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Date: Mon, 27 Jul 2020 15:59:13 +0300
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Vadym Kochan <vadym.kochan@...ision.eu>
Cc: "David S. Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>,
Jiri Pirko <jiri@...lanox.com>,
Ido Schimmel <idosch@...lanox.com>,
Andrew Lunn <andrew@...n.ch>,
Oleksandr Mazur <oleksandr.mazur@...ision.eu>,
Serhiy Boiko <serhiy.boiko@...ision.eu>,
Serhiy Pshyk <serhiy.pshyk@...ision.eu>,
Volodymyr Mytnyk <volodymyr.mytnyk@...ision.eu>,
Taras Chornyi <taras.chornyi@...ision.eu>,
Andrii Savka <andrii.savka@...ision.eu>,
netdev <netdev@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Mickey Rachamim <mickeyr@...vell.com>
Subject: Re: [net-next v4 1/6] net: marvell: prestera: Add driver for Prestera
family ASIC devices
On Mon, Jul 27, 2020 at 3:23 PM Vadym Kochan <vadym.kochan@...ision.eu> wrote:
>
> Marvell Prestera 98DX326x integrates up to 24 ports of 1GbE with 8
> ports of 10GbE uplinks or 2 ports of 40Gbps stacking for a largely
> wireless SMB deployment.
>
> The current implementation supports only boards designed for the Marvell
> Switchdev solution and requires special firmware.
>
> The core Prestera switching logic is implemented in prestera_main.c,
> there is an intermediate hw layer between core logic and firmware. It is
> implemented in prestera_hw.c, the purpose of it is to encapsulate hw
> related logic, in future there is a plan to support more devices with
> different HW related configurations.
>
> This patch contains only basic switch initialization and RX/TX support
> over SDMA mechanism.
>
> Currently supported devices have DMA access range <= 32bit and require
> ZONE_DMA to be enabled, for such cases SDMA driver checks if the skb
> allocated in proper range supported by the Prestera device.
>
> Also meanwhile there is no TX interrupt support in current firmware
> version so recycling work is scheduled on each xmit.
>
> Port's mac address is generated from the switch base mac which may be
> provided via device-tree (static one or as nvme cell), or randomly
> generated.
...
> Signed-off-by: Andrii Savka <andrii.savka@...ision.eu>
> Signed-off-by: Oleksandr Mazur <oleksandr.mazur@...ision.eu>
> Signed-off-by: Serhiy Boiko <serhiy.boiko@...ision.eu>
> Signed-off-by: Serhiy Pshyk <serhiy.pshyk@...ision.eu>
> Signed-off-by: Taras Chornyi <taras.chornyi@...ision.eu>
> Signed-off-by: Volodymyr Mytnyk <volodymyr.mytnyk@...ision.eu>
> Signed-off-by: Vadym Kochan <vadym.kochan@...ision.eu>
This needs more work. You have to really understand the role of each
person in the above list.
I highly recommend (re-)read sections 11-13 of Submitting Patches.
...
> +/* SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
The idea of SPDX is to have it as a separate (standalone) comment.
...
> +enum prestera_event_type {
> + PRESTERA_EVENT_TYPE_UNSPEC,
> +
> + PRESTERA_EVENT_TYPE_PORT,
> + PRESTERA_EVENT_TYPE_RXTX,
> +
> + PRESTERA_EVENT_TYPE_MAX,
Commas in the terminators are not good.
> +};
...
> +#include "prestera_dsa.h"
The idea that you include more generic headers earlier than more custom ones.
> +#include <linux/string.h>
> +#include <linux/bitops.h>
> +#include <linux/bitfield.h>
> +#include <linux/errno.h>
Perhaps ordered?
...
> +/* TrgDev[4:0] = {Word0[28:24]} */
> + * SrcPort/TrgPort[7:0] = {Word2[20], Word1[11:10], Word0[23:19]}
> +/* bits 13:15 -- UP */
> +/* bits 0:11 -- VID */
These are examples of useless comments.
...
> + dsa->vlan.is_tagged = (bool)FIELD_GET(PRESTERA_W0_IS_TAGGED, words[0]);
> + dsa->vlan.cfi_bit = (u8)FIELD_GET(PRESTERA_W1_CFI_BIT, words[1]);
> + dsa->vlan.vpt = (u8)FIELD_GET(PRESTERA_W0_VPT, words[0]);
> + dsa->vlan.vid = (u16)FIELD_GET(PRESTERA_W0_VID, words[0]);
Do you need those castings?
...
> + struct prestera_msg_event_port *hw_evt;
> +
> + hw_evt = (struct prestera_msg_event_port *)msg;
Can be one line I suppose.
...
> + if (evt->id == PRESTERA_PORT_EVENT_STATE_CHANGED)
> + evt->port_evt.data.oper_state = hw_evt->param.oper_state;
> + else
> + return -EINVAL;
> +
> + return 0;
Perhaps traditional pattern, i.e.
if (...)
return -EINVAL;
...
return 0;
...
> + err = fw_event_parsers[msg->type].func(buf, &evt);
> + if (!err)
> + eh.func(sw, &evt, eh.arg);
Ditto.
> + return err;
...
