Re: [PATCH] V4L/DVB: budget-av: wait longer for frontend to power on

[Oliver Endriss <o.endriss@gmx.de>]

Mauro Carvalho Chehab wrote:
> Bjørn Mork wrote:
> > Some devices need much more time than 100ms to power on, leading to a
> > failure to enable the frontend on the first attempt. Instead we get
> > 
> > [   38.194200] saa7146: register extension 'budget_av'.
> > [   38.253828] budget_av 0000:05:01.0: PCI INT A -> GSI 17 (level, low) -> IRQ 17
> > [   38.601572] saa7146: found saa7146 @ mem ffffc90000c6ac00 (revision 1, irq 17) (0x1894,0x0022).
> > [   39.251324] saa7146 (0): dma buffer size 1347584
> > [   39.306757] DVB: registering new adapter (KNC1 DVB-C MK3)
> > [   39.462785] adapter failed MAC signature check
> > [   39.516159] encoded MAC from EEPROM was ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff
> > [   39.892397] KNC1-0: MAC addr = 00:09:d6:6d:94:5c
> > [   40.552028] saa7146 (0) saa7146_i2c_writeout [irq]: timed out waiting for end of xfer
> > [   40.580044] saa7146 (0) saa7146_i2c_writeout [irq]: timed out waiting for end of xfer
> > [   40.608026] saa7146 (0) saa7146_i2c_writeout [irq]: timed out waiting for end of xfer
> > [   40.636027] saa7146 (0) saa7146_i2c_writeout [irq]: timed out waiting for end of xfer
> > [   40.652026] DVB: TDA10023(-1): tda10023_writereg, writereg error (reg == 0x00, val == 0x33, ret == -5)
> > [   40.664027] saa7146 (0) saa7146_i2c_writeout [irq]: timed out waiting for end of xfer
> > [   40.692027] saa7146 (0) saa7146_i2c_writeout [irq]: timed out waiting for end of xfer
> > [   40.720027] saa7146 (0) saa7146_i2c_writeout [irq]: timed out waiting for end of xfer
> > [   40.748027] saa7146 (0) saa7146_i2c_writeout [irq]: timed out waiting for end of xfer
> > [   40.764025] DVB: TDA10023(-1): tda10023_readreg: readreg error (reg == 0x1a, ret == -5)
> > [   40.764067] budget-av: A frontend driver was not found for device [1131:7146] subsystem [1894:0022]
> > 
> > Unloading and the reloading the driver will work around this problem.  But
> > it can also be easily fixed by increasing the wait period after powering
> > on.  The optimum value is unclear to me.  But I've found the 500 ms is not
> > enough.  5 s is enough for my card, but might be more than actually needed.
> > However, as long as we don't handle this failure more gracefully, then the
> > timeout need to be long enough.
> > 
> > Signed-off-by: Bjørn Mork <bjorn@mork.no>
> > Cc: stable@kernel.org
> > ---
> > Hello,
> > 
> > I have recently bought a KNC1 clone, called Mystique CaBiX-C2.  This card 
> > would just not work on reboot in my system, giving the errors shown above.
> > Unloading the module and then loading it again always fixed the problem,
> > indicating that it was just a startup timing problem.
> > 
> > As you can see, the i2c timeouts are from the frontend attach function, 
> > tda10023_attach():
> > 	/* wakeup if in standby */
> > 	tda10023_writereg (state, 0x00, 0x33);
> > 	/* check if the demod is there */
> > 	if ((tda10023_readreg(state, 0x1a) & 0xf0) != 0x70) goto error;
> > 
> > cleary showing that it just isn't responding yet at that point.
> > 
> > I first tried increasing the msleep() to 500 ms, but still got the same
> > error.  Increasing it to 5000 ms helped, however, and made my card work
> > from boot.  I have not tried any values inbetween, as each attempt AFAIK
> > requires a reboot to get the card into the "cold state" where it will
> > fail.
> > 
> > dmesg with the patch installed:
> > 
> > [   37.786955] saa7146: register extension 'budget_av'.
> > [   37.846592] budget_av 0000:05:01.0: PCI INT A -> GSI 17 (level, low) -> IRQ 17
> > [   37.933318] saa7146: found saa7146 @ mem ffffc90000c70c00 (revision 1, irq 17) (0x1894,0x0022).
> > [   38.037851] saa7146 (0): dma buffer size 1347584
> > [   38.093224] DVB: registering new adapter (KNC1 DVB-C MK3)
> > [   38.194254] adapter failed MAC signature check
> > [   38.247527] encoded MAC from EEPROM was ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff
> > [   38.622678] KNC1-0: MAC addr = 00:09:d6:6d:94:5c
> > [   43.765897] DVB: registering adapter 0 frontend 0 (Philips TDA10023 DVB-C)...
> > [   43.851587] budget-av: ci interface initialised.
> > 
> > Please consider this patch.  Or maybe it is possible to wait smarter,
> > testing actual frontend power status instead of just a blind sleep?
> > 
> > I've also included a CC stable as I've had the same problem with the 2.6.32
> > and 2.6.33 stable drivers.
> 
> Are you sure you really need 5 seconds to initialize? This time is probably
> board-specific, and shouldn't be applied as-is. So, if you really need such
> high timeout, it should be added inside the switch.
> 
> I dunno if is there a way to test if the power-on cycle has completed,
> but for sure an approach like that would be better than blindly waiting
> for 5 secs.

Mauro, please do not apply this patch!

Afaik there is no tuner which takes 5 seconds to initialize. (And if
there was one, it would be a bad idea to add a 5s delay for all tuners!)

The saa7146_i2c_writeout errors are likely caused by broken hardware.

CU
Oliver

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