From nobody Tue Feb 10 06:25:17 2026 Received: from smtp-out3.simply.com (smtp-out3.simply.com [94.231.106.210]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D7130449ECA; Thu, 22 Jan 2026 12:11:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=94.231.106.210 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769083865; cv=none; b=Id4p3i+zzPcdVAeS0pmU6Z6ttIe5InmnyaCF1j9Xe3EgBwLfnNth9Dwqp3yGKaERjMBzcWNxIMwpIdu74Yvrlr8TXLcsKw70MVO6jG8cIDagbTo4srK+iUpzObMDQ6C/tsYUkE3hPMPcb9rOovwazBRdYysr4YdTaPz4bkwCaFQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769083865; c=relaxed/simple; bh=yzu11Z57nTas90/09+nK6ANfPzkmv2++yiMJl9jG0KU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=CEYbaWxaOYWdpISLSIegXjsFnlPWip7NVqTHcym31Aoy8jDFbTlhDfN1y6qm2ajmQUNUQlrWUtYbylBxMBVYPPpxNXhaZbr1aNyhHarI1okyJcaV9B9v3upbC5w/eKibt7E+teFV78PGrvA8ic5mW/uRFxXbYRwwYBxzdLLSESI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gaisler.com; spf=pass smtp.mailfrom=gaisler.com; dkim=fail (0-bit key) header.d=gaisler.com header.i=@gaisler.com header.b=oHwIpGZT reason="key not found in DNS"; arc=none smtp.client-ip=94.231.106.210 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gaisler.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gaisler.com Authentication-Results: smtp.subspace.kernel.org; dkim=fail reason="key not found in DNS" (0-bit key) header.d=gaisler.com header.i=@gaisler.com header.b="oHwIpGZT" Received: from localhost (localhost [127.0.0.1]) by smtp.simply.com (Simply.com) with ESMTP id 4dxfzG6Y8Rz1FlY3; Thu, 22 Jan 2026 13:10:50 +0100 (CET) Received: from d-5xj5g74.got.gaisler.com.com (h-98-128-223-123.NA.cust.bahnhof.se [98.128.223.123]) by smtp.simply.com (Simply.com) with ESMTPA id 4dxfzG4WSlz1FlY1; Thu, 22 Jan 2026 13:10:50 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gaisler.com; s=simplycom2; t=1769083850; bh=Ifj/YMFPcPFEro+213ka+sB+HgXHGlvN61oSA9++Mfg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=oHwIpGZTpG3v42jznLEsQ3TJ0pb5TXdBS4XK0RU35PzoPMSblXHduooaz6fPhK5w3 oLTUkxdRQA2eMehvMnk0JFUpjjsKy/WEyOJvOWwRSBDle3FsSbu2EJxEGor6WJYeuk 6FRVv49B4dMGvMnv6ne38k05XSaZ3bJk+dN1D9NuSO67CD2uPAqYUPWYnCnV8TYqO3 c56M8UUmEibv1x0mZcMLvrfQsFvbBtS+Fdu9NtuHj3DVXzYc5fSEm5oY9SR7XYDtn/ zRNJ1mkZnjo6lOGxVPZRuepQNaUTD3bY/V2s6Ktrj7k+9I/HXac1JF7yF0c4EfNnh7 C9Ov8n0LjTsKQ== From: Arun Muthusamy To: robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, mkl@pengutronix.de, mailhol@kernel.org Cc: devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-can@vger.kernel.org, Arun Muthusamy Subject: [PATCH v3 15/15] can: grcan: Update echo skb handling to match variable length CANFD frame Date: Thu, 22 Jan 2026 13:10:38 +0100 Message-ID: <20260122121038.7910-16-arun.muthusamy@gaisler.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260122121038.7910-1-arun.muthusamy@gaisler.com> References: <20260122121038.7910-1-arun.muthusamy@gaisler.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Refactor echo socket buffer management by introducing dedicated indices for current and next echo slots. - Introduce "echo_skb_idx" to keep track of the current packet index in the echo buffer, and "next_echo_idx" for the next available slot. - Adjust memory allocation for echo skb to calculate the number of slots based on slot size. - Enhance logic in catch_up_echo_skb() to correctly process and free echo skbs. - Initialize "next_echo_idx" in grcan_set_mode() to ensure proper starting conditions when the device enters proper modes. - Improve memory and index handling in grcan_start_xmit() and added a check to stop the network queue when necessary. Signed-off-by: Arun Muthusamy --- drivers/net/can/grcan.c | 51 ++++++++++++++++++++++++++++++----------- 1 file changed, 38 insertions(+), 