Re: [PATCH 20/26] pctv452e: don't do DMA on stack

From: Patrick Boettcher
Date: Mon Oct 10 2016 - 02:35:24 EST

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On Fri, 7 Oct 2016 14:24:30 -0300
Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxxx> wrote:

> 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@xxxxxxxxxxxxxxxx>
> ---
> drivers/media/usb/dvb-usb/pctv452e.c | 110
> ++++++++++++++++++----------------- 1 file changed, 58 insertions(+),
> 52 deletions(-)
>
> diff --git a/drivers/media/usb/dvb-usb/pctv452e.c
> b/drivers/media/usb/dvb-usb/pctv452e.c index
> c05de1b088a4..855fe9d34b59 100644 ---
> a/drivers/media/usb/dvb-usb/pctv452e.c +++
> b/drivers/media/usb/dvb-usb/pctv452e.c @@ -97,13 +97,14 @@ struct
> pctv452e_state { u8 c; /* transaction counter, wraps
> around... */ u8 initialized; /* set to 1 if 0x15 has been sent */
> u16 last_rc_key;
> +
> + unsigned char data[80];
> };
>
> static int tt3650_ci_msg(struct dvb_usb_device *d, u8 cmd, u8 *data,
> unsigned int write_len, unsigned int
> read_len) {
> struct pctv452e_state *state = (struct pctv452e_state
> *)d->priv;
> - u8 buf[64];
> u8 id;
> unsigned int rlen;
> int ret;
> @@ -114,30 +115,30 @@ static int tt3650_ci_msg(struct dvb_usb_device
> *d, u8 cmd, u8 *data,
> id = state->c++;
>
> - buf[0] = SYNC_BYTE_OUT;
> - buf[1] = id;
> - buf[2] = cmd;
> - buf[3] = write_len;
> + state->data[0] = SYNC_BYTE_OUT;
> + state->data[1] = id;
> + state->data[2] = cmd;
> + state->data[3] = write_len;
>
> - memcpy(buf + 4, data, write_len);
> + memcpy(state->data + 4, data, write_len);
>
> rlen = (read_len > 0) ? 64 : 0;
> - ret = dvb_usb_generic_rw(d, buf, 4 + write_len,
> - buf, rlen, /* delay_ms */ 0);
> + ret = dvb_usb_generic_rw(d, state->data, 4 + write_len,
> + state->data, rlen, /* delay_ms */
> 0); if (0 != ret)
> goto failed;
>
> ret = -EIO;
> - if (SYNC_BYTE_IN != buf[0] || id != buf[1])
> + if (SYNC_BYTE_IN != state->data[0] || id != state->data[1])
> goto failed;
>
> - memcpy(data, buf + 4, read_len);
> + memcpy(data, state->data + 4, read_len);
>
> return 0;
>
> failed:
> err("CI error %d; %02X %02X %02X -> %*ph.",
> - ret, SYNC_BYTE_OUT, id, cmd, 3, buf);
> + ret, SYNC_BYTE_OUT, id, cmd, 3, state->data);
>
> return ret;
> }
> @@ -405,7 +406,6 @@ static int pctv452e_i2c_msg(struct dvb_usb_device
> *d, u8 addr, u8 *rcv_buf, u8 rcv_len)
> {
> struct pctv452e_state *state = (struct pctv452e_state
> *)d->priv;
> - u8 buf[64];
> u8 id;
> int ret;
>
> @@ -415,42 +415,40 @@ static int pctv452e_i2c_msg(struct
> dvb_usb_device *d, u8 addr, if (snd_len > 64 - 7 || rcv_len > 64 - 7)
> goto failed;
>
> - buf[0] = SYNC_BYTE_OUT;
> - buf[1] = id;
> - buf[2] = PCTV_CMD_I2C;
> - buf[3] = snd_len + 3;
> - buf[4] = addr << 1;
> - buf[5] = snd_len;
> - buf[6] = rcv_len;
> + state->data[0] = SYNC_BYTE_OUT;
> + state->data[1] = id;
> + state->data[2] = PCTV_CMD_I2C;
> + state->data[3] = snd_len + 3;
> + state->data[4] = addr << 1;
> + state->data[5] = snd_len;
> + state->data[6] = rcv_len;
>
> - memcpy(buf + 7, snd_buf, snd_len);
> + memcpy(state->data + 7, snd_buf, snd_len);
>
> - ret = dvb_usb_generic_rw(d, buf, 7 + snd_len,
> - buf, /* rcv_len */ 64,
> + ret = dvb_usb_generic_rw(d, state->data, 7 + snd_len,
> + state->data, /* rcv_len */ 64,
> /* delay_ms */ 0);
> if (ret < 0)
> goto failed;
>
> /* TT USB protocol error. */
> ret = -EIO;
> - if (SYNC_BYTE_IN != buf[0] || id != buf[1])
> + if (SYNC_BYTE_IN != state->data[0] || id != state->data[1])
> goto failed;
>
> /* I2C device didn't respond as expected. */
> ret = -EREMOTEIO;
> - if (buf[5] < snd_len || buf[6] < rcv_len)
> + if (state->data[5] < snd_len || state->data[6] < rcv_len)
> goto failed;
>
> - memcpy(rcv_buf, buf + 7, rcv_len);
> + memcpy(rcv_buf, state->data + 7, rcv_len);
>
> return rcv_len;
>
> failed:
> - err("I2C error %d; %02X %02X %02X %02X %02X -> "
> - "%02X %02X %02X %02X %02X.",
> + err("I2C error %d; %02X %02X %02X %02X %02X -> %*ph",
> ret, SYNC_BYTE_OUT, id, addr << 1, snd_len, rcv_len,
> - buf[0], buf[1], buf[4], buf[5], buf[6]);
> -
> + 7, state->data);
> return ret;
> }
>
> @@ -499,8 +497,7 @@ static u32 pctv452e_i2c_func(struct i2c_adapter
> *adapter) static int pctv452e_power_ctrl(struct dvb_usb_device *d,
> int i) {
> struct pctv452e_state *state = (struct pctv452e_state
> *)d->priv;
> - u8 b0[] = { 0xaa, 0, PCTV_CMD_RESET, 1, 0 };
> - u8 rx[PCTV_ANSWER_LEN];
> + u8 *rx;
> int ret;
>
> info("%s: %d\n", __func__, i);
> @@ -511,6 +508,10 @@ static int pctv452e_power_ctrl(struct
> dvb_usb_device *d, int i) if (state->initialized)
> return 0;
>
> + rx = kmalloc(PCTV_ANSWER_LEN, GFP_KERNEL);
> + if (!rx)
> + return -ENOMEM;
> +
> /* hmm where shoud this should go? */
> ret = usb_set_interface(d->udev, 0,
> ISOC_INTERFACE_ALTERNATIVE); if (ret != 0)
> @@ -518,57 +519,62 @@ static int pctv452e_power_ctrl(struct
> dvb_usb_device *d, int i) __func__, ret);
>
> /* this is a one-time initialization, dont know where to put
> */
> - b0[1] = state->c++;
> + state->data[0] = 0xaa;
> + state->data[1] = state->c++;
> + state->data[2] = PCTV_CMD_RESET;
> + state->data[3] = 1;
> + state->data[4] = 0;
> /* reset board */
> - ret = dvb_usb_generic_rw(d, b0, sizeof(b0), rx,
> PCTV_ANSWER_LEN, 0);
> + ret = dvb_usb_generic_rw(d, state->data, 5, rx,
> PCTV_ANSWER_LEN, 0); if (ret)
> - return ret;
> + goto ret;
>
> - b0[1] = state->c++;
> - b0[4] = 1;
> + state->data[1] = state->c++;
> + state->data[4] = 1;
> /* reset board (again?) */
> - ret = dvb_usb_generic_rw(d, b0, sizeof(b0), rx,
> PCTV_ANSWER_LEN, 0);
> + ret = dvb_usb_generic_rw(d, state->data, 5, rx,
> PCTV_ANSWER_LEN, 0); if (ret)
> - return ret;
> + goto ret;
>
> state->initialized = 1;
>
> - return 0;
> +ret:
> + kfree(rx);
> + return ret;
> }
>
> static int pctv452e_rc_query(struct dvb_usb_device *d)
> {
> struct pctv452e_state *state = (struct pctv452e_state
> *)d->priv;
> - u8 b[CMD_BUFFER_SIZE];
> - u8 rx[PCTV_ANSWER_LEN];
> int ret, i;
> u8 id = state->c++;
>
> /* prepare command header */
> - b[0] = SYNC_BYTE_OUT;
> - b[1] = id;
> - b[2] = PCTV_CMD_IR;
> - b[3] = 0;
> + state->data[0] = SYNC_BYTE_OUT;
> + state->data[1] = id;
> + state->data[2] = PCTV_CMD_IR;
> + state->data[3] = 0;
>
> /* send ir request */
> - ret = dvb_usb_generic_rw(d, b, 4, rx, PCTV_ANSWER_LEN, 0);
> + ret = dvb_usb_generic_rw(d, state->data, 4,
> + state->data, PCTV_ANSWER_LEN, 0);
> if (ret != 0)
> return ret;
>
> if (debug > 3) {
> - info("%s: read: %2d: %*ph: ", __func__, ret, 3, rx);
> - for (i = 0; (i < rx[3]) && ((i+3) <
> PCTV_ANSWER_LEN); i++)
> - info(" %02x", rx[i+3]);
> + info("%s: read: %2d: %*ph: ", __func__, ret, 3,
> state->data);
> + for (i = 0; (i < state->data[3]) && ((i + 3) <
> PCTV_ANSWER_LEN); i++)
> + info(" %02x", state->data[i + 3]);
>
> info("\n");
> }
>
> - if ((rx[3] == 9) && (rx[12] & 0x01)) {
> + if ((state->data[3] == 9) && (state->data[12] & 0x01)) {
> /* got a "press" event */
> - state->last_rc_key = RC_SCANCODE_RC5(rx[7], rx[6]);
> + state->last_rc_key = RC_SCANCODE_RC5(state->data[7],
> state->data[6]); if (debug > 2)
> info("%s: cmd=0x%02x sys=0x%02x\n",
> - __func__, rx[6], rx[7]);
> + __func__, state->data[6],
> state->data[7]);
> rc_keydown(d->rc_dev, RC_TYPE_RC5,
> state->last_rc_key, 0); } else if (state->last_rc_key) {

Reviewed-By: Patrick Boettcher <patrick.boettcher@xxxxxxxxx>

Next message: Patrick Boettcher: "Re: [PATCH 19/26] nova-t-usb2: don't do DMA on stack"
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