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authorEllen Wang <ellen@cumulusnetworks.com>2015-07-08 20:17:39 +0200
committerJiri Kosina <jkosina@suse.com>2015-07-09 14:15:53 +0200
commit5ddfb12e90c73cf86881345be422e09c367f6981 (patch)
treea8e76a63d4a61f07f34d4f8a1d98a638c340634a /drivers/hid
parentHID: cp2112: fix to force single data-report reply (diff)
downloadlinux-5ddfb12e90c73cf86881345be422e09c367f6981.tar.xz
linux-5ddfb12e90c73cf86881345be422e09c367f6981.zip
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>
Diffstat (limited to 'drivers/hid')
-rw-r--r--drivers/hid/hid-cp2112.c31
1 files changed, 24 insertions, 7 deletions
diff --git a/drivers/hid/hid-cp2112.c b/drivers/hid/hid-cp2112.c
index a2dbbbe0d8d7..75398cb84fde 100644
--- a/drivers/hid/hid-cp2112.c
+++ b/drivers/hid/hid-cp2112.c
@@ -511,13 +511,30 @@ static int cp2112_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
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: