Re: [PATCH v3 1/7] mfd: Add core driver for Nuvoton NCT6694

[Ming Yu <a0282524688@xxxxxxxxx>]

Dear Christophe,

Thank you for your comments,

Christophe JAILLET <christophe.jaillet@xxxxxxxxxx> 於 2024年12月12日 週四 上午12:44寫道：
>
> > +int nct6694_read_msg(struct nct6694 *nct6694, u8 mod, u16 offset,
> > +                  u16 length, void *buf)
> > +{
> > +     struct nct6694_cmd_header *cmd_header = nct6694->cmd_header;
> > +     struct nct6694_response_header *response_header = nct6694->response_header;
> > +     struct usb_device *udev = nct6694->udev;
> > +     int tx_len, rx_len, ret;
> > +
> > +     guard(mutex)(&nct6694->access_lock);
>
> Nitpick: This could be moved a few lines below, should it still comply
> with your coding style.
>

I think the lock should be placed here to prevent the cmd_header from
being overwritten by another caller.
Could you share your perspective on this?

> > +
> > +     /* Send command packet to USB device */
> > +     cmd_header->mod = mod;
> > +     cmd_header->cmd = offset & 0xFF;
> > +     cmd_header->sel = (offset >> 8) & 0xFF;
> > +     cmd_header->hctrl = NCT6694_HCTRL_GET;
> > +     cmd_header->len = length;
> > +
> > +     ret = usb_bulk_msg(udev, usb_sndbulkpipe(udev, NCT6694_BULK_OUT_EP),
> > +                        cmd_header, NCT6694_CMD_PACKET_SZ, &tx_len,
> > +                        nct6694->timeout);
> > +     if (ret)
> > +             return ret;
> > +
> > +     /* Receive response packet from USB device */
> > +     ret = usb_bulk_msg(udev, usb_rcvbulkpipe(udev, NCT6694_BULK_IN_EP),
> > +                        response_header, NCT6694_CMD_PACKET_SZ, &rx_len,
> > +                        nct6694->timeout);
> > +     if (ret)
> > +             return ret;
> > +
> > +     ret = usb_bulk_msg(udev, usb_rcvbulkpipe(udev, NCT6694_BULK_IN_EP),
> > +                        buf, NCT6694_MAX_PACKET_SZ, &rx_len, nct6694->timeout);
> > +     if (ret)
> > +             return ret;
> > +
> > +     return nct6694_response_err_handling(nct6694, response_header->sts);
> > +}
> > +EXPORT_SYMBOL(nct6694_read_msg);
> > +
> > +int nct6694_write_msg(struct nct6694 *nct6694, u8 mod, u16 offset,
> > +                   u16 length, void *buf)
> > +{
> > +     struct nct6694_cmd_header *cmd_header = nct6694->cmd_header;
> > +     struct nct6694_response_header *response_header = nct6694->response_header;
> > +     struct usb_device *udev = nct6694->udev;
> > +     int tx_len, rx_len, ret;
> > +
> > +     guard(mutex)(&nct6694->access_lock);
>
> Nitpick: This could be moved a few lines below, should it still comply
> with your coding style.
>

I think the lock should be placed here to prevent the cmd_header from
being overwritten by another caller.
Could you share your perspective on this?

> > +
> > +     /* Send command packet to USB device  */
>
> Nitpick: double space before */
>

Fix it in v4.

> > +     cmd_header->mod = mod;
> > +     cmd_header->cmd = offset & 0xFF;
> > +     cmd_header->sel = (offset >> 8) & 0xFF;
> > +     cmd_header->hctrl = NCT6694_HCTRL_SET;
> > +     cmd_header->len = length;
>
> ...
>
> > +static struct irq_chip nct6694_irq_chip = {
>
> const?
>

Fix it in v4.

> > +     .name = "nct6694-irq",
> > +     .flags = IRQCHIP_SKIP_SET_WAKE,
> > +     .irq_bus_lock = nct6694_irq_lock,
> > +     .irq_bus_sync_unlock = nct6694_irq_sync_unlock,
> > +     .irq_enable = nct6694_irq_enable,
> > +     .irq_disable = nct6694_irq_disable,
> > +};
>
> ...
>
> > +static int nct6694_usb_probe(struct usb_interface *iface,
> > +                          const struct usb_device_id *id)
> > +{
> > +     struct usb_device *udev = interface_to_usbdev(iface);
> > +     struct device *dev = &udev->dev;
> > +     struct usb_host_interface *interface;
> > +     struct usb_endpoint_descriptor *int_endpoint;
> > +     struct nct6694 *nct6694;
> > +     struct nct6694_cmd_header *cmd_header;
> > +     struct nct6694_response_header *response_header;
> > +     int pipe, maxp;
> > +     int ret;
> > +
> > +     interface = iface->cur_altsetting;
> > +
> > +     int_endpoint = &interface->endpoint[0].desc;
> > +     if (!usb_endpoint_is_int_in(int_endpoint))
> > +             return -ENODEV;
> > +
> > +     nct6694 = devm_kzalloc(dev, sizeof(*nct6694), GFP_KERNEL);
> > +     if (!nct6694)
> > +             return -ENOMEM;
> > +
> > +     pipe = usb_rcvintpipe(udev, NCT6694_INT_IN_EP);
> > +     maxp = usb_maxpacket(udev, pipe);
> > +
> > +     cmd_header = devm_kzalloc(dev, sizeof(*cmd_header),
> > +                               GFP_KERNEL);
> > +     if (!cmd_header)
> > +             return -ENOMEM;
> > +
> > +     response_header = devm_kzalloc(dev, sizeof(*response_header),
> > +                                    GFP_KERNEL);
> > +     if (!response_header)
> > +             return -ENOMEM;
> > +
> > +     nct6694->int_buffer = devm_kcalloc(dev, NCT6694_MAX_PACKET_SZ,
> > +                                        sizeof(unsigned char), GFP_KERNEL);
>
> Why for cmd_header and response_header we use a temp variable, while
> here we update directly nct6694->int_buffer?
>
> It would save a few LoC do remove this temp var.
>

Fix it in v4.

> > +     if (!nct6694->int_buffer)
> > +             return -ENOMEM;
> > +
> > +     nct6694->int_in_urb = usb_alloc_urb(0, GFP_KERNEL);
> > +     if (!nct6694->int_in_urb)
> > +             return -ENOMEM;
>
> ...
>

Best regards,
Ming