On Wed, Aug 8, 2018 at 11:30 AM Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx> wrote: > > Hi Rob, > > On Tue, Aug 07, 2018 at 12:47:10PM -0600, Rob Herring wrote: > > On Mon, Jul 30, 2018 at 08:41:31PM +0530, Manivannan Sadhasivam wrote: > > > Hi Andreas, > > > > > > On Mon, Jul 30, 2018 at 12:26:07PM +0200, Andreas Färber wrote: > > > > Hi Mani, > > > > > > > > Am 27.07.2018 um 20:45 schrieb Manivannan Sadhasivam: > > > > > This patchset adds Reset Controller (RMU) support for Actions Semi > > > > > Owl SoCs, S900 and S700. For the Owl SoCs, RMU has been integrated into > > > > > the clock subsystem in hardware. Hence, in software we integrate RMU > > > > > support into common clock driver inorder to maintain compatibility. > > > > > > > > Can this not be placed into drivers/reset/ by using mfd-simple with a > > > > sub-node in DT? > > > > That is exactly what I tell folks not to do. Design the DT based on h/w > > blocks, not current desired driver split for some OS. > > > > > Actually I was not sure where to place this reset controller driver. When I > > > looked into other similar ones such as sunxi, they just integrated into the > > > clk subsystem. So I just chose that path. But yeah, this is hacky! > > > > > > But this RMU is not MFD by any means. Since the CMU (Clock) and RMU (Reset) > > > are two separate IPs inside SoC, we shouldn't describe it as a MFD driver. Since > > > RMU has only 2 registers, the HW designers decided to use up the CMU memory > > > map. So, maybe syscon would be best option I think. What is your opinion? > > > > If there's nothing shared then it is not a syscon. If you can create > > separate address ranges, then 2 nodes is probably okay. If the registers > > are all mixed up, then 1 node. > > > > I don't quite understand the reason for not being syscon. The definition > of syscon says that, "System controller node represents a register region > containing a set of miscellaneous registers. The registers are not cohesive > enough to represent as any specific type of device." which exactly fits > this case. Only the registers of CMU & RMU are shared and not the HW block! > > Can you please clarify? IIRC, the original intent of 'syscon' was really for things that had no subsystem. Random bits all just dumped together. A block with clock and reset doesn't sounds pretty well defined functions. Plus that criteria doesn't work well because what does and doesn't have a subsystem (and DT binding) evolves. IMO, we should probably get rid of 'syscon'. Let me turn it around. Why do you want it do be a syscon? Simply to create a regmap I suppose because that is all that 'syscon' compatible is. A flag to create a regmap. Why do you need a regmap then? Do you need to protect concurrent accesses (a single register has both clock and reset bits). If so, you can't really call CMU and RMU 2 blocks. If not, you don't really need regmap. Rob -- 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
