* Re: [PATCH 1/3] resource: Add resource set range and size helpers
2024-06-13 13:28 ` [PATCH 1/3] resource: Add resource set range and size helpers Jonathan Cameron
@ 2024-06-13 13:55 ` Ilpo Järvinen
0 siblings, 0 replies; 2+ messages in thread
From: Ilpo Järvinen @ 2024-06-13 13:55 UTC (permalink / raw)
To: Jonathan Cameron
Cc: Bjorn Helgaas, linux-pci, Lorenzo Pieralisi, Rob Herring,
Krzysztof Wilczyński, LKML, Jonathan Hunter,
linux-arm-kernel, linux-tegra, Robert Richter, Thierry Reding,
linux-cxl
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On Thu, 13 Jun 2024, Jonathan Cameron wrote:
> On Wed, 12 Jun 2024 11:56:27 +0300
> Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> wrote:
>
> > Setting the end address for a resource with a given size lacks a helper
> > and is therefore open coded unlike the getter side which has a helper
> > for resource size calculation. Also, almost all callsites that
> > calculate end address for a resource also set the start address right
> > before it like this:
> >
> > res->start = start_addr;
> > res->end = res->start + size - 1;
> >
> > Thus, add resource_set_range(res, start_addr, size) that sets the start
> > address and calculates the end address to simplify this often repeated
> > fragment. In addition, introduce resource_set_size() for the cases
> > where setting the start address of the resource is not necessary but
> > note resource_set_range() is preferred.
> >
> > Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
>
> We have a bunch of cases of this in CXL. Adding this helper seems like
> a good idea to me.
Sadly this won't help struct range cases which feature the same math.
> I'm not sure the odd semantics of resource_set_size() are a good idea.
> Maybe it could by naming hint that it's relying internally on
> size already being set.
>
> resource_update_size() for instance might make people think or perhaps
> that's just more obscure. Meh, I've argued myself around to there
> not being a better name.
Yeah, I tried to figure out solution to this very challenge too, but alas,
couldn't really find any good solution to it.
__ prefix would have kind of conveyed the meaning that you better know
what you're doing but as some people oppose __ too, I didn't want to stir
that pot. So it is what it is.
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>`
FYI, I dropped the extra ` from that (no need to reply because of it).
Thanks for the reviews.
--
i.
> > ---
> > include/linux/ioport.h | 32 ++++++++++++++++++++++++++++++++
> > 1 file changed, 32 insertions(+)
> >
> > diff --git a/include/linux/ioport.h b/include/linux/ioport.h
> > index db7fe25f3370..2a1d33ad151c 100644
> > --- a/include/linux/ioport.h
> > +++ b/include/linux/ioport.h
> > @@ -216,6 +216,38 @@ struct resource *lookup_resource(struct resource *root, resource_size_t start);
> > int adjust_resource(struct resource *res, resource_size_t start,
> > resource_size_t size);
> > resource_size_t resource_alignment(struct resource *res);
> > +
> > +/**
> > + * resource_set_size - Calculates resource end address from size and start address
> > + * @res: The resource descriptor
> > + * @size: The size of the resource
> > + *
> > + * Calculates the end address for @res based on @size.
> > + *
> > + * Note: The start address of @res must be set when calling this function.
> > + * Use resource_set_range() if setting both the start address and @size.
> > + */
> > +static inline void resource_set_size(struct resource *res, resource_size_t size)
> > +{
> > + res->end = res->start + size - 1;
> > +}
> > +
> > +/**
> > + * resource_set_range - Sets resource start and end addresses
> > + * @res: The resource descriptor
> > + * @start: The start address for the resource
> > + * @size: The size of the resource
> > + *
> > + * Sets @res start address and calculates the end address based on @size.
> > + */
> > +static inline void resource_set_range(struct resource *res,
> > + resource_size_t start,
> > + resource_size_t size)
> > +{
> > + res->start = start;
> > + resource_set_size(res, size);
> > +}
> > +
> > static inline resource_size_t resource_size(const struct resource *res)
> > {
> > return res->end - res->start + 1;
>
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