[PATCH v2 05/31] cinergyT2-fe: don't do DMA on stack

[Mauro Carvalho Chehab]

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/cinergyT2-fe.c | 56 +++++++++++++++++++-------------
 1 file changed, 33 insertions(+), 23 deletions(-)

diff --git a/drivers/media/usb/dvb-usb/cinergyT2-fe.c 
b/drivers/media/usb/dvb-usb/cinergyT2-fe.c
index fd8edcb56e61..2d29b4174dba 100644
--- a/drivers/media/usb/dvb-usb/cinergyT2-fe.c
+++ b/drivers/media/usb/dvb-usb/cinergyT2-fe.c
@@ -139,6 +139,10 @@ static uint16_t compute_tps(struct dtv_frontend_properties 
*op)
 struct cinergyt2_fe_state {
        struct dvb_frontend fe;
        struct dvb_usb_device *d;
+
+       unsigned char data[64];
+       struct mutex data_mutex;
+
        struct dvbt_get_status_msg status;
 };
 
@@ -146,28 +150,31 @@ static int cinergyt2_fe_read_status(struct dvb_frontend 
*fe,
                                    enum fe_status *status)
 {
        struct cinergyt2_fe_state *state = fe->demodulator_priv;
-       struct dvbt_get_status_msg result;
-       u8 cmd[] = { CINERGYT2_EP1_GET_TUNER_STATUS };
        int ret;
 
-       ret = dvb_usb_generic_rw(state->d, cmd, sizeof(cmd), (u8 *)&result,
-                       sizeof(result), 0);
+       mutex_lock(&state->data_mutex);
+       state->data[0] = CINERGYT2_EP1_GET_TUNER_STATUS;
+
+       ret = dvb_usb_generic_rw(state->d, state->data, 1,
+                                state->data, sizeof(state->status), 0);
+       if (!ret)
+               memcpy(&state->status, state->data, sizeof(state->status));
+       mutex_unlock(&state->data_mutex);
+
        if (ret < 0)
                return ret;
 
-       state->status = result;
-
        *status = 0;
 
-       if (0xffff - le16_to_cpu(result.gain) > 30)
+       if (0xffff - le16_to_cpu(state->status.gain) > 30)
                *status |= FE_HAS_SIGNAL;
-       if (result.lock_bits & (1 << 6))
+       if (state->status.lock_bits & (1 << 6))
                *status |= FE_HAS_LOCK;
-       if (result.lock_bits & (1 << 5))
+       if (state->status.lock_bits & (1 << 5))
                *status |= FE_HAS_SYNC;
-       if (result.lock_bits & (1 << 4))
+       if (state->status.lock_bits & (1 << 4))
                *status |= FE_HAS_CARRIER;
-       if (result.lock_bits & (1 << 1))
+       if (state->status.lock_bits & (1 << 1))
                *status |= FE_HAS_VITERBI;
 
        if ((*status & (FE_HAS_CARRIER | FE_HAS_VITERBI | FE_HAS_SYNC)) !=
@@ -232,34 +239,36 @@ static int cinergyt2_fe_set_frontend(struct dvb_frontend 
*fe)
 {
        struct dtv_frontend_properties *fep = &fe->dtv_property_cache;
        struct cinergyt2_fe_state *state = fe->demodulator_priv;
-       struct dvbt_set_parameters_msg param;
-       char result[2];
+       struct dvbt_set_parameters_msg *param;
        int err;
 
-       param.cmd = CINERGYT2_EP1_SET_TUNER_PARAMETERS;
-       param.tps = cpu_to_le16(compute_tps(fep));
-       param.freq = cpu_to_le32(fep->frequency / 1000);
-       param.flags = 0;
+       mutex_lock(&state->data_mutex);
+
+       param = (void *)state->data;
+       param->cmd = CINERGYT2_EP1_SET_TUNER_PARAMETERS;
+       param->tps = cpu_to_le16(compute_tps(fep));
+       param->freq = cpu_to_le32(fep->frequency / 1000);
+       param->flags = 0;
 
        switch (fep->bandwidth_hz) {
        default:
        case 8000000:
-               param.bandwidth = 8;
+               param->bandwidth = 8;
                break;
        case 7000000:
-               param.bandwidth = 7;
+               param->bandwidth = 7;
                break;
        case 6000000:
-               param.bandwidth = 6;
+               param->bandwidth = 6;
                break;
        }
 
-       err = dvb_usb_generic_rw(state->d,
-                       (char *)&param, sizeof(param),
-                       result, sizeof(result), 0);
+       err = dvb_usb_generic_rw(state->d, state->data, sizeof(*param),
+                                state->data, 2, 0);
        if (err < 0)
                err("cinergyt2_fe_set_frontend() Failed! err=%d\n", err);
 
+       mutex_unlock(&state->data_mutex);
        return (err < 0) ? err : 0;
 }
 
@@ -281,6 +290,7 @@ struct dvb_frontend *cinergyt2_fe_attach(struct 
dvb_usb_device *d)
        s->d = d;
        memcpy(&s->fe.ops, &cinergyt2_fe_ops, sizeof(struct dvb_frontend_ops));
        s->fe.demodulator_priv = s;
+       mutex_init(&s->data_mutex);
        return &s->fe;
 }
 
-- 
2.7.4


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