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SubjectRe: [PATCH 05/15] usb: serial: cypress_m8: use usb_control_msg_recv() and usb_control_msg_send()
On Wed, Nov 04, 2020 at 12:16:53PM +0530, Himadri Pandya wrote:
> The new usb_control_msg_recv() and usb_control_msg_send() nicely wraps
> usb_control_msg() with proper error check. Hence use the wrappers
> instead of calling usb_control_msg() directly.
>
> Signed-off-by: Himadri Pandya <himadrispandya@gmail.com>
> ---
> drivers/usb/serial/cypress_m8.c | 38 +++++++++++++++++----------------
> 1 file changed, 20 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/usb/serial/cypress_m8.c b/drivers/usb/serial/cypress_m8.c
> index cc028601c388..4d66cab8eece 100644
> --- a/drivers/usb/serial/cypress_m8.c
> +++ b/drivers/usb/serial/cypress_m8.c
> @@ -341,20 +341,21 @@ static int cypress_serial_control(struct tty_struct *tty,
> feature_buffer[4]);
>
> do {
> - retval = usb_control_msg(port->serial->dev,
> - usb_sndctrlpipe(port->serial->dev, 0),
> - HID_REQ_SET_REPORT,
> - USB_DIR_OUT | USB_RECIP_INTERFACE | USB_TYPE_CLASS,
> - 0x0300, 0, feature_buffer,
> - feature_len, 500);
> + retval = usb_control_msg_send(port->serial->dev, 0,
> + HID_REQ_SET_REPORT,
> + USB_DIR_OUT |
> + USB_RECIP_INTERFACE |
> + USB_TYPE_CLASS, 0x0300,
> + 0, feature_buffer,
> + feature_len, 500,
> + GFP_KERNEL);
>
> if (tries++ >= 3)
> break;
>
> - } while (retval != feature_len &&
> - retval != -ENODEV);
> + } while (retval != -ENODEV);

Here you actually break the logic; after this change the driver will
always retry as the test for success is removed.

>
> - if (retval != feature_len) {
> + if (retval) {
> dev_err(dev, "%s - failed sending serial line settings - %d\n",
> __func__, retval);
> cypress_set_dead(port);
> @@ -379,19 +380,20 @@ static int cypress_serial_control(struct tty_struct *tty,
> }
> dev_dbg(dev, "%s - retrieving serial line settings\n", __func__);
> do {
> - retval = usb_control_msg(port->serial->dev,
> - usb_rcvctrlpipe(port->serial->dev, 0),
> - HID_REQ_GET_REPORT,
> - USB_DIR_IN | USB_RECIP_INTERFACE | USB_TYPE_CLASS,
> - 0x0300, 0, feature_buffer,
> - feature_len, 500);
> + retval = usb_control_msg_recv(port->serial->dev, 0,
> + HID_REQ_GET_REPORT,
> + USB_DIR_IN |
> + USB_RECIP_INTERFACE |
> + USB_TYPE_CLASS, 0x0300,
> + 0, feature_buffer,
> + feature_len, 500,
> + GFP_KERNEL);
>
> if (tries++ >= 3)
> break;
> - } while (retval != feature_len
> - && retval != -ENODEV);
> + } while (retval != -ENODEV);

Same here.

>
> - if (retval != feature_len) {
> + if (retval) {
> dev_err(dev, "%s - failed to retrieve serial line settings - %d\n",
> __func__, retval);
> cypress_set_dead(port);

As the driver is already using a DMA-able buffer and is reusing it for
every retry as well, this change is now introducing redundant memdup +
memcpy for each call.

I suggest just dropping this one.

Johan

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