From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793001059; b=Ohsb2Lg1ocTRMCbxjAN9zvPTba5aoshGOii98K7jvJn2mg3DsP1TerOGWZetxUa9U1n+ t9sYaF0Qq4XtOoWmBS2W511h1x0r4VxmFImUNgvBzjPWq2pGTazOvJcTq5R2Cr/YMIXwc UB9GHUhEasu/t4p7TAeEEjCsPpbxl0v1R1VxoBezEtBrXKZiaR1/KJSbmCPhC3EH6S0Km eluFco3+SpBIdqFQy2wmxKL4qHbXyOM2SJiUl1GyPBFab+OU3NbX3CATkGWQgVcnlJXwm e1xszZWOt1HOpXpJfntHOkMlIeexxW93KWonkMRUyoebKvUyxb/aMW/UUqast1pKs5Q== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793001059; h=Received:DKIM-Signature:Date:From:To:Cc:Subject:Message-ID: References:MIME-Version:Content-Type:Content-Disposition:In-Reply-To; bh=GSs4SC8xEvXxzc6tb3y0SEMQgJxrl8ZSN7tzilEn+Eo=; b=3pXrX6ErOwh2rDOvhAwD32i3nuAwXsSjWEDDYdSD+LPrvAGece+IF0/Pl6KvZg/0Wn2m zXsoKaaw6fQIzoFHJ/C56Iz+iHN98g1iEgEJr74YoJvlWoeu2RReYc7rmXwEBfm3g81Vn d5zqM8ipCsyBMKNZlbfPx3DkB4qnTpXw0EFGtnAWKGTaEVClWLWMBYyrRRvakNoIVvPrh C2L1yIJGXFbib6q+Zrtd0IATmCcMwUp3tbdYUiuyOitqB0c9aB/+Bp4xx4kxpiR+Jnmpl ttrPIy3+Xqt4Zo2B+UD+Vd6uWOvEHU5TaZ7dDW0Rmq3xlVEbMRQ1kAegErHVxPghcZA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Kw2YFF7S; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 51E1C606A31B; Mon, 26 Oct 2026 07:50:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Kw2YFF7S Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5F5D21F01825; Mon, 26 Oct 2026 07:50:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793001058; bh=GSs4SC8xEvXxzc6tb3y0SEMQgJxrl8ZSN7tzilEn+Eo=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=Kw2YFF7SxFhk61E+XcdH8MBJU5Uc/8h26oi7o7fo0V/QjOLivTNhOjXd4oxSKtWmo TDOwAnHtn+tupqC3ENK/PzNjzAuLs/6boivj2cb44g4CWLeFmjFfe4qZZ5QyEZEE0U Y7hFDO2UcS8rNGorC8gC8mujud2i42mt59/cPei12CLO0arqT/SyfnYC9ll8w1qdg4 hvXmMy/3rpwMEFAWg7D5yGkgdBIDIjew2h8Xr4b0wil4qqxrWe7q70RwTVZwBjrdlI w/vqiZODz5TkQSdyrUG9sScI45GRiKP0qiV9SMNXUBS444al4GYVHiIPikMnoyIfhC osaOufWgrm2zA== Date: Mon, 26 Oct 2026 08:50:56 +0100 From: Lorenzo Bianconi To: Chris Scott Cc: netdev@vger.kernel.org, andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@kernel.org, kuba@kernel.org, pabeni@redhat.com, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, matthias.bgg@gmail.com, angelogioacchino.delregno@collabora.com, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, pawlik.dan@gmail.com, zhengping.zhang@airoha.com Subject: Re: [RFC net-next 3/3] net: airoha: npu: use coherent memory for mailbox messages Message-ID: References: <20261024154150.45733-1-gilroyscott1970@gmail.com> <20261024154150.45733-4-gilroyscott1970@gmail.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="ks8RgjNESd8HpSsU" Content-Disposition: inline In-Reply-To: <20261024154150.45733-4-gilroyscott1970@gmail.com> --ks8RgjNESd8HpSsU Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable > From: Daniel Pawlik >=20 > airoha_npu_send_msg() maps the caller's kzalloc() buffer with > DMA_BIDIRECTIONAL. These buffers are small and not cacheline aligned, > so on arm64 the mapping bounces through swiotlb. On a 2 GiB EN7581 > board the default swiotlb pool sits above 0xc0000000 (0xff6cf000 on > W1700K), outside the 0x80000000-0xbfffffff window the NPU can address; > higher addresses alias the lower 1 GiB. On W1700K + MT7996 this makes > WLAN_FUNC_GET_WAIT_NPU_VERSION read back 0.0 and mt76 does not bind > NPU offload. >=20 > Allocate one coherent buffer per NPU core at probe and reuse it under > the per-core mailbox lock. With the previous patch it comes from the > NPU DMA pool, inside the window. airoha_npu_send_msg() is also called > from PPE foe_commit under spin_lock_bh(), which rules out a per-message > GFP_ATOMIC coherent allocation. >=20 > Add __airoha_npu_send_msg() with an optional reply buffer so GET > callers copy only the trailing response payload; airoha_npu_send_msg() > keeps copying the whole buffer back, like the bidirectional mapping. >=20 > The original version of this patch was written with Cursor (composer-2); > it was rebased onto net-next and its commit message rewritten with > Claude (Anthropic). >=20 > Link: https://lore.kernel.org/r/20260809152813.585797-1-pawlik.dan@gmail.= com > Link: https://lore.kernel.org/r/atCRsquzA1UxSpCc@mediatek.com > Signed-off-by: Daniel Pawlik > Signed-off-by: Chris Scott > --- > drivers/net/ethernet/airoha/airoha_npu.c | 65 +++++++++++++++++------ > include/linux/soc/airoha/airoha_offload.h | 3 ++ > 2 files changed, 51 insertions(+), 17 deletions(-) >=20 > diff --git a/drivers/net/ethernet/airoha/airoha_npu.c b/drivers/net/ether= net/airoha/airoha_npu.c > index 069fd60680..3d1aa63dd5 100644 > --- a/drivers/net/ethernet/airoha/airoha_npu.c > +++ b/drivers/net/ethernet/airoha/airoha_npu.c > @@ -24,6 +24,12 @@ > #define NPU_EN7581_FIRMWARE_RV32_MAX_SIZE 0x200000 > #define NPU_EN7581_FIRMWARE_DATA_MAX_SIZE 0x10000 > #define NPU_DUMP_SIZE 512 > +/* > + * Mailbox DMA payload size. Covers sizeof(struct ppe_mbox_data) (28) and > + * WLAN TLV messages (header + payload); largest in-tree WLAN payload to= day > + * is 16 bytes (INODE_TXRX_REG_ADDR). Keep headroom for future commands. > + */ > +#define AIROHA_NPU_MBOX_SIZE 256 > =20 > #define REG_NPU_LOCAL_SRAM 0x0 > =20 > @@ -161,23 +167,32 @@ struct wlan_mbox_data { > DECLARE_FLEX_ARRAY(u8, d); > }; > =20 > -static int airoha_npu_send_msg(struct airoha_npu *npu, int func_id, > - void *p, int size) > +static int __airoha_npu_send_msg(struct airoha_npu *npu, int func_id, > + const void *data, int len, void *reply, > + u16 reply_len) > { > - u16 core =3D 0; /* FIXME */ > - u32 val, offset =3D core << 4; > - dma_addr_t dma_addr; > + struct airoha_npu_core *core =3D &npu->cores[0]; /* FIXME: core */ > + u32 val, offset =3D 0; > int ret; > =20 > - dma_addr =3D dma_map_single(npu->dev, p, size, DMA_BIDIRECTIONAL); > - ret =3D dma_mapping_error(npu->dev, dma_addr); > - if (ret) > - return ret; > + if (len > AIROHA_NPU_MBOX_SIZE) > + return -EINVAL; > + > + if (reply && reply_len > len) > + return -EINVAL; > + > + /* > + * The NPU only reaches DRAM at 0x80000000-0xbfffffff; a streaming > + * mapping of the caller buffer may bounce through swiotlb outside > + * that window. Use the probe-time coherent buffer, which comes from > + * the NPU DMA pool when one is declared. > + */ > + spin_lock_bh(&core->lock); > =20 > - spin_lock_bh(&npu->cores[core].lock); > + memcpy(core->buf, data, len); > =20 > - regmap_write(npu->regmap, REG_CR_MBQ0_CTRL(0) + offset, dma_addr); > - regmap_write(npu->regmap, REG_CR_MBQ0_CTRL(1) + offset, size); > + regmap_write(npu->regmap, REG_CR_MBQ0_CTRL(0) + offset, core->addr); > + regmap_write(npu->regmap, REG_CR_MBQ0_CTRL(1) + offset, len); > regmap_read(npu->regmap, REG_CR_MBQ0_CTRL(2) + offset, &val); > regmap_write(npu->regmap, REG_CR_MBQ0_CTRL(2) + offset, val + 1); > val =3D FIELD_PREP(MBOX_MSG_FUNC_ID, func_id) | MBOX_MSG_WAIT_RSP; > @@ -190,13 +205,21 @@ static int airoha_npu_send_msg(struct airoha_npu *n= pu, int func_id, > if (!ret && FIELD_GET(MBOX_MSG_STATUS, val) !=3D NPU_MBOX_SUCCESS) > ret =3D -EINVAL; > =20 > - spin_unlock_bh(&npu->cores[core].lock); > + /* Copy the trailing reply_len bytes of the response. */ > + if (!ret && reply) > + memcpy(reply, core->buf + len - reply_len, reply_len); > =20 > - dma_unmap_single(npu->dev, dma_addr, size, DMA_BIDIRECTIONAL); > + spin_unlock_bh(&core->lock); > =20 > return ret; > } > =20 > +static int airoha_npu_send_msg(struct airoha_npu *npu, int func_id, > + void *data, int len) > +{ > + return __airoha_npu_send_msg(npu, func_id, data, len, data, len); IIUC airoha_npu_send_msg() is used when we do not expect any reply, correct= ? In this case we should have: return __airoha_npu_send_msg(npu, func_id, data, len, NULL, len); Am I missing something? Regards, Lorenzo > +} > + > static int airoha_npu_load_firmware(struct device *dev, void __iomem *ad= dr, > const char *fw_name, int fw_max_size) > { > @@ -500,9 +523,8 @@ static int airoha_npu_wlan_msg_get(struct airoha_npu = *npu, int ifindex, > wlan_data->func_type =3D NPU_OP_GET; > wlan_data->func_id =3D func_id; > =20 > - err =3D airoha_npu_send_msg(npu, NPU_FUNC_WIFI, wlan_data, len); > - if (!err) > - memcpy(data, wlan_data->d, data_len); > + err =3D __airoha_npu_send_msg(npu, NPU_FUNC_WIFI, wlan_data, len, > + data, data_len); > kfree(wlan_data); > =20 > return err; > @@ -794,6 +816,15 @@ static int airoha_npu_probe(struct platform_device *= pdev) > return err; > } > =20 > + for (i =3D 0; i < ARRAY_SIZE(npu->cores); i++) { > + struct airoha_npu_core *core =3D &npu->cores[i]; > + > + core->buf =3D dmam_alloc_coherent(dev, AIROHA_NPU_MBOX_SIZE, > + &core->addr, GFP_KERNEL); > + if (!core->buf) > + return -ENOMEM; > + } > + > err =3D airoha_npu_run_firmware(dev, base, &res); > if (err) > return err; > diff --git a/include/linux/soc/airoha/airoha_offload.h b/include/linux/so= c/airoha/airoha_offload.h > index 7589fccfee..16a988ad74 100644 > --- a/include/linux/soc/airoha/airoha_offload.h > +++ b/include/linux/soc/airoha/airoha_offload.h > @@ -173,6 +173,9 @@ struct airoha_npu { > /* protect concurrent npu memory accesses */ > spinlock_t lock; > struct work_struct wdt_work; > + /* Coherent bounce buffer for mailbox cmd/rsp */ > + void *buf; > + dma_addr_t addr; > } cores[NPU_NUM_CORES]; > =20 > int irqs[NPU_NUM_IRQ]; > --=20 > 2.53.0 >=20 --ks8RgjNESd8HpSsU Content-Type: application/pgp-signature; name=signature.asc -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQTquNwa3Txd3rGGn7Y6cBh0uS2trAUCat8GYAAKCRA6cBh0uS2t rAyyAP4vQ0d/lxhDq7vgz5zZvFYc9PWyteGbdUndIq9yHNykLwD9HXcgZ822FdNP cxub3lKtITSN9fGw+qxMyaBJbgcfXgQ= =fVMR -----END PGP SIGNATURE----- --ks8RgjNESd8HpSsU--