On Thu, Feb 22, 2024 at 03:22:14PM +0100, Herve Codina wrote:
> The QMC HDLC driver provides support for HDLC using the QMC (QUICC
> Multichannel Controller) to transfer the HDLC data.
...
> +struct qmc_hdlc {
> + struct device *dev;
> + struct qmc_chan *qmc_chan;
> + struct net_device *netdev;
> + bool is_crc32;
> + spinlock_t tx_lock; /* Protect tx descriptors */
Just wondering if above tx/rx descriptors should be aligned on a cacheline
for DMA?
> + struct qmc_hdlc_desc tx_descs[8];
> + unsigned int tx_out;
> + struct qmc_hdlc_desc rx_descs[4];
> +};
...
> +#define QMC_HDLC_RX_ERROR_FLAGS (QMC_RX_FLAG_HDLC_OVF | \
> + QMC_RX_FLAG_HDLC_UNA | \
> + QMC_RX_FLAG_HDLC_ABORT | \
> + QMC_RX_FLAG_HDLC_CRC)
Wouldn't be slightly better to have it as
#define QMC_HDLC_RX_ERROR_FLAGS \
(QMC_RX_FLAG_HDLC_OVF | QMC_RX_FLAG_HDLC_UNA | \
QMC_RX_FLAG_HDLC_CRC | QMC_RX_FLAG_HDLC_ABORT)
?
...
> + ret = qmc_chan_write_submit(qmc_hdlc->qmc_chan, desc->dma_addr,
> desc->dma_size,
> + qmc_hdlc_xmit_complete, desc);
> + if (ret) {
> + dev_err(qmc_hdlc->dev, "qmc chan write returns %d\n", ret);
> + dma_unmap_single(qmc_hdlc->dev, desc->dma_addr, desc->dma_size,
> DMA_TO_DEVICE);
> + return ret;
I would do other way around, i.e. release resource followed up by printing
a message. Printing a message is a slow operation and may prevent the (soon
freed) resources to be re-used earlier.
> + }
...
> + spin_lock_irqsave(&qmc_hdlc->tx_lock, flags);
Why not using cleanup.h from day 1?
> +end:
This label, in particular, will not be needed with above in place.
> + spin_unlock_irqrestore(&qmc_hdlc->tx_lock, flags);
> + return ret;
> +}
...
> + /* Queue as many recv descriptors as possible */
> + for (i = 0; i < ARRAY_SIZE(qmc_hdlc->rx_descs); i++) {
> + desc = &qmc_hdlc->rx_descs[i];
> +
> + desc->netdev = netdev;
> + ret = qmc_hdlc_recv_queue(qmc_hdlc, desc,
> chan_param.hdlc.max_rx_buf_size);
> + if (ret) {
> + if (ret == -EBUSY && i != 0)
> + break; /* We use all the QMC chan capability */
> + goto free_desc;
> + }
Can be unfolded to
if (ret == -EBUSY && i)
break; /* We use all the QMC chan capability */
if (ret)
goto free_desc;
Easy to read and understand.
> + }
...
> +static int qmc_hdlc_probe(struct platform_device *pdev)
> +{
With
struct device *dev = &pdev->dev;
the below code will be neater (see other comments for the examples).
> + struct device_node *np = pdev->dev.of_node;
It is used only once, drop it (see below).
> + struct qmc_hdlc *qmc_hdlc;
> + struct qmc_chan_info info;
> + hdlc_device *hdlc;
> + int ret;
> +
> + qmc_hdlc = devm_kzalloc(&pdev->dev, sizeof(*qmc_hdlc), GFP_KERNEL);
> + if (!qmc_hdlc)
> + return -ENOMEM;
> +
> + qmc_hdlc->dev = &pdev->dev;
> + spin_lock_init(&qmc_hdlc->tx_lock);
> +
> + qmc_hdlc->qmc_chan = devm_qmc_chan_get_bychild(qmc_hdlc->dev, np);
qmc_hdlc->qmc_chan = devm_qmc_chan_get_bychild(dev, dev->of_node);
> + if (IS_ERR(qmc_hdlc->qmc_chan)) {
> + ret = PTR_ERR(qmc_hdlc->qmc_chan);
> + return dev_err_probe(qmc_hdlc->dev, ret, "get QMC channel
> failed\n");
return dev_err_probe(dev, PTR_ERR(qmc_hdlc->qmc_chan), "get QMC
channel failed\n");
> + }
> +
> + ret = qmc_chan_get_info(qmc_hdlc->qmc_chan, &info);
> + if (ret) {
> + dev_err(qmc_hdlc->dev, "get QMC channel info failed %d\n", ret);
> + return ret;
Why not using same message pattern everywhere, i.e. dev_err_probe()?
return dev_err_probe(dev, ret, "get QMC channel info failed\n");
(and so on...)
> + }
> +
> + if (info.mode != QMC_HDLC) {
> + dev_err(qmc_hdlc->dev, "QMC chan mode %d is not QMC_HDLC\n",
> + info.mode);
> + return -EINVAL;
> + }
> +
> + qmc_hdlc->netdev = alloc_hdlcdev(qmc_hdlc);
> + if (!qmc_hdlc->netdev) {
> + dev_err(qmc_hdlc->dev, "failed to alloc hdlc dev\n");
> + return -ENOMEM;
We do not issue a message for -ENOMEM.
> + }
> +
> + hdlc = dev_to_hdlc(qmc_hdlc->netdev);
> + hdlc->attach = qmc_hdlc_attach;
> + hdlc->xmit = qmc_hdlc_xmit;
> + SET_NETDEV_DEV(qmc_hdlc->netdev, qmc_hdlc->dev);
> + qmc_hdlc->netdev->tx_queue_len = ARRAY_SIZE(qmc_hdlc->tx_descs);
> + qmc_hdlc->netdev->netdev_ops = &qmc_hdlc_netdev_ops;
> + ret = register_hdlc_device(qmc_hdlc->netdev);
> + if (ret) {
> + dev_err(qmc_hdlc->dev, "failed to register hdlc device (%d)\n",
> ret);
> + goto free_netdev;
> + }
> +
> + platform_set_drvdata(pdev, qmc_hdlc);
> +
> + return 0;
> +
> +free_netdev:
> + free_netdev(qmc_hdlc->netdev);
> + return ret;
> +}
--
With Best Regards,
Andy Shevchenko
