| Message ID | 20150225172757.421.43718@quantum (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Feb 25, 2015 at 09:27:57AM -0800, Mike Turquette wrote: > Quoting Shawn Guo (2015-02-25 06:53:31) > > Since commit 035a61c314eb ("clk: Make clk API return per-user struct clk > > instances"), clk API users can no longer check if two struct clk > > pointers are pointing to the same hardware clock, i.e. struct clk_hw, by > > simply comparing two pointers. That's because with the per-user clk > > change, a brand new struct clk is created whenever clients try to look > > up the clock by calling clk_get() or sister functions like clk_get_sys() > > and of_clk_get(). This changes the original behavior where the struct > > clk is only created for once when clock driver registers the clock to > > CCF in the first place. The net change here is before commit > > 035a61c314eb the struct clk pointer is unique for given hardware > > clock, while after the commit the pointers returned by clk lookup calls > > become different for the same hardware clock. > > > > A number of client drivers detecting if two struct clk pointers point to > > the same one hardware clock by comparing the pointers are broken now. > > As a stop-gap solution, this patch adds a helper function clk_is_match() > > to test if two struct clk pointers point to the same hardware clock, so > > that these client drivers can use to fix the regression. > > > > Signed-off-by: Shawn Guo <shawn.guo@linaro.org> > > Hi Shawn, > > Thanks for the patch. I wrote a similar one last night but did not > finish fixing up the drivers (and thus did not post it). I prefer my > implementation below, and I'm happy to merge your driver fixes with it. > > Regards, > Mike > > > > From: Michael Turquette <mturquette@linaro.org> > Date: Wed, 25 Feb 2015 09:11:01 -0800 > Subject: [PATCH] clk: introduce clk_is_match > > Some drivers compare struct clk pointers as a means of knowing > if the two pointers reference the same clock hardware. This behavior is > dubious (drivers must not dereference struct clk), but did not cause any > regressions until the per-user struct clk patch was merged. Now the test > for matching clk's will always fail with per-user struct clk's. > > clk_is_match is introduced to fix the regression and prevent drivers > from comparing the pointers manually. small observaton, clk_is_same() is linguistically nicer.
Am Donnerstag, den 26.02.2015, 09:02 +0000 schrieb Ben Dooks: > On Wed, Feb 25, 2015 at 09:27:57AM -0800, Mike Turquette wrote: [...] > > From: Michael Turquette <mturquette@linaro.org> > > Date: Wed, 25 Feb 2015 09:11:01 -0800 > > Subject: [PATCH] clk: introduce clk_is_match > > > > Some drivers compare struct clk pointers as a means of knowing > > if the two pointers reference the same clock hardware. This behavior is > > dubious (drivers must not dereference struct clk), but did not cause any > > regressions until the per-user struct clk patch was merged. Now the test > > for matching clk's will always fail with per-user struct clk's. > > > > clk_is_match is introduced to fix the regression and prevent drivers > > from comparing the pointers manually. > > small observaton, clk_is_same() is linguistically nicer. How about clk_equal() ? regards Philipp
On Thu, Feb 26, 2015 at 10:56:58AM +0100, Philipp Zabel wrote: > Am Donnerstag, den 26.02.2015, 09:02 +0000 schrieb Ben Dooks: > > On Wed, Feb 25, 2015 at 09:27:57AM -0800, Mike Turquette wrote: > [...] > > > From: Michael Turquette <mturquette@linaro.org> > > > Date: Wed, 25 Feb 2015 09:11:01 -0800 > > > Subject: [PATCH] clk: introduce clk_is_match > > > > > > Some drivers compare struct clk pointers as a means of knowing > > > if the two pointers reference the same clock hardware. This behavior is > > > dubious (drivers must not dereference struct clk), but did not cause any > > > regressions until the per-user struct clk patch was merged. Now the test > > > for matching clk's will always fail with per-user struct clk's. > > > > > > clk_is_match is introduced to fix the regression and prevent drivers > > > from comparing the pointers manually. > > > > small observaton, clk_is_same() is linguistically nicer. > > How about clk_equal() ? That's good, the only issue that's not clear in any of these names is that does this mean "the same clock", a "clock of the same rate" or a "clock that is equivalent to in the rate and phase but not subject to the same gate".
