| Message ID | 20230613083626.227476-3-frank@oltmanns.dev (mailing list archive) |
|---|---|
| State | Changes Requested, archived |
| Headers | show |
| Series | clk: fractional-divider: Improve approximation when zero based | expand |
Hi Stephen, On 2023-06-13 at 10:36:26 +0200, Frank Oltmanns <frank@oltmanns.dev> wrote: > In light of the recent discovery that the fractional divisor > approximation does not utilize the full available range for clocks that > are flagged CLK_FRAC_DIVIDER_ZERO_BASED, implement tests for the edge > cases of this clock type. > > Signed-off-by: Frank Oltmanns <frank@oltmanns.dev> > Link: https://lore.kernel.org/lkml/20230529133433.56215-1-frank@oltmanns.dev > --- > drivers/clk/clk_test.c | 69 +++++++++++++++++++++++++++++++++++++++++- > 1 file changed, 68 insertions(+), 1 deletion(-) > > diff --git a/drivers/clk/clk_test.c b/drivers/clk/clk_test.c > index f9a5c2964c65..b247ba841cbd 100644 > --- a/drivers/clk/clk_test.c > +++ b/drivers/clk/clk_test.c > @@ -8,6 +8,9 @@ > /* Needed for clk_hw_get_clk() */ > #include "clk.h" > > +/* Needed for clk_fractional_divider_general_approximation */ > +#include "clk-fractional-divider.h" > + > #include <kunit/test.h> > > #define DUMMY_CLOCK_INIT_RATE (42 * 1000 * 1000) > @@ -2394,6 +2397,69 @@ static struct kunit_suite clk_mux_notifier_test_suite = { > .test_cases = clk_mux_notifier_test_cases, > }; > > + > +/* > + * Test that clk_fractional_divider_general_approximation will work with the > + * highest available numerator and denominator. > + */ > +static void clk_fd_test_round_rate_max_mn(struct kunit *test) > +{ > + struct clk_fractional_divider *fd; > + struct clk_hw *hw; > + unsigned long rate, parent_rate, m, n; > + > + fd = kunit_kzalloc(test, sizeof(*fd), GFP_KERNEL); > + KUNIT_ASSERT_NOT_NULL(test, fd); > + > + fd->mwidth = 3; > + fd->nwidth = 3; > + > + hw = &fd->hw; > + > + rate = DUMMY_CLOCK_RATE_1; > + > + // Highest denominator, no flags > + parent_rate = 10 * DUMMY_CLOCK_RATE_1; > + clk_fractional_divider_general_approximation(hw, rate, &parent_rate, &m, &n); > + KUNIT_EXPECT_EQ(test, m, 1); > + KUNIT_EXPECT_EQ(test, n, 7); > + > + // Highest numerator, no flags > + parent_rate = DUMMY_CLOCK_RATE_1 / 10; > + clk_fractional_divider_general_approximation(hw, rate, &parent_rate, &m, &n); > + KUNIT_EXPECT_EQ(test, m, 7); > + KUNIT_EXPECT_EQ(test, n, 1); The two calls above aim at proving that the change does not break existing functionality. > + > + // Highest denominator, zero based > + parent_rate = 10 * DUMMY_CLOCK_RATE_1; > + fd->flags = CLK_FRAC_DIVIDER_ZERO_BASED; > + clk_fractional_divider_general_approximation(hw, rate, &parent_rate, &m, &n); > + KUNIT_EXPECT_EQ(test, m, 1); > + KUNIT_EXPECT_EQ(test, n, 8); > + > + // Highest numerator, zero based > + parent_rate = DUMMY_CLOCK_RATE_1 / 10; > + clk_fractional_divider_general_approximation(hw, rate, &parent_rate, &m, &n); > + KUNIT_EXPECT_EQ(test, m, 8); > + KUNIT_EXPECT_EQ(test, n, 1); > +} > + > +static struct kunit_case clk_fd_test_cases[] = { > + KUNIT_CASE(clk_fd_test_round_rate_max_mn), > + {} > +}; > + > +/* > + * Test suite for a fractional divider clock. > + * > + * These tests exercise the fractional divider API: clk_recalc_rate, > + * clk_set_rate(), clk_round_rate(). > + */ > +static struct kunit_suite clk_fd_test_suite = { > + .name = "clk-fd-test", > + .test_cases = clk_fd_test_cases, > +}; Unfortunately, the style of the tests does not really match with the style of the existing tests, because those where all aimed at the framework itself and not at specific functions. Please let me know, if you require any changes. Thanks, Frank > + > kunit_test_suites( > &clk_leaf_mux_set_rate_parent_test_suite, > &clk_test_suite, > @@ -2406,6 +2472,7 @@ kunit_test_suites( > &clk_range_maximize_test_suite, > &clk_range_minimize_test_suite, > &clk_single_parent_mux_test_suite, > - &clk_uncached_test_suite > + &clk_uncached_test_suite, > + &clk_fd_test_suite > ); > MODULE_LICENSE("GPL v2");
