Hi Vladimir, (CC'ing Wolfram) On Friday, 12 October 2018 10:32:32 EEST Vladimir Zapolskiy wrote: > On 10/12/2018 09:04 AM, Lee Jones wrote: > > On Tue, 09 Oct 2018, Vladimir Zapolskiy wrote: > >> From: Vladimir Zapolskiy <vladimir_zapolskiy@xxxxxxxxxx> > >> > >> The change adds TI DS90Ux9xx I2C bridge/alias subdevice driver and > >> FPD Link connection handling mechanism. > >> > >> Access to I2C devices connected to a remote de-/serializer is done in > >> a transparent way, on established link detection event such devices > >> are registered on an I2C bus, which serves a local de-/serializer IC. > >> > >> The development of the driver was a collaborative work, the > >> contribution done by Balasubramani Vivekanandan includes: > >> * original simplistic implementation of the driver, > >> * support of implicitly specified devices in device tree, > >> * support of multiple FPD links for TI DS90Ux9xx, > >> * other kind of valuable review comments, clean-ups and fixes. > >> > >> Also Steve Longerbeam made the following changes: > >> * clear address maps after linked device removal, > >> * disable pass-through in disconnection, > >> * qualify locked status with non-zero remote address. > >> > >> Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@xxxxxxxxxx> > >> --- > >> > >> drivers/mfd/Kconfig | 8 + > >> drivers/mfd/Makefile | 1 + > >> drivers/mfd/ds90ux9xx-i2c-bridge.c | 764 +++++++++++++++++++++++++++++ > >> 3 files changed, 773 insertions(+) > >> create mode 100644 drivers/mfd/ds90ux9xx-i2c-bridge.c > > > > Shouldn't this live in drivers/i2c? > > no, the driver is not for an I2C controller of any kind, and the driver does > not register itself in the I2C subsystem by calling i2c_add_adapter() or > i2c_add_numbered_adapter() or i2c_mux_add_adapter() etc, this topic was > discussed with Wolfram also. (Who is now on CC) > Formally the driver converts the managed IC into a multi-address I2C > slave device, I understand that it does not sound like a well suited driver > for MFD, but ds90ux9xx-core.c and ds90ux9xx-i2c-bridge.c drivers are quite > tightly coupled. As mentioned in other e-mails in this thread I don't think this should be split out to a separate driver, I would move the functionality to the ds90ux9xx driver. You may want to register an I2C mux, but as you have a single port, that could be overkill. I haven't studied in details how to best support this chip using the existing I2C subsystems APIs (which we may want to extend if it needed), but I believe that (in your use cases) the deserializer should be a child of the serializer, and modeled as an I2C device. -- Regards, Laurent Pinchart
