From: Andreas Dannenberg <dannenberg@ti.com> To: Mark Brown <broonie@kernel.org> Cc: <alsa-devel@alsa-project.org>, <devicetree@vger.kernel.org>, Liam Girdwood <lgirdwood@gmail.com>, Jaroslav Kysela <perex@perex.cz>, Takashi Iwai <tiwai@suse.com>, Rob Herring <robh+dt@kernel.org>, Pawel Moll <pawel.moll@arm.com>, Mark Rutland <mark.rutland@arm.com>, Ian Campbell <ijc+devicetree@hellion.org.uk>, Kumar Gala <galak@codeaurora.org>, <linux-kernel@vger.kernel.org> Subject: Re: [PATCH v3 2/2] ASoC: codecs: add support for TAS5720 digital amplifier Date: Fri, 13 May 2016 09:04:20 -0500 [thread overview] Message-ID: <20160513140420.GH9174@borg.dal.design.ti.com> (raw) In-Reply-To: <20160513115540.GI22038@sirena.org.uk> Mark, please see below... On Fri, May 13, 2016 at 12:55:40PM +0100, Mark Brown wrote: > On Tue, Apr 26, 2016 at 01:01:05PM -0500, Andreas Dannenberg wrote: > > On Tue, Apr 26, 2016 at 06:29:36PM +0100, Mark Brown wrote: > > > > Is the device actually going to mess up if someone sends it something > > > else or is it just going to ignore the extra bits (given that it's doing > > > autodetection anyway). > > > well in any of the left-justified modes (which are the only ones the > > driver supports) the device takes and processes as many bits as it can > > given the clock and divider settings. Any extra bits provided will get > > ignored, and the next sync happens on the frame sync signal and not by > > counting bits so there is no downside also as confirmed by some bench > > testing I did feeding in 32-bit long frames for one channel. This seems > > like a case of preferring tolerance over strictly enforcing > > datasheet-advertised bit-widths. Will take out the check code. > > OK, accepting extra bits is fine. You should set sig_bits in the DAI so > userspace can see what's going on if it cares. I just had a quick look to see what sig_bits does, yes this is a good addition. Will post a follow-up patch based on the driver that you already accepted into your tree. (Btw I'm working on another codec driver and I don't stop getting positively surprised how flexible and powerful the overall ASoC framework is). Regards, Andreas > > Along these lines, earlier as I was rummaging through the existing > > drivers looking for a solution I could model after I noticed that > > most(?) ASoC codec drivers don't have any type of HW fault checking, at > > at least whatever drivers I looked at. Not sure why this is but given > > this discussion this seems like a general opportunity to make > > improvements. > > There are some with over temperature handling (eg, wm8962) but it's > relatively uncommon for observable protection features to be implemented > in silicon and even rarer for the interrupts to be hooked up (and hence > useful to support in software) unless there is also accessory detection > in the device. On older devices the required digital logic was often > excessively expensive and realistically only relatively high power > speaker drivers have much risk of something going wrong - things like > headphone outputs or smaller speaker drivers end up with protection from > their supplies collapsing well before the device is in physical danger.
