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From: Mikko Perttunen <cyndis@kapsi.fi>
To: David Laight <David.Laight@ACULAB.COM>,
	'Mikko Perttunen' <mperttunen@nvidia.com>,
	"ldewangan@nvidia.com" <ldewangan@nvidia.com>,
	"digetx@gmail.com" <digetx@gmail.com>,
	"thierry.reding@gmail.com" <thierry.reding@gmail.com>,
	"jonathanh@nvidia.com" <jonathanh@nvidia.com>,
	"wsa@kernel.org" <wsa@kernel.org>
Cc: "linux-i2c@vger.kernel.org" <linux-i2c@vger.kernel.org>,
	"linux-tegra@vger.kernel.org" <linux-tegra@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"stable@vger.kernel.org" <stable@vger.kernel.org>
Subject: Re: [PATCH] i2c: tegra: Wait for config load atomically while in ISR
Date: Mon, 11 Jan 2021 16:38:06 +0200	[thread overview]
Message-ID: <9ba3d704-674b-94df-d10f-e3edb3c695d6@kapsi.fi> (raw)
In-Reply-To: <a0b0f224c2864b80a5bac53646d67daf@AcuMS.aculab.com>

Agreed that this is possibly not optimal, but this patch simply returns 
the behavior to what it was before "i2c: tegra: Support atomic 
transfers", fixing the overt issue.

Design fixes can be considered later, in a non-stable patch.

Mikko

On 1/11/21 4:31 PM, David Laight wrote:
> 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
> 
> -
> Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
> Registration No: 1397386 (Wales)
> 

  reply	other threads:[~2021-01-11 14:39 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-11 13:55 [PATCH] i2c: tegra: Wait for config load atomically while in ISR Mikko Perttunen
2021-01-11 14:31 ` David Laight
2021-01-11 14:38   ` Mikko Perttunen [this message]
2021-01-11 15:14 ` Dmitry Osipenko
2021-01-11 15:52   ` Mikko Perttunen

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