On Thu, Mar 18, 2021 at 01:39:53PM +0300, Dan Carpenter wrote:
>
> drivers/hid/hid-ft260.c
> 1017 static int ft260_raw_event(struct hid_device *hdev, struct hid_report *report,
> 1018 u8 *data, int size)
> 1019 {
> 1020 struct ft260_device *dev = hid_get_drvdata(hdev);
> 1021 struct ft260_i2c_input_report *xfer = (void *)data;
> 1022
> 1023 if (xfer->report >= FT260_I2C_REPORT_MIN &&
> 1024 xfer->report <= FT260_I2C_REPORT_MAX) {
> 1025 ft260_dbg("i2c resp: rep %#02x len %d\n", xfer->report,
> 1026 xfer->length);
> 1027
> 1028 memcpy(&dev->read_buf[dev->read_idx], &xfer->data,
> 1029 xfer->length);
>
> Do we need to check if "xfer->len <= dev->read_len"?
The dev->read_len is a total length to be read, passed into ft260_i2c_read()
by a user. This length is divided into 60 bytes chanks to be retrieved from
the ft260 controller. The ft260_raw_event() receives these chanks and counts
the total number of bytes received in read_idx. Once it matches the read_len,
we conclude on the i2c read transfer completion. We do not need to check the
xfer->len against the dev->read_len since the ft260 controller never returns
more bytes than was asked to read.
>
> 1030 dev->read_idx += xfer->length;
> 1031
> 1032 if (dev->read_idx == dev->read_len)
> 1033 complete(&dev->wait);
> 1034
> 1035 } else {
> 1036 hid_err(hdev, "unknown report: %#02x\n", xfer->report);
> 1037 return 0;
> 1038 }
> 1039 return 1;
> 1040 }
>
> regards,
> dan carpenter