Hi Frank,
kernel test robot noticed the following build errors:
[auto build test ERROR on v6.4-rc6]
[also build test ERROR on linus/master]
[cannot apply to clk/clk-next next-20230613]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Frank-Oltmanns/clk-fractional-divider-Improve-approximation-when-zero-based/20230613-163903
base: v6.4-rc6
patch link: https://lore.kernel.org/r/20230613083626.227476-3-frank%40oltmanns.dev
patch subject: [PATCH v2 2/2] clk: tests: Add tests for fractional divisor approximation
config: csky-randconfig-r011-20230612 (https://download.01.org/0day-ci/archive/20230613/202306132038.nUB6hmCv-lkp@intel.com/config)
compiler: csky-linux-gcc (GCC) 12.3.0
reproduce (this is a W=1 build):
mkdir -p ~/bin
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
git checkout v6.4-rc6
b4 shazam https://lore.kernel.org/r/20230613083626.227476-3-frank@oltmanns.dev
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.3.0 ~/bin/make.cross W=1 O=build_dir ARCH=csky olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.3.0 ~/bin/make.cross W=1 O=build_dir ARCH=csky SHELL=/bin/bash
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202306132038.nUB6hmCv-lkp@intel.com/
All errors (new ones prefixed by >>, old ones prefixed by <<):
>> ERROR: modpost: "clk_fractional_divider_general_approximation" [drivers/clk/clk_test.ko] undefined!
Hi Stephen, Thank you for your feedback. On 2023-06-13 at 12:42:05 -0700, Stephen Boyd <sboyd@kernel.org> wrote: > Quoting Frank Oltmanns (2023-06-13 01:36:26) >> In light of the recent discovery that the fractional divisor >> approximation does not utilize the full available range for clocks that >> are flagged CLK_FRAC_DIVIDER_ZERO_BASED, implement tests for the edge >> cases of this clock type. >> >> Signed-off-by: Frank Oltmanns <frank@oltmanns.dev> >> Link: https://lore.kernel.org/lkml/20230529133433.56215-1-frank@oltmanns.dev > > What is the link for? The intention was to show why the tests were added ("In light of the recent discovery..."). I announced this discovery in the mail I referred to. Since that intention didn't come across: Should I drop the link? > >> --- >> drivers/clk/clk_test.c | 69 +++++++++++++++++++++++++++++++++++++++++- > > Please make a new file, drivers/clk/clk-fractional-divider_test.c > instead. > >> 1 file changed, 68 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/clk/clk_test.c b/drivers/clk/clk_test.c >> index f9a5c2964c65..b247ba841cbd 100644 >> --- a/drivers/clk/clk_test.c >> +++ b/drivers/clk/clk_test.c >> @@ -8,6 +8,9 @@ >> /* Needed for clk_hw_get_clk() */ >> #include "clk.h" >> >> +/* Needed for clk_fractional_divider_general_approximation */ >> +#include "clk-fractional-divider.h" >> + >> #include <kunit/test.h> >> >> #define DUMMY_CLOCK_INIT_RATE (42 * 1000 * 1000) >> @@ -2394,6 +2397,69 @@ static struct kunit_suite clk_mux_notifier_test_suite = { >> .test_cases = clk_mux_notifier_test_cases, >> }; >> >> + >> +/* >> + * Test that clk_fractional_divider_general_approximation will work with the >> + * highest available numerator and denominator. >> + */ >> +static void clk_fd_test_round_rate_max_mn(struct kunit *test) >> +{ >> + struct clk_fractional_divider *fd; >> + struct clk_hw *hw; >> + unsigned long rate, parent_rate, m, n; >> + >> + fd = kunit_kzalloc(test, sizeof(*fd), GFP_KERNEL); >> + KUNIT_ASSERT_NOT_NULL(test, fd); >> + >> + fd->mwidth = 3; >> + fd->nwidth = 3; >> + >> + hw = &fd->hw; >> + >> + rate = DUMMY_CLOCK_RATE_1; >> + >> + // Highest denominator, no flags > > Use /* this for comments */ > >> + parent_rate = 10 * DUMMY_CLOCK_RATE_1; > > Just write out the actual frequency. Don't use DUMMY_CLOCK_RATE_1 at all > in