destroy_sgmii;
> > +			eth->sram_pool = of_gen_pool_get(pdev->dev.of_node, "sram", 0);
> > +			if (!eth->sram_pool) {
> > +				if (!mtk_is_netsys_v3_or_greater(eth)) {
> > +					/*
> > +					 * Legacy support for missing 'sram' node in DT.
> > +					 * SRAM is actual memory and supports transparent access
> > +					 * just like DRAM. Hence we don't require __iomem being
> > +					 * set and don't need to use accessor functions to read from
> > +					 * or write to SRAM.
> > +					 */
> > +					eth->sram_base = (void __force *)eth->base +
> > +							 MTK_ETH_SRAM_OFFSET;
> > +					eth->phy_scratch_ring = res->start + MTK_ETH_SRAM_OFFSET;
> > +					dev_warn(&pdev->dev,
> > +						 "legacy DT: using hard-coded SRAM offset.\n");
> > +				} else {
> > +					dev_err(&pdev->dev, "Could not get SRAM pool\n");
> > +					return -ENODEV;
> 
> Hi Daniel,
> 
> Rather than returning, should this
> jump to err_destroy_sgmii to avoid leaking resources?

Yes, you are right. I'll fix that in v3.