WARNING: multiple messages have this Message-ID (diff)
From: Andreas Dannenberg <dannenberg@ti.com> To: Mark Brown <broonie@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com>, devicetree@vger.kernel.org, alsa-devel@alsa-project.org, Pawel Moll <pawel.moll@arm.com>, Ian Campbell <ijc+devicetree@hellion.org.uk>, linux-kernel@vger.kernel.org, Takashi Iwai <tiwai@suse.com>, Liam Girdwood <lgirdwood@gmail.com>, Rob Herring <robh+dt@kernel.org>, Kumar Gala <galak@codeaurora.org> Subject: Re: [PATCH v3 2/2] ASoC: codecs: add support for TAS5720 digital amplifier Date: Fri, 13 May 2016 09:04:20 -0500 [thread overview] Message-ID: <20160513140420.GH9174@borg.dal.design.ti.com> (raw) In-Reply-To: <20160513115540.GI22038@sirena.org.uk> Mark, please see below... On Fri, May 13, 2016 at 12:55:40PM +0100, Mark Brown wrote: > On Tue, Apr 26, 2016 at 01:01:05PM -0500, Andreas Dannenberg wrote: > > On Tue, Apr 26, 2016 at 06:29:36PM +0100, Mark Brown wrote: > > > > Is the device actually going to mess up if someone sends it something > > > else or is it just going to ignore the extra bits (given that it's doing > > > autodetection anyway). > > > well in any of the left-justified modes (which are the only ones the > > driver supports) the device takes and processes as many bits as it can > > given the clock and divider settings. Any extra bits provided will get > > ignored, and the next sync happens on the frame sync signal and not by > > counting bits so there is no downside also as confirmed by some bench > > testing I did feeding in 32-bit long frames for one channel. This seems > > like a case of preferring tolerance over strictly enforcing > > datasheet-advertised bit-widths. Will take out the check code. > > OK, accepting extra bits is fine. You should set sig_bits in the DAI so > userspace can see what's going on if it cares. I just had a quick look to see what sig_bits does, yes this is a good addition. Will post a follow-up patch based on the driver that you already accepted into your tree. (Btw I'm working on another codec driver and I don't stop getting positively surprised how flexible and powerful the overall ASoC framework is). Regards, Andreas > > Along these lines, earlier as I was rummaging through the existing > > drivers looking for a solution I could model after I noticed that > > most(?) ASoC codec drivers don't have any type of HW fault checking, at > > at least whatever drivers I looked at. Not sure why this is but given > > this discussion this seems like a general opportunity to make > > improvements. > > There are some with over temperature handling (eg, wm8962) but it's > relatively uncommon for observable protection features to be implemented > in silicon and even rarer for the interrupts to be hooked up (and hence > useful to support in software) unless there is also accessory detection > in the device. On older devices the required digital logic was often > excessively expensive and realistically only relatively high power > speaker drivers have much risk of something going wrong - things like > headphone outputs or smaller speaker drivers end up with protection from > their supplies collapsing well before the device is in physical danger.
next prev parent reply other threads:[~2016-05-13 14:10 UTC|newest] Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-04-25 20:17 [PATCH v3 0/2] ASoC: codecs: add support for TAS5720 digital amplifier Andreas Dannenberg 2016-04-25 20:17 ` Andreas Dannenberg 2016-04-25 20:17 ` [PATCH v3 1/2] ASoC: codecs: add TA5720 digital amplifier DT bindings Andreas Dannenberg 2016-04-25 20:17 ` Andreas Dannenberg 2016-04-26 15:37 ` Mark Brown 2016-04-26 15:37 ` Mark Brown 2016-04-26 16:14 ` Andreas Dannenberg 2016-04-26 16:14 ` Andreas Dannenberg 2016-04-26 16:50 ` Mark Brown 2016-04-26 16:50 ` Mark Brown 2016-04-26 17:00 ` Andreas Dannenberg 2016-04-26 17:00 ` Andreas Dannenberg 2016-04-25 20:17 ` [PATCH v3 2/2] ASoC: codecs: add support for TAS5720 digital amplifier Andreas Dannenberg 2016-04-25 20:17 ` Andreas Dannenberg 2016-04-26 15:43 ` Mark Brown 2016-04-26 15:43 ` Mark Brown 2016-04-26 16:22 ` Andreas Dannenberg 2016-04-26 16:22 ` Andreas Dannenberg 2016-04-26 17:29 ` Mark Brown 2016-04-26 17:29 ` Mark Brown 2016-04-26 18:01 ` Andreas Dannenberg 2016-04-26 18:01 ` Andreas Dannenberg 2016-05-13 11:55 ` Mark Brown 2016-05-13 14:04 ` Andreas Dannenberg [this message] 2016-05-13 14:04 ` Andreas Dannenberg 2016-04-26 17:19 ` Andrew F. Davis 2016-04-26 17:19 ` Andrew F. Davis 2016-04-26 17:37 ` Andreas Dannenberg 2016-04-26 17:37 ` Andreas Dannenberg
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