the test. Sure, will do. The idea was to highlight that we want to have the parent running at 10 times the speed, while the divider has a maximum value of 7 (or 8 if zero based). > >> + clk_fractional_divider_general_approximation(hw, rate, &parent_rate, &m, &n); >> + KUNIT_EXPECT_EQ(test, m, 1); >> + KUNIT_EXPECT_EQ(test, n, 7); > > This is a different test case. > >> + >> + // Highest numerator, no flags >> + parent_rate = DUMMY_CLOCK_RATE_1 / 10; >> + clk_fractional_divider_general_approximation(hw, rate, &parent_rate, &m, &n); >> + KUNIT_EXPECT_EQ(test, m, 7); > > Is 7 related to mwidth? Maybe this should be clk_div_mask(fd->mwidth) > instead of 7. Yes, 7 is related to mwidth. I thought about this too, but I'm not sure that's the best move here. The function under test uses: max_m = GENMASK(fd->mwidth - 1, 0); max_n = GENMASK(fd->nwidth - 1, 0); I come from a safety-concerned industry and as a general rule we avoid using functions from the code under test in our tests. I'm doing this here as a hobby, but still I find it to be a good rule that I'd like to stick to unless asked otherwise. If I use the same code to generate the expected values, I'm not really testing my change, but only the underlying best_rational_approximation. Instead, how about I add a comment to the test function that more thoroughly explains its intention? Something along those lines: /* * Introduce a parent that runs at 10 times the frequency of the * requested rate. * m and n are 3 bits wide each. * The clock has no flags set, hence the maximum value that fits in * m and n is 7. * Therefore, expect the highest possible divisor. */ static void clk_fd_test_round_rate_max_m(struct kunit *test) /* * Introduce a parent that runs at 1/10th the frequency of the * requested rate. * m and n are 3 bits wide each. * The clock has no flags set, hence the maximum value that fits in * m and n is 7. * Therefore, expect the highest possible multiplier. */ static void clk_fd_test_round_rate_max_n(struct kunit *test) /* * Introduce a parent that runs at 10 times the frequency of the * requested rate. * m and n are 3 bits wide each. * The clock is zero based, hence the maximum value that fits in * m and n is 8. * Therefore, expect the highest possible divisor. */ static void clk_fd_test_round_rate_max_m_zero_based(struct kunit *test) /* * Introduce a parent that runs at 1/10th the frequency of the * requested rate. * m and n are 3 bits wide each. * The clock is zero based, hence the maximum value that fits in * m and n is 8. * Therefore, expect the highest possible multiplier. */ static void clk_fd_test_round_rate_max_n_zero_based(struct kunit *test) Please note that from your original comment, I wasn't sure, if you wanted a one time test or someting that could become part of the clk-frameworks test suite. Therefore, I sent this test case to test the waters and ask for your comments. It's clear to me now that you want it to be permanent, so I'll spend some time on it to make it ready for inclusion. :) Is there anything else you'd like me to cover in the tests for the fix? Thanks, Frank > >> + KUNIT_EXPECT_EQ(test, n, 1); > > This is a different test case. > >> + >> + // Highest denominator, zero based >> + parent_rate = 10 * DUMMY_CLOCK_RATE_1; >> + fd->flags = CLK_FRAC_DIVIDER_ZERO_BASED; >> + clk_fractional_divider_general_approximation(hw, rate, &parent_rate, &m, &n); >> + KUNIT_EXPECT_EQ(test, m, 1); >> + KUNIT_EXPECT_EQ(test, n, 8); > > This is a different test case. > >> + >> + // Highest numerator, zero based >> + parent_rate = DUMMY_CLOCK_RATE_1 / 10; >> + clk_fractional_divider_general_approximation(hw, rate, &parent_rate, &m, &n); >> + KUNIT_EXPECT_EQ(test, m, 8); >> + KUNIT_EXPECT_EQ(test, n, 1); > > This is a different test case. If it has a meaningful name it will be > easier to understand as well.
