linux-kernel - Re: [PATCH v7 16/24] i2c: allow adapter drivers to override the adapter locking

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Date:	Thu, 28 Apr 2016 23:08:26 +0200
From:	Peter Rosin <peda@...ntia.se>
To:	Wolfram Sang <wsa@...-dreams.de>
CC:	<linux-kernel@...r.kernel.org>, Jonathan Corbet <corbet@....net>,
	Peter Korsgaard <peter.korsgaard@...co.com>,
	Guenter Roeck <linux@...ck-us.net>,
	Jonathan Cameron <jic23@...nel.org>,
	Hartmut Knaack <knaack.h@....de>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Peter Meerwald <pmeerw@...erw.net>,
	Antti Palosaari <crope@....fi>,
	Mauro Carvalho Chehab <mchehab@....samsung.com>,
	Rob Herring <robh+dt@...nel.org>,
	Frank Rowand <frowand.list@...il.com>,
	Grant Likely <grant.likely@...aro.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"David S. Miller" <davem@...emloft.net>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Kalle Valo <kvalo@...eaurora.org>,
	Jiri Slaby <jslaby@...e.com>,
	Daniel Baluta <daniel.baluta@...el.com>,
	Lucas De Marchi <lucas.demarchi@...el.com>,
	Adriana Reus <adriana.reus@...el.com>,
	Matt Ranostay <matt.ranostay@...el.com>,
	Krzysztof Kozlowski <k.kozlowski@...sung.com>,
	Hans Verkuil <hans.verkuil@...co.com>,
	Terry Heo <terryheo@...gle.com>, Arnd Bergmann <arnd@...db.de>,
	Tommi Rantala <tt.rantala@...il.com>,
	Crestez Dan Leonard <leonard.crestez@...el.com>,
	<linux-i2c@...r.kernel.org>, <linux-doc@...r.kernel.org>,
	<linux-iio@...r.kernel.org>, <linux-media@...r.kernel.org>,
	<devicetree@...r.kernel.org>, Peter Rosin <peda@...ator.liu.se>
Subject: Re: [PATCH v7 16/24] i2c: allow adapter drivers to override the
 adapter locking



On 2016-04-28 22:50, Wolfram Sang wrote:
> On Wed, Apr 20, 2016 at 05:17:56PM +0200, Peter Rosin wrote:
>> Add i2c_lock_bus() and i2c_unlock_bus(), which call the new lock_bus and
>> unlock_bus ops in the adapter. These funcs/ops take an additional flags
>> argument that indicates for what purpose the adapter is locked.
>>
>> There are two flags, I2C_LOCK_ADAPTER and I2C_LOCK_SEGMENT, but they are
>> both implemented the same. For now. Locking the adapter means that the
>> whole bus is locked, locking the segment means that only the current bus
>> segment is locked (i.e. i2c traffic on the parent side of mux is still
>> allowed even if the child side of the mux is locked.
>>
>> Also support a trylock_bus op (but no function to call it, as it is not
>> expected to be needed outside of the i2c core).
>>
>> Implement i2c_lock_adapter/i2c_unlock_adapter in terms of the new locking
>> scheme (i.e. lock with the I2C_LOCK_ADAPTER flag).
>>
>> Annotate some of the locking with explicit I2C_LOCK_SEGMENT flags.
>>
>> Signed-off-by: Peter Rosin <peda@...ntia.se>
> Letting you know that I start reviewing the 2nd part of your series. Did
> the first glimpse today. Will hopefully do the in-depth part this
> weekend. One thing already:
>
>> +static void i2c_adapter_lock_bus(struct i2c_adapter *adapter, int flags)
> Shouldn't flags be unsigned?
>

Yes, obviously... I'll make that change locally and wait for the rest.

Cheers,
Peter