|
From: | Igor Mitsyanko |
Subject: | Re: [Qemu-devel] [PATCH V2 1/3] exynos4210: add Exynos4210 i2c implementation |
Date: | Wed, 21 Mar 2012 17:07:02 +0400 |
User-agent: | Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.27) Gecko/20120216 Thunderbird/3.1.19 |
On 03/21/2012 03:55 PM, Peter Maydell wrote:
On 15 March 2012 07:35, Igor Mitsyanko<address@hidden> wrote:Create 9 exynos4210 i2c interfaces. Signed-off-by: Igor Mitsyanko<address@hidden>Mostly this looks OK but I still find the i2c slave stuff odd -- should the controller really register itself as a slave on its own bus? Doesn't this mean that the controller can effectively try to talk to itself? Does the hardware let you do that?
Controller's master and slave i2c interfaces operate on the same single bus, so I think it should. It can't talk to itself because controller's two modes of operation are mutually exclusive. As I said, I took this approach from pxa i2c implementation, the only difference is that they register slave interface on a separate bus, but I think it's not right to do that.
I suspect that what's happening here is that the hardware lets you put the i2c controller into slave mode so some other device on the bus can be a master. But QEMU's i2c bus abstraction doesn't cover that use case at all...
Yes, I saw this statement in hw/i2c.h (and probably cpu i2c controller will never be used as i2c slave device by anyone), but I think we still have to implement devices exactly like they described in documentation.
-- Mitsyanko Igor ASWG, Moscow R&D center, Samsung Electronics email: address@hidden
[Prev in Thread] | Current Thread | [Next in Thread] |