HID: cp2112: support large i2c transfers
cp2112_i2c_xfer() only reads up to 61 bytes, returning EIO on longers reads.
The fix is to wrap a loop around cp2112_read() to pick up all the returned
data.
Signed-off-by: Ellen Wang <ellen@cumulusnetworks.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>
diff --git a/drivers/hid/hid-cp2112.c b/drivers/hid/hid-cp2112.c
index a2dbbbe..75398cb 100644
--- a/drivers/hid/hid-cp2112.c
+++ b/drivers/hid/hid-cp2112.c
@@ -511,13 +511,30 @@
if (!(msgs->flags & I2C_M_RD))
goto finish;
- ret = cp2112_read(dev, msgs->buf, msgs->len);
- if (ret < 0)
- goto power_normal;
- if (ret != msgs->len) {
- hid_warn(hdev, "short read: %d < %d\n", ret, msgs->len);
- ret = -EIO;
- goto power_normal;
+ for (count = 0; count < msgs->len;) {
+ ret = cp2112_read(dev, msgs->buf + count, msgs->len - count);
+ if (ret < 0)
+ goto power_normal;
+ if (ret == 0) {
+ hid_err(hdev, "read returned 0\n");
+ ret = -EIO;
+ goto power_normal;
+ }
+ count += ret;
+ if (count > msgs->len) {
+ /*
+ * The hardware returned too much data.
+ * This is mostly harmless because cp2112_read()
+ * has a limit check so didn't overrun our
+ * buffer. Nevertheless, we return an error
+ * because something is seriously wrong and
+ * it shouldn't go unnoticed.
+ */
+ hid_err(hdev, "long read: %d > %zd\n",
+ ret, msgs->len - count + ret);
+ ret = -EIO;
+ goto power_normal;
+ }
}
finish: