Re: [PATCH 02/26] cinergyT2-core: don't do DMA on stack

From: Patrick Boettcher
Date: Mon Oct 10 2016 - 02:39:58 EST


On Fri, 7 Oct 2016 14:24:12 -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/cinergyT2-core.c | 45
> ++++++++++++++++++------------ 1 file changed, 27 insertions(+), 18
> deletions(-)
>
> diff --git a/drivers/media/usb/dvb-usb/cinergyT2-core.c
> b/drivers/media/usb/dvb-usb/cinergyT2-core.c index
> 9fd1527494eb..91640c927776 100644 ---
> a/drivers/media/usb/dvb-usb/cinergyT2-core.c +++
> b/drivers/media/usb/dvb-usb/cinergyT2-core.c @@ -41,6 +41,7 @@
> DVB_DEFINE_MOD_OPT_ADAPTER_NR(adapter_nr);
> struct cinergyt2_state {
> u8 rc_counter;
> + unsigned char data[64];
> };
>
> /* We are missing a release hook with usb_device data */
> @@ -50,29 +51,36 @@ static struct dvb_usb_device_properties
> cinergyt2_properties;
> static int cinergyt2_streaming_ctrl(struct dvb_usb_adapter *adap,
> int enable) {
> - char buf[] = { CINERGYT2_EP1_CONTROL_STREAM_TRANSFER,
> enable ? 1 : 0 };
> - char result[64];
> - return dvb_usb_generic_rw(adap->dev, buf, sizeof(buf),
> result,
> - sizeof(result), 0);
> + struct dvb_usb_device *d = adap->dev;
> + struct cinergyt2_state *st = d->priv;
> +
> + st->data[0] = CINERGYT2_EP1_CONTROL_STREAM_TRANSFER;
> + st->data[1] = enable ? 1 : 0;
> +
> + return dvb_usb_generic_rw(d, st->data, 2, st->data, 64, 0);
> }
>
> static int cinergyt2_power_ctrl(struct dvb_usb_device *d, int enable)
> {
> - char buf[] = { CINERGYT2_EP1_SLEEP_MODE, enable ? 0 : 1 };
> - char state[3];
> - return dvb_usb_generic_rw(d, buf, sizeof(buf), state,
> sizeof(state), 0);
> + struct cinergyt2_state *st = d->priv;
> +
> + st->data[0] = CINERGYT2_EP1_SLEEP_MODE;
> + st->data[1] = enable ? 0 : 1;
> +
> + return dvb_usb_generic_rw(d, st->data, 2, st->data, 3, 0);
> }
>
> static int cinergyt2_frontend_attach(struct dvb_usb_adapter *adap)
> {
> - char query[] = { CINERGYT2_EP1_GET_FIRMWARE_VERSION };
> - char state[3];
> + struct dvb_usb_device *d = adap->dev;
> + struct cinergyt2_state *st = d->priv;
> int ret;
>
> adap->fe_adap[0].fe = cinergyt2_fe_attach(adap->dev);
>
> - ret = dvb_usb_generic_rw(adap->dev, query, sizeof(query),
> state,
> - sizeof(state), 0);
> + st->data[0] = CINERGYT2_EP1_GET_FIRMWARE_VERSION;
> +
> + ret = dvb_usb_generic_rw(d, st->data, 1, st->data, 3, 0);
> if (ret < 0) {
> deb_rc("cinergyt2_power_ctrl() Failed to retrieve
> sleep " "state info\n");
> @@ -141,13 +149,14 @@ static int repeatable_keys[] = {
> static int cinergyt2_rc_query(struct dvb_usb_device *d, u32 *event,
> int *state) {
> struct cinergyt2_state *st = d->priv;
> - u8 key[5] = {0, 0, 0, 0, 0}, cmd =
> CINERGYT2_EP1_GET_RC_EVENTS; int i;
>
> *state = REMOTE_NO_KEY_PRESSED;
>
> - dvb_usb_generic_rw(d, &cmd, 1, key, sizeof(key), 0);
> - if (key[4] == 0xff) {
> + st->data[0] = CINERGYT2_EP1_GET_RC_EVENTS;
> +
> + dvb_usb_generic_rw(d, st->data, 1, st->data, 5, 0);
> + if (st->data[4] == 0xff) {
> /* key repeat */
> st->rc_counter++;
> if (st->rc_counter > RC_REPEAT_DELAY) {
> @@ -166,13 +175,13 @@ static int cinergyt2_rc_query(struct
> dvb_usb_device *d, u32 *event, int *state) }
>
> /* hack to pass checksum on the custom field */
> - key[2] = ~key[1];
> - dvb_usb_nec_rc_key_to_event(d, key, event, state);
> - if (key[0] != 0) {
> + st->data[2] = ~st->data[1];
> + dvb_usb_nec_rc_key_to_event(d, st->data, event, state);
> + if (st->data[0] != 0) {
> if (*event != d->last_event)
> st->rc_counter = 0;
>
> - deb_rc("key: %*ph\n", 5, key);
> + deb_rc("key: %*ph\n", 5, st->data);
> }
> return 0;
> }

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