From mboxrd@z Thu Jan 1 00:00:00 1970 From: Takashi Iwai Subject: Re: [PATCH RFC 5/9] ALSA: core: selection of audio_tstamp type and accuracy reports Date: Wed, 10 Dec 2014 17:35:55 +0100 Message-ID: References: <1418077426-8309-1-git-send-email-pierre-louis.bossart@linux.intel.com> <1418077426-8309-6-git-send-email-pierre-louis.bossart@linux.intel.com> Mime-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mx2.suse.de (cantor2.suse.de [195.135.220.15]) by alsa0.perex.cz (Postfix) with ESMTP id 7F387260564 for ; Wed, 10 Dec 2014 17:35:55 +0100 (CET) In-Reply-To: <1418077426-8309-6-git-send-email-pierre-louis.bossart@linux.intel.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: alsa-devel-bounces@alsa-project.org To: Pierre-Louis Bossart Cc: alsa-devel@alsa-project.org List-Id: alsa-devel@alsa-project.org Just a minor issue before going to detailed review: At Mon, 8 Dec 2014 16:23:42 -0600, Pierre-Louis Bossart wrote: > > +/* user space provides config to kernel */ > +struct snd_pcm_audio_tstamp_config { > + __u32 type_requested:4; > + __u32 report_delay:1; /* add total delay to A/D or D/A */ > +}; .... > +/* kernel provides report to user-space */ > +struct snd_pcm_audio_tstamp_report { > + /* actual type if hardware could not support requested timestamp */ > + __u32 actual_type:4; > + > + /* accuracy represented in mantissa/exponent form */ > + __u32 accuracy_report:1; /* 0 if accuracy unknown, 1 if rest of structure is valid */ > + __u32 accuracy_m:7; /* 0..127, ~3 significant digit for mantissa */ > + __u32 accuracy_e:4; /* base10 exponent, 0 for ns, 3 for us, 6 for ms, 9 for s */ > +}; Please avoid the bit fields in these, since these values will be a part of ABI. There is absolutely no compatibility when you're using bitfields. Use the explicit bit operations. thanks, Takashi