linux-kernel - RE: [PATCH] i2c: tegra: Wait for config load atomically while in ISR

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Message-ID: <a0b0f224c2864b80a5bac53646d67daf@AcuMS.aculab.com>
Date:   Mon, 11 Jan 2021 14:31:36 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Mikko Perttunen' <mperttunen@...dia.com>,
        "ldewangan@...dia.com" <ldewangan@...dia.com>,
        "digetx@...il.com" <digetx@...il.com>,
        "thierry.reding@...il.com" <thierry.reding@...il.com>,
        "jonathanh@...dia.com" <jonathanh@...dia.com>,
        "wsa@...nel.org" <wsa@...nel.org>
CC:     "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
        "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: RE: [PATCH] i2c: tegra: Wait for config load atomically while in ISR

From: Mikko Perttunen
> Sent: 11 January 2021 13:56
> 
> Upon a communication error, the interrupt handler can call
> tegra_i2c_disable_packet_mode. This causes a sleeping poll to happen
> unless the current transaction was marked atomic. Since
> tegra_i2c_disable_packet_mode is only called from the interrupt path,
> make it use atomic waiting always.

Spin-waiting in an ISR for anything that it makes sense to do
a sleep-wait for at other times is badly broken design.

	David

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