Re: dvbv5-tzap with pctv 290e/292e needs EAGAIN for pat/pmt to work when recording.

[Andy Furniss <adf.lists@gmail.com>]

Mauro Carvalho Chehab wrote:
> Em Wed, 10 Jun 2015 18:27:30 +0100
> Andy Furniss <adf.lists@gmail.com> escreveu:
>
>> Mauro Carvalho Chehab wrote:
>>
>>> Just applied a fix for it:
>>> 	http://git.linuxtv.org/cgit.cgi/v4l-utils.git/commit/?id=c7c9af17163f282a147ea76f1a3c0e9a0a86e7fa
>>>
>>> It will retry up to 10 times. This should very likely be enough if the
>>> driver doesn't have any bug.
>>>
>>> Please let me know if this fixes the issue.
>>
>> No, it doesn't, so I reverted the above and added back my hack + a
>> counter as below and it seems to be retrying > a million times.
>
> Hmm.... that's likely a bug at the demod driver. It doesn't make much
> sense to keep a mutex hold for that long.
>
> Anyway, I modified the patch to use a timeout of 1 second, instead of
> trying 10 times. It is still a hack, as IMHO this is a driver bug,
> but it should produce a better result.
>
> Please check if the patch below works for you.
>
> You may change the MAX_TIME there if 1 second is not enough.
>
> It could be interesting if you add a printf with the difference
> between start and end time, for us to have an idea about how
> much time the driver is kept on such unreliable state.
>
> Thanks!
> Mauro
>
>
> [PATCH] libdvbv5: use a timeout for ioctl
>
> Some frontends don't play nice: they return -EAGAIN if the
> device doesn't lock. That actually means that it may take
> some time for some ioctl's to succeed. On experimental tests,
> the loop may happen ~2 million times!
>
> Well, better to waste power on a loop than to fail. So, let's
> change the code that detects EAGAIN by a loop that waits up
> to 1 second.
>
> This is not the right thing to do, but the Kernel drivers
> require fixes. We can do it only for newer versions of the
> Kernel.

I can't get this to work - it instantly bails -

read_sections: read error: Resource temporarily unavailable
couldn't find pmt-pid for sid 10bf

will try more later/tomorrow.

I notice there are a couple of suspect bitwise | but changing to || 
didn't help.

>
> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
>
> diff --git a/lib/libdvbv5/dvb-demux.c b/lib/libdvbv5/dvb-demux.c
> index 867d7b9dddde..af124ae3a7cc 100644
> --- a/lib/libdvbv5/dvb-demux.c
> +++ b/lib/libdvbv5/dvb-demux.c
> @@ -30,6 +30,7 @@
>   #include <string.h>
>   #include <unistd.h>
>   #include <stdio.h>
> +#include <time.h>
>   #include <errno.h>
>
>   #include <sys/ioctl.h>
> @@ -40,12 +41,25 @@
>
>   #include <libdvbv5/dvb-demux.h>
>
> +#define MAX_TIME		10	/* 1.0 seconds */
> +
>   #define xioctl(fh, request, arg...) ({					\
> -	int __rc, __retry;						\
> +	int __rc;							\
> +	struct timespec __start, __end;					\
>   									\
> -	for (__retry = 0; __retry < 10; __retry++) {			\
> +	clock_gettime(CLOCK_MONOTONIC, &__start);			\
> +	do {								\
>   		__rc = ioctl(fh, request, ##arg);			\
> -	} while (__rc == -1 && ((errno == EINTR) || (errno == EAGAIN)));\
> +		if (__rc != -1)						\
> +			break;						\
> +		if (!((errno == EINTR) | (errno == EAGAIN)))		\
> +			break;						\
> +		clock_gettime(CLOCK_MONOTONIC, &__end);			\
> +		if (__end.tv_sec * 10 + __end.tv_nsec / 100000000 >	\
> +		    __start.tv_sec * 10 + __start.tv_nsec / 100000000 +	\
> +		    MAX_TIME)						\
> +			break;						\
> +	} while (1);							\
>   									\
>   	__rc;								\
>   })
> diff --git a/lib/libdvbv5/dvb-fe.c b/lib/libdvbv5/dvb-fe.c
> index 48b09cd9ceaa..8607401841f2 100644
> --- a/lib/libdvbv5/dvb-fe.c
> +++ b/lib/libdvbv5/dvb-fe.c
> @@ -26,6 +26,7 @@
>   #include <inttypes.h>
>   #include <math.h>
>   #include <stddef.h>
> +#include <time.h>
>   #include <unistd.h>
>
>   #include <config.h>
> @@ -43,12 +44,25 @@ static int libdvbv5_initialized = 0;
>
>   # define N_(string) string
>
> +#define MAX_TIME		10	/* 1.0 seconds */
> +
>   #define xioctl(fh, request, arg...) ({					\
> -	int __rc, __retry;						\
> +	int __rc;							\
> +	struct timespec __start, __end;					\
>   									\
> -	for (__retry = 0; __retry < 10; __retry++) {			\
> +	clock_gettime(CLOCK_MONOTONIC, &__start);			\
> +	do {								\
>   		__rc = ioctl(fh, request, ##arg);			\
> -	} while (__rc == -1 && ((errno == EINTR) || (errno == EAGAIN)));\
> +		if (__rc != -1)						\
> +			break;						\
> +		if (!((errno == EINTR) | (errno == EAGAIN)))		\
> +			break;						\
> +		clock_gettime(CLOCK_MONOTONIC, &__end);			\
> +		if (__end.tv_sec * 10 + __end.tv_nsec / 100000000 >	\
> +		    __start.tv_sec * 10 + __start.tv_nsec / 100000000 +	\
> +		    MAX_TIME)						\
> +			break;						\
> +	} while (1);							\
>   									\
>   	__rc;								\
>   })
>
>