Messages in this thread | | | Date | Fri, 1 Sep 2023 10:10:03 +0100 | From | Jonathan Cameron <> | Subject | Re: [PATCH v9 02/15] cxl/regs: Prepare for multiple users of register mappings |
| |
On Thu, 31 Aug 2023 11:11:40 -0700 Dan Williams <dan.j.williams@intel.com> wrote:
> Terry Bowman wrote: > > From: Robert Richter <rrichter@amd.com> > > > > The function devm_cxl_iomap_block() is used to map register mappings > > of CXL component or device registers. A @dev is used to unmap the IO > > regions during device removal. > > > > Now, there are multiple devices using the register mappings. E.g. the > > RAS cap of the Component Registers is used by cxl_pci, the HDM cap > > used in cxl_mem. This could cause IO blocks not being freed and a > > subsequent reinitialization to fail if the same device is used for > > both. > > > > To prevent that, expand cxl_map_component_regs() to pass a @dev to be > > used with devm to IO unmap. This allows to pass the device that > > actually is creating and using the IO region. > > > > For symmetry also change the function i/f of cxl_map_device_regs(). > > I think @dev is too ambiguous as a name. I.e. when does @dev refer to > the 'struct device *' instance that the registers belong, and when does > @dev refer to the 'struct device *' instance hosting the mapping for > devm operations? > > One of the ways I have tried to disambiguate that distinction is using > the name @host to explicitly refer to the context of devm operations, > and @dev is only for context for dev_dbg() operations. Can you clarify > this patch by using @host everywhere that the devm context is being > handled? > > This would also satisfy Jonathan's concern. I think it needs to be the > case that @map is explicit about when it is conveying some @dev context for > dev_dbg() messages and when it is conveying the @host for devm > operations because those are 2 different concepts.
I should read all the replies before I reply to any of them. Agreed that renaming it would satisfy my concern over the confusion.
> > It looks like @dev argument you are plumbing here is for when @map->dev > cannot be used for devm operations, so at a minimum use @host as the > variable name to make that clear... > > ...or always make it the case that @map carries an @host parameter which > would mean that ports would need their own copy of the comp_map versus > directly reusing the one in the cxlds since those 2 mapping instances > need different @host parameters. That feels cleaner to me then > "sometimes map->dev can be used for devm and sometimes not". @map->host > is always the devm context.
Agreed that may be better still.
Jonathan
| |