[OpenWrt-Devel] [PATCH] uqmi: add timeout parameter

[Piotr Dymacz]

Hi Zefir,

On 07.11.2019 12:54, Zefir Kurtisi wrote:
> Working with Quectel EM12 LTE-module, we observe
> regular stalls of the QMI interface which cause
> a request issued by uqmi to hang forever.
> 
> Most reproducibly this happens after the device
> has been power-cycled and left untouched for a
> while (~ 60s+). Most of the time the very first
> QMI request fails, since it is not responded by
> the module. This is the strace from such a run
> (from --get-pin-status):
> 
>   open("/dev/cdc-wdm0", O_RDWR|O_EXCL|O_NOCTTY|O_NONBLOCK|O_LARGEFILE) = 6
>   fcntl64(6, F_GETFL)                     = 0x10802 (flags O_RDWR|O_NONBLOCK|O_LARGEFILE)
>   fcntl64(6, F_SETFL, O_RDWR|O_NONBLOCK|O_LARGEFILE) = 0
>   epoll_ctl(3, EPOLL_CTL_ADD, 6, {EPOLLIN|EPOLLRDHUP|EPOLLET, {u32=268567076, u64=1153486808202346496}}) = 0
>   write(6, "\1\17\0\0\0\0\0\1\"\0\4\0\1\1\0\2", 16) = 16
>   clock_gettime(CLOCK_MONOTONIC, {tv_sec=95, tv_nsec=583444789}) = 0
>   clock_gettime(CLOCK_MONOTONIC, {tv_sec=95, tv_nsec=583770264}) = 0
>   epoll_pwait(3,
>   [ hang forever ]
> 
> After killing the blocked uqmi process, the next
> request works as expected.
> 
> We don't know whether this is a device FW issue
> (we use the latest EM12GPAR01A15M4G) or whether
> the device enters some undocumented power-save
> mode after idling for some time.

Could you share this firmware version, is that a generic Quectel or a 
customized one? I would like to reproduce and debug the problem but the 
EM12 I have here has 'EM12GPAR01A_11_M4G'.

Also, what platform do you use this modem with?

-- 
Cheers,
Piotr

> This patch extends uqmi with a timeout option
> (-t, --timeout <ms>) which if set terminates a
> request after the given amount of msecs. In
> our usecase it provides a means of preventing
> infinitively stuck QMI requests. Since we
> observe the issue only for the very first
> request after cold-boot, we use a dummy access
> early in qmi.sh, e.g.
>    uqmi -d /dev/cdc-wdm0 --get-pin-status -t 3000 >/dev/null 2>&1
> 
> This ensures the QMI interface is un-stuck in
> case it entered the stall-state observed. The
> change is intentionally not included in this
> commit, since you don't need it if it works
> for you.
> 
> 
> Signed-off-by: Zefir Kurtisi <zefir.kurtisi at neratec.com>
> ---
>   main.c | 15 ++++++++++++++-
>   1 file changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/main.c b/main.c
> index 9b43e5e..aa4634c 100644
> --- a/main.c
> +++ b/main.c
> @@ -44,6 +44,7 @@ static const struct option uqmi_getopt[] = {
>   	{ "keep-client-id", required_argument, NULL, 'k' },
>   	{ "release-client-id", required_argument, NULL, 'r' },
>   	{ "mbim",  no_argument, NULL, 'm' },
> +	{ "timeout", required_argument, NULL, 't' },
>   	{ NULL, 0, NULL, 0 }
>   };
>   #undef __uqmi_command
> @@ -57,6 +58,7 @@ static int usage(const char *progname)
>   		"  --keep-client-id <name>:          Keep Client ID for service <name>\n"
>   		"  --release-client-id <name>:       Release Client ID after exiting\n"
>   		"  --mbim, -m                        NAME is an MBIM device with EXT_QMUX support\n"
> +		"  --timeout, -t                     response timeout in msecs\n"
>   		"\n"
>   		"Services:                           dms, nas, pds, wds, wms\n"
>   		"\n"
> @@ -103,6 +105,14 @@ static void handle_exit_signal(int signal)
>   	uloop_end();
>   }
>   
> +static void _request_timeout_handler(struct uloop_timeout *timeout)
> +{
> +	fprintf(stderr, "Request timed out\n");
> +	handle_exit_signal(0);
> +}
> +
> +struct uloop_timeout request_timeout = { .cb = _request_timeout_handler, };
> +
>   int main(int argc, char **argv)
>   {
>   	static struct qmi_dev dev;
> @@ -112,7 +122,7 @@ int main(int argc, char **argv)
>   	signal(SIGINT, handle_exit_signal);
>   	signal(SIGTERM, handle_exit_signal);
>   
> -	while ((ch = getopt_long(argc, argv, "d:k:sm", uqmi_getopt, NULL)) != -1) {
> +	while ((ch = getopt_long(argc, argv, "d:k:smt:", uqmi_getopt, NULL)) != -1) {
>   		int cmd_opt = CMD_OPT(ch);
>   
>   		if (ch < 0 && cmd_opt >= 0 && cmd_opt < __UQMI_COMMAND_LAST) {
> @@ -136,6 +146,9 @@ int main(int argc, char **argv)
>   		case 'm':
>   			dev.is_mbim = true;
>   			break;
> +		case 't':
> +			uloop_timeout_set(&request_timeout, atol(optarg));
> +			break;
>   		default:
>   			return usage(argv[0]);
>   		}
> 


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