From: Vladimir Zapolskiy <vz@mleia.com> To: jacopo mondi <jacopo@jmondi.org>, Luca Ceresoli <luca@lucaceresoli.net>, Wolfram Sang <wsa@the-dreams.de>, Peter Rosin <peda@axentia.se> Cc: linux-media@vger.kernel.org, linux-i2c@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Mauro Carvalho Chehab <mchehab@kernel.org>, Rob Herring <robh+dt@kernel.org>, Mark Rutland <mark.rutland@arm.com>, Sakari Ailus <sakari.ailus@linux.intel.com>, Hans Verkuil <hverkuil-cisco@xs4all.nl>, Laurent Pinchart <laurent.pinchart@ideasonboard.com>, Kieran Bingham <kieran.bingham@ideasonboard.com> Subject: Re: [RFC,v2 2/6] i2c: add I2C Address Translator (ATR) support Date: Mon, 9 Sep 2019 07:56:22 +0300 Message-ID: <1fb71437-eaa2-99a7-885f-63ee769969aa@mleia.com> (raw) In-Reply-To: <aedad45b-16d6-d189-b045-329727440ca5@mleia.com> Hi Luca, Jacopo, Wolfram, Peter, On 09/08/2019 11:45 PM, Vladimir Zapolskiy wrote: > Hi Luca, Jacopo, Wolfram, Peter, > > On 09/01/2019 05:31 PM, jacopo mondi wrote: >> Hi Luca, >> thanks for keep pushing this series! I hope we can use part of this >> for the (long time) on-going GMSL work... >> >> I hope you will be patient enough to provide (another :) overview >> of this work during the BoF Wolfram has organized at LPC for the next >> week. >> >> In the meantime I would have some comments after having a read at the >> series and trying to apply its concept to GMSL >> > > I won't attend the LPC, however I would appreciate if you book some > time to review my original / alternative implementation of the TI > DS90Ux9xx I2C bridge device driver. > > For your convenience the links to the driver are given below: > * dt bindings: https://lore.kernel.org/lkml/20181012060314.GU4939@dell/T/#mead5ea226550b > * driver code: https://lore.kernel.org/lkml/20181012060314.GU4939@dell/T/#m2fe3664c5f884 > * usage example: https://lore.kernel.org/lkml/20181012060314.GU4939@dell/T/#m56c146f5decdc > > The reasons why my driver is better/more flexible/more functional are > discussed earlier, please let me know, if you expect anything else > from me to add, also I would be happy to get a summary of your offline > discussion. I forgot to repeat my main objection against Luca's approach, the TI DS90Ux9xx I2C bridge driver does not require to call i2c_add_adapter() or register a new mux/bus and then do run select/deselect in runtime to overcome the created handicap. > The undeniable fact is that the device tree bindings in my I2C bridge > implementation can be improved further, thanks to Luca for the comments. > >> On Tue, Jul 23, 2019 at 10:37:19PM +0200, Luca Ceresoli wrote: >>> An ATR is a device that looks similar to an i2c-mux: it has an I2C >>> slave "upstream" port and N master "downstream" ports, and forwards >>> transactions from upstream to the appropriate downstream port. But is >>> is different in that the forwarded transaction has a different slave >>> address. The address used on the upstream bus is called the "alias" >>> and is (potentially) different from the physical slave address of the >>> downstream chip. >>> >>> Add a helper file (just like i2c-mux.c for a mux or switch) to allow >>> implementing ATR features in a device driver. The helper takes care or >>> adapter creation/destruction and translates addresses at each transaction. >>> >>> Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net> >>> > -- Best wishes, Vladimir
next prev parent reply index Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-07-23 20:37 [RFC,v2 0/6] TI camera serdes and I2C address translation Luca Ceresoli 2019-07-23 20:37 ` [RFC,v2 1/6] i2c: core: let adapters be notified of client attach/detach Luca Ceresoli 2019-07-23 20:37 ` [RFC,v2 2/6] i2c: add I2C Address Translator (ATR) support Luca Ceresoli 2019-09-01 14:31 ` jacopo mondi 2019-09-03 7:31 ` Luca Ceresoli 2019-09-03 7:37 ` Wolfram Sang 2019-09-04 8:09 ` Peter Rosin 2019-09-08 19:40 ` Luca Ceresoli 2019-09-10 18:46 ` Wolfram Sang 2019-09-08 20:45 ` Vladimir Zapolskiy 2019-09-09 4:56 ` Vladimir Zapolskiy [this message] 2019-09-10 17:40 ` Luca Ceresoli 2019-09-09 7:22 ` Wolfram Sang 2019-09-09 15:10 ` Vladimir Zapolskiy 2019-09-09 17:48 ` Luca Ceresoli 2019-09-10 17:16 ` Wolfram Sang 2019-09-02 20:42 ` Wolfram Sang 2019-09-03 8:48 ` Luca Ceresoli 2019-09-03 9:06 ` Wolfram Sang 2019-07-23 20:37 ` [RFC,v2 3/6] media: dt-bindings: add DS90UB954-Q1 video deserializer Luca Ceresoli 2019-08-13 15:44 ` Rob Herring 2019-08-19 22:41 ` Luca Ceresoli 2019-08-20 15:44 ` Rob Herring 2019-08-21 21:50 ` Luca Ceresoli 2019-09-02 20:48 ` Wolfram Sang 2019-09-03 9:09 ` Luca Ceresoli 2019-09-03 9:34 ` Wolfram Sang 2019-09-03 11:03 ` Luca Ceresoli 2019-09-03 14:16 ` Wolfram Sang 2019-09-10 9:43 ` Sakari Ailus 2019-09-10 15:02 ` Luca Ceresoli 2019-07-23 20:37 ` [RFC,v2 4/6] media: dt-bindings: add DS90UB953-Q1 video serializer Luca Ceresoli 2019-07-23 20:37 ` [RFC,v2 5/6] media: ds90ub954: new driver for TI DS90UB954-Q1 video deserializer Luca Ceresoli 2019-07-23 20:37 ` [RFC,v2 6/6] media: ds90ub953: new driver for TI DS90UB953-Q1 video serializer Luca Ceresoli
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