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From: Richard Fitzgerald <>
To: Mark Brown <>
Cc: <>, <>,
Subject: Re: [PATCH 04/12] ASoC: cs42l42: Don't reconfigure the PLL while it is running
Date: Tue, 10 Aug 2021 17:27:45 +0100	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On 10/08/2021 16:49, Mark Brown wrote:
> On Tue, Aug 10, 2021 at 04:37:51PM +0100, Richard Fitzgerald wrote:
>> cs42l42_pcm_hw_params() must only configure the PLL if this is the first
>> stream to become active, otherwise it will be overwriting the registers
>> while the PLL is running.
> Shouldn't the PLL code be noticing problematic attempts to reconfigure
> the PLL while it's active rather than the individual callers?

It's wrong for a hw_params() for one stream to try to configure the PLL
when the other stream has already called hw_params(), configured the PLL
and started it. E.g. if you started a PLAYBACK, configured and
started everything, then got another hw_params() for the CAPTURE.

cs42l42_pll_config() could check whether it is already running and skip
configuration in that case, but that seems to me a rather opaque
implementation. In my opinion this doesn't really fall into the case of
ignoring-bad-stuff-to-be-helpful (like free() accepting a NULL).

hw_params() deals with both playback and capture streams so it makes
sense to me that it should contain logic to ensure it isn't stomping on
the other stream it already set up, rather than have everything it calls
figure out whether it shouldn't have done that.

  reply	other threads:[~2021-08-10 16:27 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-10 15:37 [PATCH 00/12] ASoC: cs42l42: Series of bugfixes and improvements Richard Fitzgerald
2021-08-10 15:37 ` [PATCH 01/12] ASoC: cs42l42: Use PLL for SCLK > 12.188MHz Richard Fitzgerald
2021-08-10 15:37 ` [PATCH 02/12] ASoC: cs42l42: Don't claim to support 192k Richard Fitzgerald
2021-08-10 15:37 ` [PATCH 03/12] ASoC: cs42l42: Always configure both ASP TX channels Richard Fitzgerald
2021-08-10 15:37 ` [PATCH 04/12] ASoC: cs42l42: Don't reconfigure the PLL while it is running Richard Fitzgerald
2021-08-10 15:49   ` Mark Brown
2021-08-10 16:27     ` Richard Fitzgerald [this message]
2021-08-11 11:56       ` Mark Brown
2021-08-11 12:21         ` Richard Fitzgerald
2021-08-11 14:41           ` Mark Brown
2021-08-11 10:56     ` Richard Fitzgerald
2021-08-10 15:37 ` [PATCH 05/12] ASoC: cs42l42: Set correct SRC MCLK Richard Fitzgerald
2021-08-10 15:37 ` [PATCH 06/12] ASoC: cs42l42: Mark OSC_SWITCH_STATUS register volatile Richard Fitzgerald
2021-08-10 15:37 ` [PATCH 07/12] ASoC: cs42l42: Allow time for HP/ADC to power-up after enable Richard Fitzgerald
2021-08-10 15:37 ` [PATCH 08/12] ASoC: cs42l42: Prevent NULL pointer deref in interrupt handler Richard Fitzgerald
2021-08-10 15:37 ` [PATCH 09/12] ASoC: cs42l42: Remove runtime_suspend/runtime_resume callbacks Richard Fitzgerald
2021-08-10 15:37 ` [PATCH 10/12] ASoC: cs42l42: Remove redundant pll_divout member Richard Fitzgerald
2021-08-10 15:37 ` [PATCH 11/12] ASoC: cs42l42: Add HP Volume Scale control Richard Fitzgerald
2021-08-10 15:37 ` [PATCH 12/12] ASoC: cs42l42: Add control for audio slow-start switch Richard Fitzgerald

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