From: "Sverdlin, Alexander" <alexander.sverdlin@siemens.com>
To: "alexander.stein@ew.tq-group.com" <alexander.stein@ew.tq-group.com>
Cc: "kernel@pengutronix.de" <kernel@pengutronix.de>,
"linux-imx@nxp.com" <linux-imx@nxp.com>,
"s.hauer@pengutronix.de" <s.hauer@pengutronix.de>,
"festevam@gmail.com" <festevam@gmail.com>,
"shawnguo@kernel.org" <shawnguo@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-i2c@vger.kernel.org" <linux-i2c@vger.kernel.org>,
"aisheng.dong@nxp.com" <aisheng.dong@nxp.com>
Subject: Re: [PATCH] i2c: lpi2c: cache peripheral clock rate
Date: Thu, 9 Mar 2023 14:54:56 +0000 [thread overview]
Message-ID: <efeedfe844926b3a8484dc3f9913fa3792238b4c.camel@siemens.com> (raw)
In-Reply-To: <3718474.iIbC2pHGDl@steina-w>
Hi!
On Thu, 2023-03-09 at 15:37 +0100, Alexander Stein wrote:
> From: Alexander Sverdlin <alexander.sverdlin@siemens.com>
> >
> > One of the reasons to do it is to save some CPU cycles on
> > cpu_freq_get()
> > under mutex. The second reason if the (false-positive) lockdep
> > splat caused
> > by the recursive feature of the "prepare_lock" (one clock instance
> > is I2C
> > peripheral clock and another is pcf85063 RTC as clock provider):
> >
> > ======================================================
> > WARNING: possible circular locking dependency detected
> > 5.15.71+... #1 Tainted: G O
>
> Which kernel is this? Mainline or downstream vendor kernel?
found and tested on downstream vendor kernel.
[...]
>
>
> What if the peripheral clock rate changes? I guess a notifier similar
> to
> 90ad2cbe88c2 ("i2c: imx: use clk notifier for rate changes") should
> be added
> as well.
>
Good point! Thank you for the hint!
--
Alexander Sverdlin
Siemens AG
www.siemens.com
prev parent reply other threads:[~2023-03-09 14:59 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-09 13:43 [PATCH] i2c: lpi2c: cache peripheral clock rate A. Sverdlin
2023-03-09 13:43 ` [PATCH v2] tty: serial: fsl_lpuart: fix race on RX DMA shutdown A. Sverdlin
2023-03-09 14:37 ` [PATCH] i2c: lpi2c: cache peripheral clock rate Alexander Stein
2023-03-09 14:54 ` Sverdlin, Alexander [this message]
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