Re: [PATCH] eeprom: at24: Add support for large EEPROMs connected to SMBus adapters

From: Guenter Roeck <linux@roeck-us.net>
To: Wolfram Sang <wsa@the-dreams.de>
Cc: linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] eeprom: at24: Add support for large EEPROMs connected to SMBus adapters
Date: Fri, 27 Mar 2015 05:51:11 -0700	[thread overview]
Message-ID: <5515523F.9010609@roeck-us.net> (raw)
In-Reply-To: <20150327080947.GA900@katana>

On 03/27/2015 01:09 AM, Wolfram Sang wrote:
>
>> just to give you an update: I do have some code, but it is a bit messy,
>> and it doesn't work well for ds2482 (the chip behind it still hangs up
>> if I access it in parallel through i2c-dev). On top of that, it causes
>> pretty significant slow-downs when accessing other devices on the same
>> bus at the same time. Not surprising, I guess, since it expands the scope
>> of the bus lock significantly.
>
> Just to get a better idea: Did you try taking the adapter_lock before
> the two SMBus command which needed to be concatenated (and use
> smbus_xfer directly)?
>
I did. I didn't use smbus_xfer directly, though, but introduced lockless
versions of the various smbus commands, and kept using those.

Guenter