The USB control messages require DMA to work. We cannot pass
a stack-allocated buffer, as it is not warranted that the
stack would be into a DMA enabled area.

Reviewed-By: Patrick Boettcher <patrick.boettc...@posteo.de>
Signed-off-by: Mauro Carvalho Chehab <mche...@s-opensource.com>
---
 drivers/media/usb/dvb-usb/cxusb.c | 62 ++++++++++++++++++++++-----------------
 drivers/media/usb/dvb-usb/cxusb.h |  6 ++++
 2 files changed, 41 insertions(+), 27 deletions(-)

diff --git a/drivers/media/usb/dvb-usb/cxusb.c 
b/drivers/media/usb/dvb-usb/cxusb.c
index 907ac01ae297..39772812269d 100644
--- a/drivers/media/usb/dvb-usb/cxusb.c
+++ b/drivers/media/usb/dvb-usb/cxusb.c
@@ -45,9 +45,6 @@
 #include "si2168.h"
 #include "si2157.h"
 
-/* Max transfer size done by I2C transfer functions */
-#define MAX_XFER_SIZE  80
-
 /* debug */
 static int dvb_usb_cxusb_debug;
 module_param_named(debug, dvb_usb_cxusb_debug, int, 0644);
@@ -61,23 +58,27 @@ DVB_DEFINE_MOD_OPT_ADAPTER_NR(adapter_nr);
 static int cxusb_ctrl_msg(struct dvb_usb_device *d,
                          u8 cmd, u8 *wbuf, int wlen, u8 *rbuf, int rlen)
 {
-       int wo = (rbuf == NULL || rlen == 0); /* write-only */
-       u8 sndbuf[MAX_XFER_SIZE];
+       struct cxusb_state *st = d->priv;
+       int ret, wo;
 
-       if (1 + wlen > sizeof(sndbuf)) {
-               warn("i2c wr: len=%d is too big!\n",
-                    wlen);
+       if (1 + wlen > MAX_XFER_SIZE) {
+               warn("i2c wr: len=%d is too big!\n", wlen);
                return -EOPNOTSUPP;
        }
 
-       memset(sndbuf, 0, 1+wlen);
+       wo = (rbuf == NULL || rlen == 0); /* write-only */
 
-       sndbuf[0] = cmd;
-       memcpy(&sndbuf[1], wbuf, wlen);
+       mutex_lock(&st->data_mutex);
+       st->data[0] = cmd;
+       memcpy(&st->data[1], wbuf, wlen);
        if (wo)
-               return dvb_usb_generic_write(d, sndbuf, 1+wlen);
+               ret = dvb_usb_generic_write(d, st->data, 1 + wlen);
        else
-               return dvb_usb_generic_rw(d, sndbuf, 1+wlen, rbuf, rlen, 0);
+               ret = dvb_usb_generic_rw(d, st->data, 1 + wlen,
+                                        rbuf, rlen, 0);
+
+       mutex_unlock(&st->data_mutex);
+       return ret;
 }
 
 /* GPIO */
@@ -1460,36 +1461,43 @@ static struct dvb_usb_device_properties 
cxusb_mygica_t230_properties;
 static int cxusb_probe(struct usb_interface *intf,
                       const struct usb_device_id *id)
 {
+       struct dvb_usb_device *d;
+       struct cxusb_state *st;
+
        if (0 == dvb_usb_device_init(intf, &cxusb_medion_properties,
-                                    THIS_MODULE, NULL, adapter_nr) ||
+                                    THIS_MODULE, &d, adapter_nr) ||
            0 == dvb_usb_device_init(intf, &cxusb_bluebird_lgh064f_properties,
-                                    THIS_MODULE, NULL, adapter_nr) ||
+                                    THIS_MODULE, &d, adapter_nr) ||
            0 == dvb_usb_device_init(intf, &cxusb_bluebird_dee1601_properties,
-                                    THIS_MODULE, NULL, adapter_nr) ||
+                                    THIS_MODULE, &d, adapter_nr) ||
            0 == dvb_usb_device_init(intf, &cxusb_bluebird_lgz201_properties,
-                                    THIS_MODULE, NULL, adapter_nr) ||
+                                    THIS_MODULE, &d, adapter_nr) ||
            0 == dvb_usb_device_init(intf, &cxusb_bluebird_dtt7579_properties,
-                                    THIS_MODULE, NULL, adapter_nr) ||
+                                    THIS_MODULE, &d, adapter_nr) ||
            0 == dvb_usb_device_init(intf, &cxusb_bluebird_dualdig4_properties,
-                                    THIS_MODULE, NULL, adapter_nr) ||
+                                    THIS_MODULE, &d, adapter_nr) ||
            0 == dvb_usb_device_init(intf, &cxusb_bluebird_nano2_properties,
-                                    THIS_MODULE, NULL, adapter_nr) ||
+                                    THIS_MODULE, &d, adapter_nr) ||
            0 == dvb_usb_device_init(intf,
                                &cxusb_bluebird_nano2_needsfirmware_properties,
-                                    THIS_MODULE, NULL, adapter_nr) ||
+                                    THIS_MODULE, &d, adapter_nr) ||
            0 == dvb_usb_device_init(intf, &cxusb_aver_a868r_properties,
-                                    THIS_MODULE, NULL, adapter_nr) ||
+                                    THIS_MODULE, &d, adapter_nr) ||
            0 == dvb_usb_device_init(intf,
                                     &cxusb_bluebird_dualdig4_rev2_properties,
-                                    THIS_MODULE, NULL, adapter_nr) ||
+                                    THIS_MODULE, &d, adapter_nr) ||
            0 == dvb_usb_device_init(intf, &cxusb_d680_dmb_properties,
-                                    THIS_MODULE, NULL, adapter_nr) ||
+                                    THIS_MODULE, &d, adapter_nr) ||
            0 == dvb_usb_device_init(intf, &cxusb_mygica_d689_properties,
-                                    THIS_MODULE, NULL, adapter_nr) ||
+                                    THIS_MODULE, &d, adapter_nr) ||
            0 == dvb_usb_device_init(intf, &cxusb_mygica_t230_properties,
-                                    THIS_MODULE, NULL, adapter_nr) ||
-           0)
+                                    THIS_MODULE, &d, adapter_nr) ||
+           0) {
+               st = d->priv;
+               mutex_init(&st->data_mutex);
+
                return 0;
+       }
 
        return -EINVAL;
 }
diff --git a/drivers/media/usb/dvb-usb/cxusb.h 
b/drivers/media/usb/dvb-usb/cxusb.h
index 527ff7905e15..9f3ee0e47d5c 100644
--- a/drivers/media/usb/dvb-usb/cxusb.h
+++ b/drivers/media/usb/dvb-usb/cxusb.h
@@ -28,10 +28,16 @@
 #define CMD_ANALOG        0x50
 #define CMD_DIGITAL       0x51
 
+/* Max transfer size done by I2C transfer functions */
+#define MAX_XFER_SIZE  80
+
 struct cxusb_state {
        u8 gpio_write_state[3];
        struct i2c_client *i2c_client_demod;
        struct i2c_client *i2c_client_tuner;
+
+       unsigned char data[MAX_XFER_SIZE];
+       struct mutex data_mutex;
 };
 
 #endif
-- 
2.7.4


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