[linux-dvb] Re: PROC_FS patch and other stuff

[Holger Waechtler <holger@convergence.de>]

Hi,

I'd like to add this to the driver, but don't want to blow up the source 
for small STB's. Is it possible to encapsulate all this stuff into one 
or two extra files?

Holger


Dennis wrote:
> Hi,
> 
> I have made a patch to add procfs support to the DVB HEAD drivers, which gives 
> you something like:
> 
> /proc/dvb/
> /proc/dvb/adapter1
> /proc/dvb/adapter1/frontend0
> /proc/dvb/adapter1/frontend0/inversion
> /proc/dvb/adapter1/frontend0/symbol_rate
> /proc/dvb/adapter1/frontend0/modulation
> /proc/dvb/adapter1/frontend0/pwm
> /proc/dvb/adapter1/frontend0/ves1820
> /proc/dvb/adapter1/frontend0/ber
> /proc/dvb/adapter1/frontend0/uncorrected_blocks
> /proc/dvb/adapter1/frontend0/signal_strength
> /proc/dvb/adapter1/frontend0/SNR
> /proc/dvb/adapter1/frontend0/status
> /proc/dvb/adapter1/frontend0/caps
> /proc/dvb/adapter1/frontend0/type
> /proc/dvb/adapter1/frontend0/identify
> /proc/dvb/adapter1/frontend0/frequency
> /proc/dvb/adapter1/identify
> /proc/dvb/adapter0
> /proc/dvb/adapter0/frontend0
> /proc/dvb/adapter0/frontend0/inversion
> /proc/dvb/adapter0/frontend0/symbol_rate
> /proc/dvb/adapter0/frontend0/modulation
> /proc/dvb/adapter0/frontend0/pwm
> /proc/dvb/adapter0/frontend0/ves1820
> /proc/dvb/adapter0/frontend0/ber
> /proc/dvb/adapter0/frontend0/uncorrected_blocks
> /proc/dvb/adapter0/frontend0/signal_strength
> /proc/dvb/adapter0/frontend0/SNR
> /proc/dvb/adapter0/frontend0/status
> /proc/dvb/adapter0/frontend0/caps
> /proc/dvb/adapter0/frontend0/type
> /proc/dvb/adapter0/frontend0/identify
> /proc/dvb/adapter0/frontend0/frequency
> /proc/dvb/adapter0/identify
> 
> 
> Most items will look familiar, all of them output the current value, and the 
> relevant ones allow you to echo in a new value.
> 
> So you can tune a card by:
> echo "162000000" > /proc/dvb/adapter0/frontend0/frequency
> echo "QAM_64" > /proc/dvb/adapter0/frontend0/modulation
> echo "6900000" > /proc/dvb/adapter0/frontend0/symbol_rate
> 
> (NOTE: only DVB-C supported right now! But the DVB-C related proc entries are 
> only created if you have a DVB-C card, so if you try this with DVB-S or -T 
> you'll just get fewer proc entries).
> 
> and do:
> cat /proc/dvb/adapter0/frontend0/status
> FE_HAS_SIGNAL
> FE_HAS_CARRIER
> FE_HAS_VITERBI
> FE_HAS_SYNC
> FE_HAS_LOCK
> 
> Now, while a lot of fun can be had with this, my initial reason to write this 
> was to allow easy changing of the ves1820 register values, and the cards PWM 
> value, without recompiling the driver. This in order to find more optimal 
> values, and to be able to do it with a bash script :-)
> 
> Hence:
> vdr driver # cat /proc/dvb/adapter0/frontend0/ves1820
> VES1820 Register settings
> (QAM type, Register 1, Register 5, Register 8, Register 9)
>   QAM_16    140   164   162   145
>   QAM_32    140   120   116   150
>   QAM_64    106    70    67   106
>   QAM_128   106    54    52   126
>   QAM_256    92    38    35   107
> 
> And you can change these by for example:
> echo "QAM_16 111 222 333 444" > ./ves1820
> 
> Also the /proc/dvb/adapterX/frontend0/pwm value can be changed like this.
> 
> After a lot of playing with the register values, I got slight improvements in 
> BER value, but not much, and still a lot of block errors. For QAM_64, BER is 
> like 10,000, but for QAM_128, it is usually 600,000.
> 
> The PWM value however, I changed from 52 (other card default is 21?), to 40, 
> ("echo 40 > /proc/dvb/adapter0/frontend0/pwm") and now have a QAM_128 BER of 
> 10,000, and no block errors! Massive improvement, since before I used to 
> always have problems watching QAM_128 channels. The 40 value was a random 
> number I pulled out of an unnamed place :)
> 
> Anyways, this patch is probably nowhere near clean enough to add to the 
> drivers, but I think a lot of good things can be done with proc filesystem 
> support, and will happily take pointers from more knowledgable people on this 
> list in order to improve and add on this. 
> For example to add support of per-card register and PWM values I had to 
> shuffle a few things around. Some proc related functions should also be in 
> their own file.
> 
> So this is basically for the people who are interested in playing with the 
> ves1820 register and PWM values to find the optimal values. You can now do so 
> without recompiling, and the first one to write a nice Perl script (BASH is 
> OK too :-) to scan for the best values gets a free beer!
> 
> Cheers,
> Dennis
> 
> PS - There are a few additional printk's etc I have added over time to play 
> with, which are not really part of anything, and which I'll take out for the 
> "proper" patch.
> 
> PS2 - If you have PROC_FS enabled in your kernel, this patch will build with 
> PROC_FS automatically. If you disable this in dvb_procfs.h, you should get 
> the normal, clean HEAD driver.
> 
> 
> 
> -- This is where I put the patch last night, not as an attachment, but it 
> never went through anyway, probably too big? (35kb). Any suggestions where to 
> make it available? :-)
> 
> 
> 



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