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    Subject[PATCH v2 13/31] dtt200u-fe: don't do DMA on stack
    Date
    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.

    Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
    ---
    drivers/media/usb/dvb-usb/dtt200u-fe.c | 95 +++++++++++++++++++++++-----------
    1 file changed, 65 insertions(+), 30 deletions(-)

    diff --git a/drivers/media/usb/dvb-usb/dtt200u-fe.c b/drivers/media/usb/dvb-usb/dtt200u-fe.c
    index 9bb15f7b48db..7f7f64be6353 100644
    --- a/drivers/media/usb/dvb-usb/dtt200u-fe.c
    +++ b/drivers/media/usb/dvb-usb/dtt200u-fe.c
    @@ -18,17 +18,22 @@ struct dtt200u_fe_state {

    struct dtv_frontend_properties fep;
    struct dvb_frontend frontend;
    +
    + unsigned char data[80];
    + struct mutex data_mutex;
    };

    static int dtt200u_fe_read_status(struct dvb_frontend *fe,
    enum fe_status *stat)
    {
    struct dtt200u_fe_state *state = fe->demodulator_priv;
    - u8 st = GET_TUNE_STATUS, b[3];

    - dvb_usb_generic_rw(state->d,&st,1,b,3,0);
    + mutex_lock(&state->data_mutex);
    + state->data[0] = GET_TUNE_STATUS;

    - switch (b[0]) {
    + dvb_usb_generic_rw(state->d, state->data, 1, state->data, 3, 0);
    +
    + switch (state->data[0]) {
    case 0x01:
    *stat = FE_HAS_SIGNAL | FE_HAS_CARRIER |
    FE_HAS_VITERBI | FE_HAS_SYNC | FE_HAS_LOCK;
    @@ -41,51 +46,75 @@ static int dtt200u_fe_read_status(struct dvb_frontend *fe,
    *stat = 0;
    break;
    }
    + mutex_unlock(&state->data_mutex);
    return 0;
    }

    static int dtt200u_fe_read_ber(struct dvb_frontend* fe, u32 *ber)
    {
    struct dtt200u_fe_state *state = fe->demodulator_priv;
    - u8 bw = GET_VIT_ERR_CNT,b[3];
    - dvb_usb_generic_rw(state->d,&bw,1,b,3,0);
    - *ber = (b[0] << 16) | (b[1] << 8) | b[2];
    +
    + mutex_lock(&state->data_mutex);
    + state->data[0] = GET_VIT_ERR_CNT;
    +
    + dvb_usb_generic_rw(state->d, state->data, 1, state->data, 3, 0);
    + *ber = (state->data[0] << 16) | (state->data[1] << 8) | state->data[2];
    +
    + mutex_unlock(&state->data_mutex);
    return 0;
    }

    static int dtt200u_fe_read_unc_blocks(struct dvb_frontend* fe, u32 *unc)
    {
    struct dtt200u_fe_state *state = fe->demodulator_priv;
    - u8 bw = GET_RS_UNCOR_BLK_CNT,b[2];

    - dvb_usb_generic_rw(state->d,&bw,1,b,2,0);
    - *unc = (b[0] << 8) | b[1];
    - return 0;
    + mutex_lock(&state->data_mutex);
    + state->data[0] = GET_RS_UNCOR_BLK_CNT;
    +
    + dvb_usb_generic_rw(state->d, state->data, 1, state->data, 2, 0);
    +
    + mutex_unlock(&state->data_mutex);
    + return ret;
    }

    static int dtt200u_fe_read_signal_strength(struct dvb_frontend* fe, u16 *strength)
    {
    struct dtt200u_fe_state *state = fe->demodulator_priv;
    - u8 bw = GET_AGC, b;
    - dvb_usb_generic_rw(state->d,&bw,1,&b,1,0);
    - *strength = (b << 8) | b;
    - return 0;
    +
    + mutex_lock(&state->data_mutex);
    + state->data[0] = GET_AGC;
    +
    + dvb_usb_generic_rw(state->d, state->data, 1, state->data, 1, 0);
    +
    + mutex_unlock(&state->data_mutex);
    + return ret;
    }

    static int dtt200u_fe_read_snr(struct dvb_frontend* fe, u16 *snr)
    {
    struct dtt200u_fe_state *state = fe->demodulator_priv;
    - u8 bw = GET_SNR,br;
    - dvb_usb_generic_rw(state->d,&bw,1,&br,1,0);
    - *snr = ~((br << 8) | br);
    - return 0;
    +
    + mutex_lock(&state->data_mutex);
    + state->data[0] = GET_SNR;
    +
    + dvb_usb_generic_rw(state->d, state->data, 1, state->data, 1, 0);
    +
    + mutex_unlock(&state->data_mutex);
    + return ret;
    }

    static int dtt200u_fe_init(struct dvb_frontend* fe)
    {
    struct dtt200u_fe_state *state = fe->demodulator_priv;
    - u8 b = SET_INIT;
    - return dvb_usb_generic_write(state->d,&b,1);
    + int ret;
    +
    + mutex_lock(&state->data_mutex);
    + state->data[0] = SET_INIT;
    +
    + ret = dvb_usb_generic_write(state->d, state->data, 1);
    + mutex_unlock(&state->data_mutex);
    +
    + return ret;
    }

    static int dtt200u_fe_sleep(struct dvb_frontend* fe)
    @@ -106,29 +135,34 @@ static int dtt200u_fe_set_frontend(struct dvb_frontend *fe)
    struct dtv_frontend_properties *fep = &fe->dtv_property_cache;
    struct dtt200u_fe_state *state = fe->demodulator_priv;
    u16 freq = fep->frequency / 250000;
    - u8 bwbuf[2] = { SET_BANDWIDTH, 0 },freqbuf[3] = { SET_RF_FREQ, 0, 0 };

    + mutex_lock(&state->data_mutex);
    + state->data[0] = SET_BANDWIDTH;
    switch (fep->bandwidth_hz) {
    case 8000000:
    - bwbuf[1] = 8;
    + state->data[1] = 8;
    break;
    case 7000000:
    - bwbuf[1] = 7;
    + state->data[1] = 7;
    break;
    case 6000000:
    - bwbuf[1] = 6;
    + state->data[1] = 6;
    break;
    default:
    - return -EINVAL;
    + ret = -EINVAL;
    + goto ret;
    }

    - dvb_usb_generic_write(state->d,bwbuf,2);
    + dvb_usb_generic_write(state->d, state->data, 2);

    - freqbuf[1] = freq & 0xff;
    - freqbuf[2] = (freq >> 8) & 0xff;
    - dvb_usb_generic_write(state->d,freqbuf,3);
    + state->data[0] = SET_RF_FREQ;
    + state->data[1] = freq & 0xff;
    + state->data[2] = (freq >> 8) & 0xff;
    + dvb_usb_generic_write(state->d, state->data, 3);

    - return 0;
    +ret:
    + mutex_unlock(&state->data_mutex);
    + return ret;
    }

    static int dtt200u_fe_get_frontend(struct dvb_frontend* fe,
    @@ -160,6 +194,7 @@ struct dvb_frontend* dtt200u_fe_attach(struct dvb_usb_device *d)
    deb_info("attaching frontend dtt200u\n");

    state->d = d;
    + mutex_init(&state->data_mutex);

    memcpy(&state->frontend.ops,&dtt200u_fe_ops,sizeof(struct dvb_frontend_ops));
    state->frontend.demodulator_priv = state;
    --
    2.7.4

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