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

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Em Thu, 6 Oct 2016 10:27:56 -0700
Andy Lutomirski <luto@xxxxxxxxxxxxxx> escreveu:

> On Wed, Oct 5, 2016 at 11:58 AM, Mauro Carvalho Chehab
> <mchehab@xxxxxxxxxxxxxxxx> wrote:
> > Sorry, forgot to C/C people that are at the "Re: Problem with VMAP_STACK=y"
> > thread.
> >
> > Forwarded message:
> >
> > Date: Wed,  5 Oct 2016 15:54:18 -0300
> > From: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxxx>
> > To: Linux Doc Mailing List <linux-doc@xxxxxxxxxxxxxxx>
> > Cc: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxxx>, Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxx>, Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
> > Subject: [PATCH v2] cinergyT2-core: don't do DMA on stack
> >
> >
> > 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>
> > ---
> >
> > 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)
> >  {  
> 
> This...
> 
> > -       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;  
> 
> ...does not match this:
> 
> > +       st->data[1] = enable ? 1 : 0;  
> 
> --Andy

Gah! Yes. This is what happens when coding using cut-and-paste ;)

Jörg,

Please test it with the condition reversed with the enclosed patch.

if this doesn't work, you can enable dvb-usb debug at runtime,
by loading it with debug parameter:

parm:           debug:set debugging level (1=info,xfer=2,pll=4,ts=8,err=16,rc=32,fw=64,mem=128,uxfer=256  (or-able)). (debugging is not enabled) (int)

debug=2 should show the control messages sent to the device on dmesg.

Regards,
Mauro


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

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>

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;
 }



Thanks,
Mauro
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