From 548ad8ee68c034300b714b297fe18b16a8a4f797 Mon Sep 17 00:00:00 2001 From: Mauro Carvalho Chehab Date: Mon, 22 Mar 2021 16:33:57 +0100 Subject: media: dvb_frontend: warn if frontend driver has API issues the kAPI for a frontend can use 3 different tuning methods: 1. The hardware tracks internally frequency shifts via its own internal zigzag logic; 2. The hardware has a custom zigzag method, implemented via fe search() ops; 3. The hardware doesn't have any internal zigzag logic. So, the Kernel needs to implement it. Drivers that use the in-kernel software zigzag are required to provide some parameters for the zigzag code to work. Failing to do that will just make the Kernel to tune several times to the very same frequency, delaying the tuning time for no good reason. This is actually a kAPI violation (and an uAPI one, as the frequency shift is exported to the uAPI). Emit a warning on such case, as the driver needs to be fixed. Link: https://lore.kernel.org/linux-media/6d5941e3ba77439bbc401207cd87d9b8748d5cb8.1616427172.git.mchehab+huawei@kernel.org Signed-off-by: Mauro Carvalho Chehab --- drivers/media/dvb-core/dvb_frontend.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/media/dvb-core/dvb_frontend.c b/drivers/media/dvb-core/dvb_frontend.c index 6aaa4d5a504d..a6915582d1a6 100644 --- a/drivers/media/dvb-core/dvb_frontend.c +++ b/drivers/media/dvb-core/dvb_frontend.c @@ -481,6 +481,10 @@ static void dvb_frontend_swzigzag(struct dvb_frontend *fe) struct dvb_frontend_private *fepriv = fe->frontend_priv; struct dtv_frontend_properties *c = &fe->dtv_property_cache, tmp; + if (fepriv->max_drift) + dev_warn_once(fe->dvb->device, + "Frontend requested software zigzag, but didn't set the frequency step size\n"); + /* if we've got no parameters, just keep idling */ if (fepriv->state & FESTATE_IDLE) { fepriv->delay = 3 * HZ; -- cgit v1.2.3