On Tue 22 May 2012 13:06:25 Andy Walls wrote:
> Hans Verkuil <hverkuil@xxxxxxxxx> wrote
>
> >I'm getting this warning in the daily build:
> >
> >v4l-dvb-git/drivers/media/dvb/frontends/cx24110.c: In function
> >‘cx24110_read_ucblocks’:
> >v4l-dvb-git/drivers/media/dvb/frontends/cx24110.c:520:40: warning:
> >value computed is not used [-Wunused-value]
> >
> >It comes from this code:
> >
> >static int cx24110_read_ucblocks(struct dvb_frontend* fe, u32*
> >ucblocks)
> >{
> > struct cx24110_state *state = fe->demodulator_priv;
> >
> > if(cx24110_readreg(state,0x10)&0x40) {
> > /* the RS error counter has finished one counting window */
> > cx24110_writereg(state,0x10,0x60); /* select the byer reg */
> > cx24110_readreg(state, 0x12) |
> > (cx24110_readreg(state, 0x13) << 8) |
> > (cx24110_readreg(state, 0x14) << 16);
> > cx24110_writereg(state,0x10,0x70); /* select the bler reg */
> > state->lastbler=cx24110_readreg(state,0x12)|
> > (cx24110_readreg(state,0x13)<<8)|
> > (cx24110_readreg(state,0x14)<<16);
> > cx24110_writereg(state,0x10,0x20); /* start new count window */
> > }
> > *ucblocks = state->lastbler;
> >
> > return 0;
> >}
> >
> >This is the offending code:
> >
> > cx24110_readreg(state, 0x12) |
> > (cx24110_readreg(state, 0x13) << 8) |
> > (cx24110_readreg(state, 0x14) << 16);
> >
> >Is there a reason these registers are read without storing their value?
> >Or is it a bug?
> >
> >Regards,
> >
> > Hans
> >--
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>
> I would guess the safest thing to do is still perform the registers reads.
>
> Will adding a "(void)" cast to the beginning of the statement work?
Sure, that will work. But I just wonder if anyone actually knows *why* this
is done in this way. It would be nice to have a comment here describing the
reason (if there is one, of course).
Regards,
Hans
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