[linux-dvb] Support of Nova S SE DVB card missing

Oliver Endriss o.endriss at gmx.de
Sun Aug 24 06:56:43 CEST 2008


Oliver Endriss wrote:
> Patrick Boettcher wrote:
> > On Sat, 23 Aug 2008, Oliver Endriss wrote:
> > >> In addition (see my other mail in that thread), sending two independent
> > >> i2c_transfers which actually belong together is not really safe.
> > >
> > > The current code in the else path will *never* work, because the tuner
> > > does not support repeated start conditions. The problem is not the I2C
> > > master (saa7146/flexcop) but the I2C slave (s5h1420).
> > 
> > Wouldn't it be more correct to have a flag signaling to the 
> > i2c_tranfer-function that a repeated start is not wanted even though it is 
> > two i2c-messages glued (which are interpreted today as a read with
> > repeated start).
> I remember that we had the same discussion for the stv0297 driver a long
> time ago.

for this interesting discussion.

Obviously the i2c maintainers were not willing to add the I2C_M_STOP

> For the stv0297 I have an experimental patch which intercepts the
> master_xfer routine, but this is not very nice either.

See attachment. It will probably not apply to the current tree, but you
should get the idea. Anyway, I don't want to add this crap to a frontend
driver. It does not fix the userspace issues anyway.

For now I suggest to use the good old double i2c_transfer() approach for
the budget driver.

Btw, I still do not understand how your repeated_start_workaround works.
  struct i2c_msg msg[] = {
    { .addr = state->config->demod_address, .flags = 0, .buf = b, .len = 2 },
    { .addr = state->config->demod_address, .flags = 0, .buf = &reg, .len = 1 },
    { .addr = state->config->demod_address, .flags = I2C_M_RD, .buf = b, .len = 1 },
What does the flexcop master_xfer send over the i2c bus when it receives
these messages?


VDR Remote Plugin 0.4.0: http://www.escape-edv.de/endriss/vdr/
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