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From: Takashi Iwai <tiwai@suse.de>
To: Vitaly Rodionov <vitalyr@opensource.cirrus.com>
Cc: Jaroslav Kysela <perex@perex.cz>, Takashi Iwai <tiwai@suse.com>,
	<alsa-devel@alsa-project.org>, <patches@opensource.cirrus.com>,
	<linux-kernel@vger.kernel.org>,
	Lucas Tanure <tanureal@opensource.cirrus.com>,
	Stefan Binding <sbinding@opensource.cirrus.com>
Subject: Re: [PATCH v3 13/27] ALSA: hda/cs8409: Dont disable I2C clock between consecutive accesses
Date: Sun, 01 Aug 2021 10:03:55 +0200	[thread overview]
Message-ID: <s5h7dh51thw.wl-tiwai@suse.de> (raw)
In-Reply-To: <20210730151844.7873-14-vitalyr@opensource.cirrus.com>

On Fri, 30 Jul 2021 17:18:30 +0200,
Vitaly Rodionov wrote:
> 
> From: Lucas Tanure <tanureal@opensource.cirrus.com>
> 
> Only disable I2C clock 25 ms after not being used.
> 
> The current implementation enables and disables the I2C clock for each
> I2C transaction. Each enable/disable call requires two verb transactions.
> This means each I2C transaction requires a total of four verb transactions
> to enable and disable the clock.
> However, if there are multiple consecutive I2C transactions, it is not
> necessary to enable and disable the clock each time, instead it is more
> efficient to enable the clock for the first transaction, and disable it
> after the final transaction, which would improve performance.
> This is achieved by using a timeout which disables the clock if no request
> to enable the clock has occurred for 25 ms.
> 
> Signed-off-by: Lucas Tanure <tanureal@opensource.cirrus.com>
> Signed-off-by: Vitaly Rodionov <vitalyr@opensource.cirrus.com>
> Signed-off-by: Stefan Binding <sbinding@opensource.cirrus.com>
> ---
> 
> Changes in v2:
> - Improved delayed work start/cancel implementation, and re-worked commit message
>  adding more explanation why this was required. 
> 
> Changes in v3:
> - Cancel the disable timer, but do not wait for any running disable functions to finish.
>  If the disable timer runs out before cancel, the delayed work thread will be blocked,
>  waiting for the mutex to become unlocked. This mutex will be locked for the duration of
>  any i2c transaction, so the disable function will run to completion immediately
>  afterwards in the scenario. The next enable call will re-enable the clock, regardless.

This looks almost fine, but just a couple of thoughts:

- cancel_delayed_work_sync() means to it might keep the i2c enabled
  after that point (just cancel the pending work).
  Would it cause a inconsistency afterwards?

- A similar procedure is needed for suspend callback to cancel / flush
  the work.
  The shutdown is another question, but usually it's fine to without
  any special handling as long as the resource is kept.


thanks,

Takashi

  reply	other threads:[~2021-08-01  8:03 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-30 15:18 [PATCH v3 00/27] ALSA: hda/cirrus: Split generic cirrus HDA codecs and CS8490 bridge into separate modules Vitaly Rodionov
2021-07-30 15:18 ` [PATCH v3 01/27] ALSA: hda/cirrus: Move CS8409 HDA bridge to separate module Vitaly Rodionov
2021-07-30 15:18 ` [PATCH v3 02/27] ALSA: hda/cs8409: Move arrays of configuration to a new file Vitaly Rodionov
2021-07-30 15:18 ` [PATCH v3 03/27] ALSA: hda/cs8409: Use enums for register names and coefficients Vitaly Rodionov
2021-07-30 15:18 ` [PATCH v3 04/27] ALSA: hda/cs8409: Mask all CS42L42 interrupts on initialization Vitaly Rodionov
2021-07-30 15:18 ` [PATCH v3 05/27] ALSA: hda/cs8409: Reduce HS pops/clicks for Cyborg Vitaly Rodionov
2021-07-30 15:18 ` [PATCH v3 06/27] ALSA: hda/cs8409: Disable unnecessary Ring Sense for Cyborg/Warlock/Bullseye Vitaly Rodionov
2021-07-30 15:18 ` [PATCH v3 07/27] ALSA: hda/cs8409: Disable unsolicited responses during suspend Vitaly Rodionov
2021-07-30 15:18 ` [PATCH v3 08/27] ALSA: hda/cs8409: Disable unsolicited response for the first boot Vitaly Rodionov
2021-07-30 15:18 ` [PATCH v3 09/27] ALSA: hda/cs8409: Mask CS42L42 wake events Vitaly Rodionov
2021-07-30 15:18 ` [PATCH v3 10/27] ALSA: hda/cs8409: Simplify CS42L42 jack detect Vitaly Rodionov
2021-07-30 15:18 ` [PATCH v3 11/27] ALSA: hda/cs8409: Prevent I2C access during suspend time Vitaly Rodionov
2021-07-30 15:18 ` [PATCH v3 12/27] ALSA: hda/cs8409: Generalize volume controls Vitaly Rodionov
2021-07-30 15:18 ` [PATCH v3 13/27] ALSA: hda/cs8409: Dont disable I2C clock between consecutive accesses Vitaly Rodionov
2021-08-01  8:03   ` Takashi Iwai [this message]
2021-08-11 18:33     ` Vitaly Rodionov
2021-07-30 15:18 ` [PATCH v3 14/27] ALSA: hda/cs8409: Avoid setting the same I2C address for every access Vitaly Rodionov
2021-07-30 15:18 ` [PATCH v3 15/27] ALSA: hda/cs8409: Avoid re-setting the same page as the last access Vitaly Rodionov
2021-07-30 15:18 ` [PATCH v3 16/27] ALSA: hda/cs8409: Support i2c bulk read/write functions Vitaly Rodionov
2021-07-30 15:18 ` [PATCH v3 17/27] ALSA: hda/cs8409: Separate CS8409, CS42L42 and project functions Vitaly Rodionov
2021-07-30 15:18 ` [PATCH v3 18/27] ALSA: hda/cs8409: Move codec properties to its own struct Vitaly Rodionov
2021-07-30 15:18 ` [PATCH v3 19/27] ALSA: hda/cs8409: Support multiple sub_codecs for Suspend/Resume/Unsol events Vitaly Rodionov
2021-07-30 15:18 ` [PATCH v3 20/27] ALSA: hda/cs8409: Add Support to disable jack type detection for CS42L42 Vitaly Rodionov
2021-07-30 15:18 ` [PATCH v3 21/27] ALSA: hda/cs8409: Add support for dolphin Vitaly Rodionov
2021-07-30 15:18 ` [PATCH v3 22/27] ALSA: hda/cs8409: Enable Full Scale Volume for Line Out Codec on Dolphin Vitaly Rodionov
2021-07-30 15:18 ` [PATCH v3 23/27] ALSA: hda/cs8409: Set fixed sample rate of 48kHz for CS42L42 Vitaly Rodionov
2021-07-30 15:18 ` [PATCH v3 24/27] ALSA: hda/cs8409: Use timeout rather than retries for I2C transaction waits Vitaly Rodionov
2021-07-30 15:18 ` [PATCH v3 25/27] ALSA: hda/cs8409: Remove unnecessary delays Vitaly Rodionov
2021-07-30 15:18 ` [PATCH v3 26/27] ALSA: hda/cs8409: Follow correct CS42L42 power down sequence for suspend Vitaly Rodionov
2021-07-30 15:18 ` [PATCH v3 27/27] ALSA: hda/cs8409: Unmute/Mute codec when stream starts/stops Vitaly Rodionov

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