From: Peter Rosin <peda@axentia.se>
To: Wolfram Sang <wsa@the-dreams.de>
Cc: linux-kernel@vger.kernel.org,
Vadim Pasternak <vadimp@mellanox.com>,
Michael Shych <michaelsh@mellanox.com>,
Guenter Roeck <linux@roeck-us.net>,
Akinobu Mita <akinobu.mita@gmail.com>,
Jean Delvare <jdelvare@suse.com>,
linux-i2c@vger.kernel.org
Subject: Re: [PATCH 1/5] i2c: smbus: add unlocked __i2c_smbus_xfer variant
Date: Tue, 26 Jun 2018 13:54:01 +0200 [thread overview]
Message-ID: <79E4A06C-26EF-4FF4-AFEA-7E7769FDF995@axentia.se> (raw)
In-Reply-To: <20180626023757.l54suaryim2fieq3@ninjato>
On June 26, 2018 4:37:58 AM GMT+02:00, Wolfram Sang <wsa@the-dreams.de> wrote:
>
>> This is not perfectly equivalent, since i2c_smbus_xfer was callable
>from
>> atomic/irq context if you happened to end up emulating SMBus with an
>I2C
>> transfer, and that is no longer the case with this patch. It is
>unknown
>> (to me) if anything depends on that quirk, but it seems fragile
>enough to
>> simply break those cases and require them to call i2c_transfer
>directly
>> instead.
>
>Couldn't we just add the same trylock-code path here as well? I always
>wondered why I2C and SMBus were not in sync when it came to that. Yet,
>I
>didn't want to change the code for no reason, but it seems we now have
>one?
>
>Rest of the series looks good to me, very nice diffstat!
I don't think it's that easy as I just thought about another problem with lifting the locking from the emulation function. It calls kzalloc(..., GFP_KERNEL), at least in some cases, and that's not a very good idea from atomic/irq context...
Cheers,
Peter
next prev parent reply other threads:[~2018-06-26 11:54 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-20 8:51 [PATCH 0/5] i2c: smbus: add unlocked __i2c_smbus_xfer variant Peter Rosin
2018-06-20 8:51 ` [PATCH 1/5] " Peter Rosin
2018-06-26 2:37 ` Wolfram Sang
2018-06-26 11:54 ` Peter Rosin [this message]
2018-06-26 13:46 ` Wolfram Sang
2018-06-27 4:18 ` Peter Rosin
2018-06-27 7:08 ` Wolfram Sang
2018-07-01 12:13 ` Wolfram Sang
2018-07-01 16:40 ` Peter Rosin
2018-06-20 8:51 ` [PATCH 2/5] i2c: mux: mlxcpld: make use of __i2c_smbus_xfer Peter Rosin
2018-06-20 9:11 ` Michael Shych
2018-06-20 8:51 ` [PATCH 3/5] i2c: mux: pca9541: " Peter Rosin
2018-06-20 8:51 ` [PATCH 4/5] i2c: mux: pca954x: " Peter Rosin
2018-06-20 8:51 ` [PATCH 5/5] i2c: mux: " Peter Rosin
2018-07-03 21:01 ` [PATCH 0/5] i2c: smbus: add unlocked __i2c_smbus_xfer variant Wolfram Sang
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