Re: [PATCH v2] cinergyT2-core: don't do DMA on stack

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Em Wed,  5 Oct 2016 15:54:18 -0300
Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxxx> escreveu:

> 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.

Please disregard this patch at linux-doc ML. It was sent to the wrong
list by mistake.

Regards,
Mauro

> 
> Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxxx>
> ---
> 
> Added the fixups made by Johannes Stezenbach
> 
>  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..8267e3777af6 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 ? 1 : 0;
> +
> +	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;
>  }



Thanks,
Mauro
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