13 deletions(-) diff --git a/drivers/net/can/grcan.c b/drivers/net/can/grcan.c index 39afb12c50d0..22c86e5d7002 100644 --- a/drivers/net/can/grcan.c +++ b/drivers/net/can/grcan.c @@ -298,6 +298,15 @@ struct grcan_priv { =20 struct sk_buff **echo_skb; /* We allocate this on our own */ =20 + /* + * Since the CAN FD frame has a variable length, this variable is used + * to keep track of the index of the CAN echo skb (socket buffer) frame. + */ + u32 echo_skb_idx; + + /* Next echo skb free slot index */ + u32 next_echo_idx; + /* The echo skb pointer, pointing into echo_skb and indicating which * frames can be echoed back. See the "Notes on the tx cyclic buffer * handling"-comment for grcan_start_xmit for more details. @@ -578,7 +587,7 @@ static int catch_up_echo_skb(struct net_device *dev, in= t budget, bool echo) struct grcan_registers __iomem *regs =3D priv->regs; struct grcan_dma *dma =3D &priv->dma; struct net_device_stats *stats =3D &dev->stats; - int i, work_done; + int work_done; =20 /* Updates to priv->eskbp and wake-ups of the queue needs to * be atomic towards the reads of priv->eskbp and shut-downs @@ -589,19 +598,22 @@ static int catch_up_echo_skb(struct net_device *dev, = int budget, bool echo) for (work_done =3D 0; work_done < budget || budget < 0; work_done++) { if (priv->eskbp =3D=3D txrd) break; - i =3D priv->eskbp / GRCAN_MSG_SIZE; - if (echo) { - /* Normal echo of messages */ - stats->tx_packets++; - stats->tx_bytes +=3D can_get_echo_skb(dev, i, NULL); - } else { - /* For cleanup of untransmitted messages */ - can_free_echo_skb(dev, i, NULL); - } =20 priv->eskbp =3D grcan_ring_add(priv->eskbp, GRCAN_MSG_SIZE, dma->tx.size); txrd =3D grcan_read_reg(®s->txrd); + + /* Grab the packet once the packet is send or free untransmitted packet= */ + if (priv->eskbp =3D=3D txrd) { + if (echo) { + /* Normal echo of messages */ + stats->tx_packets++; + stats->tx_bytes +=3D can_get_echo_skb(dev, priv->echo_skb_idx, NULL); + } else { + /* For cleanup of untransmitted messages */ + can_free_echo_skb(dev, priv->echo_skb_idx, NULL); + } + } } return work_done; } @@ -1109,6 +1121,7 @@ static int grcan_set_mode(struct net_device *dev, enu= m can_mode mode) if (!(priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)) netif_wake_queue(dev); } + priv->next_echo_idx =3D 0; spin_unlock_irqrestore(&priv->lock, flags); return err; } @@ -1120,6 +1133,7 @@ static int grcan_open(struct net_device *dev) struct grcan_priv *priv =3D netdev_priv(dev); struct grcan_dma *dma =3D &priv->dma; unsigned long flags; + u32 nr_echo_slots; int err; =20 /* Allocate memory */ @@ -1130,13 +1144,15 @@ static int grcan_open(struct net_device *dev) return err; } =20 - priv->echo_skb =3D kcalloc(dma->tx.size, sizeof(*priv->echo_skb), + nr_echo_slots =3D dma->tx.size / GRCAN_MSG_SIZE; + + priv->echo_skb =3D kcalloc(nr_echo_slots, sizeof(*priv->echo_skb), GFP_KERNEL); if (!priv->echo_skb) { err =3D -ENOMEM; goto exit_free_dma_buffers; } - priv->can.echo_skb_max =3D dma->tx.size; + priv->can.echo_skb_max =3D nr_echo_slots; priv->can.echo_skb =3D priv->echo_skb; =20 /* Get can device up */ @@ -1575,7 +1591,16 @@ static netdev_tx_t grcan_start_xmit(struct sk_buff *= skb, * can_put_echo_skb would be an error unless other measures are * taken. */ - can_put_echo_skb(skb, dev, slotindex, 0); + + priv->echo_skb_idx =3D priv->next_echo_idx; + + can_put_echo_skb(skb, dev, priv->next_echo_idx, 0); + + /* Move to the next index in the echo skb buffer */ + priv->next_echo_idx =3D (priv->next_echo_idx + 1) % priv->can.echo_skb_ma= x; + + if (priv->can.echo_skb[priv->echo_skb_idx]) + netif_stop_queue(dev); =20 /* Make sure everything is written before allowing hardware to * read from the memory --=20 2.51.0