> + memcpy(&req.param.mac, mac, sizeof(req.param.mac));
Consider to use ether_addr_*() APIs instead of open-coded mem*() ones.
...
> +#define PRESTERA_MTU_DEFAULT 1536
Don't we have global default for this?
...
> +#define PRESTERA_STATS_DELAY_MS msecs_to_jiffies(1000)
It's not _MS.
...
> + if (!is_up)
> + netif_stop_queue(dev);
> +
> + err = prestera_hw_port_state_set(port, is_up);
> +
> + if (is_up && !err)
> + netif_start_queue(dev);
Much better if will look lke
if (is_up) {
...
err = ...(..., true);
if (err)
return err;
...
} else {
return prestera_*(..., false);
}
return 0;
> + return err;
...
> + /* Only 0xFF mac addrs are supported */
> + if (port->fp_id >= 0xFF)
> + goto err_port_init;
You meant 255, right?
Otherwise you have to mentioned is it byte limitation or what?
...
> +static int prestera_switch_set_base_mac_addr(struct prestera_switch *sw)
> +{
> + struct device_node *base_mac_np;
> + struct device_node *np;
> + np = of_find_compatible_node(NULL, NULL, "marvell,prestera");
> + if (np) {
> + base_mac_np = of_parse_phandle(np, "base-mac-provider", 0);
> + if (base_mac_np) {
> + const char *base_mac;
> +
> + base_mac = of_get_mac_address(base_mac_np);
> + of_node_put(base_mac_np);
> + if (!IS_ERR(base_mac))
> + ether_addr_copy(sw->base_mac, base_mac);
> + }
> + }
> +
> + if (!is_valid_ether_addr(sw->base_mac)) {
> + eth_random_addr(sw->base_mac);
> + dev_info(sw->dev->dev, "using random base mac address\n");
> + }
Isn't it device_get_mac_address() reimplementation?
> +
> + return prestera_hw_switch_mac_set(sw, sw->base_mac);
> +}
...
> + err = prestera_switch_init(sw);
> + if (err) {
> + kfree(sw);
> + return err;
> + }
> +
> + return 0;
if (err)
kfree(...);
return err;
Also, check reference counting.
...
> +#define PRESTERA_SDMA_RX_DESC_PKT_LEN(desc) \
> + ((le32_to_cpu((desc)->word2) >> 16) & 0x3FFF)
Why not GENMASK() ?
...
> + if (dma + sizeof(struct prestera_sdma_desc) > sdma->dma_mask) {
> + dev_err(dma_dev, "failed to alloc desc\n");
> + dma_pool_free(sdma->desc_pool, desc, dma);
Better first undo something *then* print a message.
> + return -ENOMEM;
> + }
...
> +static void prestera_sdma_rx_desc_set_len(struct prestera_sdma_desc *desc,
> + size_t val)
> +{
> + u32 word = le32_to_cpu(desc->word2);
> +
> + word = (word & ~GENMASK(15, 0)) | val;
Shouldn't you do traditional pattern?
word = (word & ~mask) | (val & mask);
> + desc->word2 = cpu_to_le32(word);
> +}
...
> + dma = dma_map_single(dev, skb->data, skb->len, DMA_FROM_DEVICE);
> +
Redundant blank line.
> + if (dma_mapping_error(dev, dma))
> + goto err_dma_map;
...
> + pr_warn_ratelimited("received pkt for non-existent port(%u, %u)\n",
> + dev_id, hw_port);
netdev_warn_ratelimited() ? Or something closer to that?
...
> + qmask = GENMASK(qnum - 1, 0);
BIT(qnum) - 1 will produce much better code I suppose.
...
> + if (pkts_done < budget && napi_complete_done(napi, pkts_done))
> + prestera_write(sdma->sw, PRESTERA_SDMA_RX_INTR_MASK_REG,
> + 0xff << 2);
GENMASK() ?
...
> + word = (word & ~GENMASK(30, 16)) | ((len + ETH_FCS_LEN) << 16);
Consider traditional pattern.
...
> + word |= PRESTERA_SDMA_TX_DESC_DMA_OWN << 31;
I hope that was defined with U. Otherwise it's UB.
...
> + new_skb = alloc_skb(len, GFP_ATOMIC | GFP_DMA);
Atomic? Why?
...
> +static int prestera_sdma_tx_wait(struct prestera_sdma *sdma,
> + struct prestera_tx_ring *tx_ring)
> +{
> + int tx_retry_num = 10 * tx_ring->max_burst;
Magic!
> + while (--tx_retry_num) {
> + if (prestera_sdma_is_ready(sdma))
> + return 0;
> +
> + udelay(1);
> + }
unsigned int counter = ...;
do { } while (--counter);
looks better.
Also, why udelay()? Is it atomic context?
> + return -EBUSY;
> +}
...
> + if (!tx_ring->burst--) {
Don't do like this. It makes code harder to understand.
if (tx_ring->...) {
...->burst--;
} else {
...
}
> + tx_ring->burst = tx_ring->max_burst;
> +
> + err = prestera_sdma_tx_wait(sdma, tx_ring);
> + if (err)
> + goto drop_skb_unmap;
> + }
--
With Best Regards,
Andy Shevchenko
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