On Fri, Nov 17, 2023 at 08:30:21PM +0800, Inochi Amaoto wrote: > > > >On 17/11/2023 06:07, Inochi Amaoto wrote: > >> The timer registers of aclint don't follow the clint layout and can > >> be mapped on any different offset. As sg2042 uses separated timer > >> and mswi for its clint, it should follow the aclint spec and have > >> separated registers. > >> > >> The previous patch introduced a new type of T-HEAD aclint timer which > >> has clint timer layout. Although it has the clint timer layout, it > >> should follow the aclint spec and uses the separated mtime and mtimecmp > >> regs. So a ABI change is needed to make the timer fit the aclint spec. > >> > >> To make T-HEAD aclint timer more closer to the aclint spec, use > >> regs-names to represent the mtimecmp register, which can avoid hack > >> for unsupport mtime register of T-HEAD aclint timer. > >> > > > >I don't understand this reasoning. You had one entry, you still have one > >entry. Adding reg-names (not regs-names) does not change it. > > > > If no "reg-names", all the register of ACLINT should be defined. However, > T-HEAD aclint timer of sg2042 only supports mtimecmp register. If no extra > prompt is provided for the SBI, it will fail to recognize aclint timer > registers when parsing the aclint node with one reg entry. > > There is another way to avoid this by using an empty entry to identify > unsupported mtime, but Conor have already rejected this. See [1]. > > Link: https://lore.kernel.org/all/20231114-skedaddle-precinct-66c8897227bb@squawk/ [1] Perhaps you misunderstood my suggestion. I was looking for _both_ registers to be defined in the binding as well as adding reg-names as a required property. Doing what you have here might work for your use case, but does not make sense from a bindings point of view as there is no way to describe the mtime register, should it exist in another SoC. Cheers, Conor
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