On Thu, 26 Feb 2015, Ben Dooks wrote: > > > small observaton, clk_is_same() is linguistically nicer. > > > > How about clk_equal() ? > > That's good, the only issue that's not clear in any of these names is > that does this mean "the same clock", a "clock of the same rate" or a > "clock that is equivalent to in the rate and phase but not subject to > the same gate". clk_identical() ? /Ricard
On Wed, Feb 25, 2015 at 6:27 PM, Mike Turquette <mturquette@linaro.org> wrote: > From: Michael Turquette <mturquette@linaro.org> > Date: Wed, 25 Feb 2015 09:11:01 -0800 > Subject: [PATCH] clk: introduce clk_is_match > > Some drivers compare struct clk pointers as a means of knowing > if the two pointers reference the same clock hardware. This behavior is > dubious (drivers must not dereference struct clk), but did not cause any > regressions until the per-user struct clk patch was merged. Now the test > for matching clk's will always fail with per-user struct clk's. > > clk_is_match is introduced to fix the regression and prevent drivers > from comparing the pointers manually. > > Fixes: 035a61c314eb ("clk: Make clk API return per-user struct clk instances") > Cc: Russell King <linux@arm.linux.org.uk> > Cc: Stephen Boyd <sboyd@codeaurora.org> > Cc: Shawn Guo <shawn.guo@linaro.org> > Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com> > Signed-off-by: Michael Turquette <mturquette@linaro.org> > --- > drivers/clk/clk.c | 26 ++++++++++++++++++++++++++ > include/linux/clk.h | 18 ++++++++++++++++++ > 2 files changed, 44 insertions(+) > > diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c > index eb01529..09670de 100644 > --- a/drivers/clk/clk.c > +++ b/drivers/clk/clk.c > @@ -2171,6 +2171,32 @@ int clk_get_phase(struct clk *clk) > } > > /** > + * clk_is_match - check if two clk's point to the same hardware clock > + * @p: clk compared against q > + * @q: clk compared against p > + * > + * Returns true if the two struct clk pointers both point to the same hardware > + * clock node. Put differently, returns true if struct clk *p and struct clk *q > + * share the same struct clk_core object. > + * > + * Returns false otherwise. Note that two NULL clks are treated as matching. > + */ > +bool clk_is_match(struct clk *p, struct clk *q) const struct clk *p, const struct clk *q > --- a/include/linux/clk.h > +++ b/include/linux/clk.h > @@ -376,6 +376,19 @@ struct clk *clk_get_parent(struct clk *clk); > */ > struct clk *clk_get_sys(const char *dev_id, const char *con_id); > > +/** > + * clk_is_match - check if two clk's point to the same hardware clock > + * @p: clk compared against q > + * @q: clk compared against p > + * > + * Returns true if the two struct clk pointers both point to the same hardware > + * clock node. Put differently, returns true if struct clk *p and struct clk *q > + * share the same struct clk_core object. > + * > + * Returns false otherwise. Note that two NULL clks are treated as matching. > + */ > +bool clk_is_match(struct clk *p, struct clk *q); const struct clk *p, const struct clk *q > + > #else /* !CONFIG_HAVE_CLK */ > > static inline struct clk *clk_get(struct device *dev, const char *id) > @@ -429,6 +442,11 @@ static inline struct clk *clk_get_parent(struct clk *clk) > return NULL; > } > > +static inline bool clk_is_match(struct clk *p, struct clk *q) const struct clk *p, const struct clk *q > +{ > + return p == q ? true : false; Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
On Wed, Feb 25, 2015 at 09:27:57AM -0800, Mike Turquette wrote: > +static inline bool clk_is_match(struct clk *p, struct clk *q) > +{ > + return p == q ? true : false; When they created the C standard, they already taught the compiler that p == q returns a true / false boolean value; there's no need for ?: here.
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index eb01529..09670de 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -2171,6 +2171,32 @@ int clk_get_phase(struct clk *clk) } /** + * clk_is_match - check if two clk's point to the same hardware clock + * @p: clk compared against q + * @q: clk compared against p + * + * Returns true if the two struct clk pointers both point to the same hardware + * clock node. Put differently, returns true if struct clk *p and struct clk *q + * share the same struct clk_core object. + * + * Returns false otherwise. Note that two NULL clks are treated as matching. + */ +bool clk_is_match(struct clk *p, struct clk *q) +{ + /* trivial case: identical struct clk's or both NULL */ + if (p == q) + return true; + + /* true if clk->core pointers match. Avoid derefing garbage */ + if (!IS_ERR_OR_NULL(p) && !IS_ERR_OR_NULL(q)) + if (p->core == q->core) + return true; + + return false; +} +EXPORT_SYMBOL_GPL(clk_is_match); + +/** * __clk_init - initialize the data structures in a struct clk * @dev: device initializing this clk, placeholder for now * @clk: clk being initialized diff --git a/include/linux/clk.h b/include/linux/clk.h index 8381bbf..5c076e4 100644 --- a/include/linux/clk.h +++ b/include/linux/clk.h @@ -376,6 +376,19 @@ struct clk *clk_get_parent(struct clk *clk); */ struct clk *clk_get_sys(const char *dev_id, const char *con_id); +/** + * clk_is_match - check if two clk's point to the same hardware clock + * @p: clk compared against q + * @q: clk compared against p + * + * Returns true if the two struct clk pointers both point to the same hardware + * clock node. Put differently, returns true if struct clk *p and struct clk *q + * share the same struct clk_core object. + * + * Returns false otherwise. Note that two NULL clks are treated as matching. + */ +bool clk_is_match(struct clk *p, struct clk *q); + #else /* !CONFIG_HAVE_CLK */ static inline struct clk *clk_get(struct device *dev, const char *id) @@ -429,6 +442,11 @@ static inline struct clk *clk_get_parent(struct clk *clk) return NULL; } +static inline bool clk_is_match(struct clk *p, struct clk *q) +{ + return p == q ? true : false; +} + #endif /* clk_prepare_enable helps cases using clk_enable in non-atomic context. */