Re: [PATCH 11/26] digitv: don't do DMA on stack

[Patrick Boettcher]

On Fri,  7 Oct 2016 14:24:21 -0300
Mauro Carvalho Chehab  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 
> ---
>  drivers/media/usb/dvb-usb/digitv.c | 20 +++-
>  drivers/media/usb/dvb-usb/digitv.h |  3 +++
>  2 files changed, 14 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/media/usb/dvb-usb/digitv.c
> b/drivers/media/usb/dvb-usb/digitv.c index 63134335c994..09f8c28bd4db
> 100644 --- a/drivers/media/usb/dvb-usb/digitv.c
> +++ b/drivers/media/usb/dvb-usb/digitv.c
> @@ -28,20 +28,22 @@ DVB_DEFINE_MOD_OPT_ADAPTER_NR(adapter_nr);
>  static int digitv_ctrl_msg(struct dvb_usb_device *d,
>   u8 cmd, u8 vv, u8 *wbuf, int wlen, u8 *rbuf, int
> rlen) {
> + struct digitv_state *st = d->priv;
>   int wo = (rbuf == NULL || rlen == 0); /* write-only */
> - u8 sndbuf[7],rcvbuf[7];
> - memset(sndbuf,0,7); memset(rcvbuf,0,7);
>  
> - sndbuf[0] = cmd;
> - sndbuf[1] = vv;
> - sndbuf[2] = wo ? wlen : rlen;
> + memset(st->sndbuf, 0, 7);
> + memset(st->rcvbuf, 0, 7);
> +
> + st->sndbuf[0] = cmd;
> + st->sndbuf[1] = vv;
> + st->sndbuf[2] = wo ? wlen : rlen;
>  
>   if (wo) {
> - memcpy([3],wbuf,wlen);
> - dvb_usb_generic_write(d,sndbuf,7);
> + memcpy(>sndbuf[3], wbuf, wlen);
> + dvb_usb_generic_write(d, st->sndbuf, 7);
>   } else {
> - dvb_usb_generic_rw(d,sndbuf,7,rcvbuf,7,10);
> - memcpy(rbuf,[3],rlen);
> + dvb_usb_generic_rw(d, st->sndbuf, 7, st->rcvbuf, 7,
> 10);
> + memcpy(rbuf, >rcvbuf[3], rlen);
>   }
>   return 0;
>  }
> diff --git a/drivers/media/usb/dvb-usb/digitv.h
> b/drivers/media/usb/dvb-usb/digitv.h index 908c09f4966b..cf104689bdff
> 100644 --- a/drivers/media/usb/dvb-usb/digitv.h
> +++ b/drivers/media/usb/dvb-usb/digitv.h
> @@ -6,6 +6,9 @@
>  
>  struct digitv_state {
>  int is_nxt6000;
> +
> +unsigned char sndbuf[7];
> +unsigned char rcvbuf[7];
>  };
>  
>  /* protocol (from usblogging and the SDK:

Reviewed-By: Patrick Boettcher 
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[PATCH 11/26] digitv: don't do DMA on stack

[Mauro Carvalho Chehab]

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 
---
 drivers/media/usb/dvb-usb/digitv.c | 20 +++-
 drivers/media/usb/dvb-usb/digitv.h |  3 +++
 2 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/drivers/media/usb/dvb-usb/digitv.c 
b/drivers/media/usb/dvb-usb/digitv.c
index 63134335c994..09f8c28bd4db 100644
--- a/drivers/media/usb/dvb-usb/digitv.c
+++ b/drivers/media/usb/dvb-usb/digitv.c
@@ -28,20 +28,22 @@ DVB_DEFINE_MOD_OPT_ADAPTER_NR(adapter_nr);
 static int digitv_ctrl_msg(struct dvb_usb_device *d,
u8 cmd, u8 vv, u8 *wbuf, int wlen, u8 *rbuf, int rlen)
 {
+   struct digitv_state *st = d->priv;
int wo = (rbuf == NULL || rlen == 0); /* write-only */
-   u8 sndbuf[7],rcvbuf[7];
-   memset(sndbuf,0,7); memset(rcvbuf,0,7);
 
-   sndbuf[0] = cmd;
-   sndbuf[1] = vv;
-   sndbuf[2] = wo ? wlen : rlen;
+   memset(st->sndbuf, 0, 7);
+   memset(st->rcvbuf, 0, 7);
+
+   st->sndbuf[0] = cmd;
+   st->sndbuf[1] = vv;
+   st->sndbuf[2] = wo ? wlen : rlen;
 
if (wo) {
-   memcpy([3],wbuf,wlen);
-   dvb_usb_generic_write(d,sndbuf,7);
+   memcpy(>sndbuf[3], wbuf, wlen);
+   dvb_usb_generic_write(d, st->sndbuf, 7);
} else {
-   dvb_usb_generic_rw(d,sndbuf,7,rcvbuf,7,10);
-   memcpy(rbuf,[3],rlen);
+   dvb_usb_generic_rw(d, st->sndbuf, 7, st->rcvbuf, 7, 10);
+   memcpy(rbuf, >rcvbuf[3], rlen);
}
return 0;
 }
diff --git a/drivers/media/usb/dvb-usb/digitv.h 
b/drivers/media/usb/dvb-usb/digitv.h
index 908c09f4966b..cf104689bdff 100644
--- a/drivers/media/usb/dvb-usb/digitv.h
+++ b/drivers/media/usb/dvb-usb/digitv.h
@@ -6,6 +6,9 @@
 
 struct digitv_state {
 int is_nxt6000;
+
+unsigned char sndbuf[7];
+unsigned char rcvbuf[7];
 };
 
 /* protocol (from usblogging and the SDK:
-- 
2.7.4


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