> And I can define acpi_free_buffer() in the Linux-specific code too. > > Thanks, > Rafael I'll be glad to add an ACPI_FREE_BUFFER macro, although we've had complaints over the years that ACPICA uses too many macros. (Not so many complaints in the last 5 years, however.) Bob > -----Original Message----- > From: Rafael J. Wysocki [mailto:rjw@xxxxxxx] > Sent: Wednesday, November 14, 2012 1:33 AM > To: Moore, Robert > Cc: Mika Westerberg; mathias.nyman@xxxxxxxxxxxxxxx; linux- > acpi@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; lenb@xxxxxxxxxx; > Wysocki, Rafael J; broonie@xxxxxxxxxxxxxxxxxxxxxxxxxxx; > grant.likely@xxxxxxxxxxxx; linus.walleij@xxxxxxxxxx; khali@xxxxxxxxxxxx; > Bjorn Helgaas; Zheng, Lv > Subject: Re: [PATCH 3/3] ACPI: Evaluate _CRS while creating device node > objects > > On Wednesday, November 14, 2012 10:18:46 AM Rafael J. Wysocki wrote: > > On Wednesday, November 14, 2012 02:23:51 AM Moore, Robert wrote: > > > Rafael, > > > > > > I sounds like with a few changes, we can enhance this mechanism to > > > be more useful to you and others. Some comments below. I need to > > > look at the code in question a bit more, but I see no insurmountable > issues. > > > > Great, thanks! > > > > > > > > -----Original Message----- > > > > From: Rafael J. Wysocki [mailto:rjw@xxxxxxx] > > > > Sent: Tuesday, November 13, 2012 2:57 PM > > > > To: Moore, Robert > > > > Cc: Mika Westerberg; mathias.nyman@xxxxxxxxxxxxxxx; linux- > > > > acpi@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > > > > lenb@xxxxxxxxxx; Wysocki, Rafael J; > > > > broonie@xxxxxxxxxxxxxxxxxxxxxxxxxxx; > > > > grant.likely@xxxxxxxxxxxx; linus.walleij@xxxxxxxxxx; > > > > khali@xxxxxxxxxxxx; Bjorn Helgaas; Zheng, Lv > > > > Subject: Re: [PATCH 3/3] ACPI: Evaluate _CRS while creating device > > > > node objects > > > > > > > > On Tuesday, November 13, 2012 10:06:03 PM Moore, Robert wrote: > > > > > I may not quite understand what you are asking for, but I will > try. > > > > > It seems like we already have much of what you want/need, so > > > > > maybe I'm missing something. > > > > > > > > I think all of the necessary pieces are there. > > > > > > > > > > So what I would like to have, in general terms, is something > > > > > > like > > > > > > acpi_walk_resources() split into three parts: > > > > > > > > > > > > (1) One that processes the _CRS output and creates a list of > > > > > > struct acpi_resource objects for us to play with. I > suppose > > > > > > it's OK if that's just a buffer filled with resource > objects, > > > > > > but a linked list might be more convenient. > > > > > > > > > > > > > > > > This sounds like AcpiGetCurrentResources. It executes _CRS and > > > > > formats the data into acpi_resource objects. > > > > > > > > Yes, it does. However, it is not completely clear to me if/how > > > > the caller is supposed to prepare the buffer object pointed to by > the second arg. > > > > > > > > If the buffer is initialized by AcpiGetCurrentResources, then > > > > that's what I need for (1). > > > > > > > > > It looks to me that at least AcpiGetCurrentResources does not > > > actually ever allocate a buffer for the resource template, it > > > expects the caller to eventually provide one of at least the size of > the returned resource template. > > > > > > This is really quite a bit out-of-date as far as the memory allocation > model. > > > It should also support the option to just allocate the buffer of the > > > appropriate size before returning it to the caller. > > > > Yes, that would be really useful. > > > > Ideally, I'd like to be able to pass a pointer to an uninitialized > > buffer structure to it (or to a wrapper around it) and get a buffer > > full of struct acpi_resource objects (if _CRS returns any) back from > > it. :-) > > Of course, I can add such a wrapper in the Linux-specific code just fine. > > > > > > > > (2) One that allows us to access (read/write) resources in the > > > > > > list returned by (1). We don't need to open code walking > > > > > > the list and I probably wouldn't event want to do that. > What > > > > > > we need is to be able to walk the same list for a number of > > > > > > times and possibly to modify values in the resource objects > > > > > > if there are conflicts. > > > > > > > > > > This sounds like AcpiWalkResources. I suppose a possible issue > > > > > is that currently, AcpiWalkResources actually invokes the _CRS, > > > > > _PRS, or _AEI method on behalf of the caller. > > > > > > > > Yes, that exactly is the problem. > > > > > > > > > It might make more sense to allow the caller to pass in the > > > > > resource buffer returned from a call to _CRS, etc. > > > > > > > > Yes! :-) > > > > > > > > > I'll take a closer look at this tomorrow. > > > > Cool, thanks! > > > > > > > > > > (3) One allowing us to free the list returned by (1) if not > needed > > > > > > any more. > > > > > > > > > > > > > > > > AcpiGetCurrentResources: Currently, everything is returned in a > > > > > single buffer to minimize the number of allocations. A buffer > > > > > you can free when you are done with it. > > > > > > > > I suppose I should use ACPI_FREE(buffer.pointer) for that, but > > > > isn't it for the ACPICA's internal use only? > > > > > > > > Besides, I would prefer to be able to pass just "buffer" for > > > > freeing, without having to touch its internals. No big deal, but > > > > it would be nicer. :-) > > > > > > > > > The ACPI_BUFFER type is in fact a public type that is meant to > > > return both the buffer and the (actual) length. You will find many > > > instances of > > > ACPI_FREE(buffer.pointer) within existing linux code, since it also > > > used for objects returned by control method execution/object > evaluation. > > > > Well, I suppose I only wanted to say that acpi_free_buffer(buffer) > > would look a bit more straightforward than ACPI_FREE(buffer.pointer). > > :-) > > And I can define acpi_free_buffer() in the Linux-specific code too. > > Thanks, > Rafael > > > -- > I speak only for myself. > Rafael J. 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