2016-07-25 16:15 GMT+02:00 Thierry Reding <thierry.reding@xxxxxxxxx>: > On Mon, Jul 25, 2016 at 03:16:28PM +0200, Mirza Krak wrote: >> 2016-07-25 13:30 GMT+02:00 Thierry Reding <thierry.reding@xxxxxxxxx>: >> > >> > I would've expected this to require some sort of infrastructure to allow >> > devices connected to the GMI controller to acquire the bus via some API >> > to select their chip. >> >> Yes, ultimately you would need some sort of infrastructure to allow >> devices to acquire the GMI bus if you want to solve this in software. >> But at the moment I do not see such an infrastructure in place, and is >> it feasible to add one specifically for the GMI controller? If one >> such infrastructure was in place we would need to modify all the >> drivers that want to use to include Tegra specific infrastructure to >> access the GMI bus? >> >> Since my knowledge is limited it hard for me to comment on this, maybe >> there is a simple way of doing this? > > I don't think there's a simple way to do this. In order to properly > implement it we'd need to implement a generic infrastructure for chip > selects so that drivers such as the one for your CAN controller can be > written without tying them specifically to the Tegra GMI controller. > > From what you and Jon were saying it sounds like the drivers are > completely agnostic of any chip-select, so conversion won't be easy. > But technically if these chips take a chip-select as input then it's > always possible to hook them up to a controller that doesn't do this > automatic translation of address to chip-select, so eventually some > setup is bound to come along where they'd need explicit chip-select > handling as well. > > I don't think it's fair to require you to implement this infrastructure > if you don't actually need it. At the same time I want to be cautious > and make sure we keep the driver and binding flexible enough to allow > us to implement explicit chip-selects should we later need them. > > Thierry One thing that should be noted, and that is the GMI controller also supports a DMA master mode (feature for the future?). I do not really know how this effects the binding we are discussing but wanted to put it out there. Best Regards, Mirza -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
