From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx1.redhat.com ([209.132.183.28]:14361 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753020Ab1KXQiV (ORCPT ); Thu, 24 Nov 2011 11:38:21 -0500 Message-ID: <4ECE72F5.4080107@redhat.com> Date: Thu, 24 Nov 2011 14:38:13 -0200 From: Mauro Carvalho Chehab MIME-Version: 1.0 To: Lawrence Rust CC: Andreas Oberritter , Linux Media Mailing List Subject: Re: [PATCH] Revert most of 15cc2bb [media] DVB: dtv_property_cache_submit shouldn't modifiy the cache References: <1320506379.1731.12.camel@gagarin> <4EB566CD.7050704@linuxtv.org> <1320513624.1731.20.camel@gagarin> <4EB574A3.8050503@linuxtv.org> <1320515855.1731.28.camel@gagarin> In-Reply-To: <1320515855.1731.28.camel@gagarin> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: Em 05-11-2011 15:57, Lawrence Rust escreveu: > On Sat, 2011-11-05 at 18:38 +0100, Andreas Oberritter wrote: > [snip] >> I don't get how this could be useful. MythTV knows what delivery system >> it wants to use, so it should pass this information to the kernel. >> Trying to set an invalid delivery system must fail. >> >> Using SYS_UNDEFINED as a pre-set default is different from setting >> SYS_UNDEFINED from userspace, which should always generate an error IMO, >> unless this is documented otherwise in the API specification. > > It's not ideal that MythTV is setting DTV_DELIVERY_SYSTEM to 0 and I > have filed a bug against this. But that doesn't change the fact that > the original patch significantly changed user parameter handling for no > significant benefit. MythTV is probably the biggest client of v4l and > will greatly hinder users upgrading to (Myth)Ubuntu 12.04 or Fedora 16 > both of which use Linux 3.x. Regression is a bad thing. However, in this specific case, I agree with Andreas: an assumption that the Kernel will replace SYS_UNDEFINED by something else is a very bad thing. It also hides a bug, as there are no way for devices that support more than one delivery system to properly select the desired one. So, this patch won't fix it. So, I suspect that you'll need to open a BZ also at Ubuntu and Fedora, in order to backport the MythTV fix into them. Regards, Mauro