Hi, On 2023-06-13 at 20:48:21 +0800, kernel test robot <lkp@intel.com> wrote: > Hi Frank, > > kernel test robot noticed the following build errors: > > [auto build test ERROR on v6.4-rc6] > [also build test ERROR on linus/master] > [cannot apply to clk/clk-next next-20230613] > [If your patch is applied to the wrong git tree, kindly drop us a note. > And when submitting patch, we suggest to use '--base' as documented in > https://git-scm.com/docs/git-format-patch#_base_tree_information] > > url: https://github.com/intel-lab-lkp/linux/commits/Frank-Oltmanns/clk-fractional-divider-Improve-approximation-when-zero-based/20230613-163903 > base: v6.4-rc6 > patch link: https://lore.kernel.org/r/20230613083626.227476-3-frank%40oltmanns.dev > patch subject: [PATCH v2 2/2] clk: tests: Add tests for fractional divisor approximation > config: csky-randconfig-r011-20230612 (https://download.01.org/0day-ci/archive/20230613/202306132038.nUB6hmCv-lkp@intel.com/config) > compiler: csky-linux-gcc (GCC) 12.3.0 > reproduce (this is a W=1 build): > mkdir -p ~/bin > wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross > chmod +x ~/bin/make.cross > git checkout v6.4-rc6 > b4 shazam https://lore.kernel.org/r/20230613083626.227476-3-frank@oltmanns.dev > # save the config file > mkdir build_dir && cp config build_dir/.config > COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.3.0 ~/bin/make.cross W=1 O=build_dir ARCH=csky olddefconfig > COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.3.0 ~/bin/make.cross W=1 O=build_dir ARCH=csky SHELL=/bin/bash > > If you fix the issue in a separate patch/commit (i.e. not just a new version of > the same patch/commit), kindly add following tags > | Reported-by: kernel test robot <lkp@intel.com> > | Closes: https://lore.kernel.org/oe-kbuild-all/202306132038.nUB6hmCv-lkp@intel.com/ > > All errors (new ones prefixed by >>, old ones prefixed by <<): > >>> ERROR: modpost: "clk_fractional_divider_general_approximation" [drivers/clk/clk_test.ko] undefined! The issue seems to be that clk_fractional_divider_general_approximation is not exported as a symbol, while the config builds the clk_test as a module: CONFIG_CLK_KUNIT_TEST=m If I'm not mistaken, this means that I can't test clk_fractional_divider_general_approximation directly. Instead I'd have to test it using clk_fractional_divider_ops.round_rate. Can someone more knowlegdable than me please confirm if my understanding is correct? Thanks, Frank
Hi Stephen, On 2023-06-14 at 13:02:24 -0700, Stephen Boyd <sboyd@kernel.org> wrote: > Quoting Frank Oltmanns (2023-06-14 01:19:37) >> Hi, >> >> On 2023-06-13 at 20:48:21 +0800, kernel test robot <lkp@intel.com> wrote: >> > Hi Frank, >> > >> > kernel test robot noticed the following build errors: >> > >> > [auto build test ERROR on v6.4-rc6] >> > [also build test ERROR on linus/master] >> > [cannot apply to clk/clk-next next-20230613] >> > [If your patch is applied to the wrong git tree, kindly drop us a note. >> > And when submitting patch, we suggest to use '--base' as documented in >> > https://git-scm.com/docs/git-format-patch#_base_tree_information] >> > >> > url: https://github.com/intel-lab-lkp/linux/commits/Frank-Oltmanns/clk-fractional-divider-Improve-approximation-when-zero-based/20230613-163903 >> > base: v6.4-rc6 >> > patch link: https://lore.kernel.org/r/20230613083626.227476-3-frank%40oltmanns.dev >> > patch subject: [PATCH v2 2/2] clk: tests: Add tests for fractional divisor approximation >> > config: csky-randconfig-r011-20230612 (https://download.01.org/0day-ci/archive/20230613/202306132038.nUB6hmCv-lkp@intel.com/config) >> > compiler: csky-linux-gcc (GCC) 12.3.0 >> > reproduce (this is a W=1 build): >> > mkdir -p ~/bin >> > wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross >> > chmod +x ~/bin/make.cross >> > git checkout v6.4-rc6 >> > b4 shazam https://lore.kernel.org/r/20230613083626.227476-3-frank@oltmanns.dev >> > # save the config file >> > mkdir build_dir && cp config build_dir/.config >> > COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.3.0 ~/bin/make.cross W=1 O=build_dir ARCH=csky olddefconfig >> > COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.3.0 ~/bin/make.cross W=1 O=build_dir ARCH=csky SHELL=/bin/bash >> > >> > If you fix the issue in a separate patch/commit (i.e. not just a new version of >> > the same patch/commit), kindly add following tags >> > | Reported-by: kernel test robot <lkp@intel.com> >> > | Closes: https://lore.kernel.org/oe-kbuild-all/202306132038.nUB6hmCv-lkp@intel.com/ >> > >> > All errors (new ones prefixed by >>, old ones prefixed by <<): >> > >> >>> ERROR: modpost: "clk_fractional_divider_general_approximation" [drivers/clk/clk_test.ko] undefined! >> >> The issue seems to be that clk_fractional_divider_general_approximation >> is not exported as a symbol, while the config builds the clk_test as a >> module: >> CONFIG_CLK_KUNIT_TEST=m >> >> If I'm not mistaken, this means that I can't test >> clk_fractional_divider_general_approximation directly. Instead I'd have >> to test it using clk_fractional_divider_ops.round_rate. >> >> Can someone more knowlegdable than me please confirm if my understanding >> is correct? > > Export the symbol. Ok. I can do that. Please note that I had already submitted a V3 [1], that went the way of using clk_fractional_divider_ops.round_rate. I apologize for not waiting for your feedback prior to submission. It won't happen again. I liked the approach of calling clk_fd_round_rate directly via the ops, because it might allow me to test the other ops as well using the same blueprint. Of course, I will not add test cases, if you don't want it. (Calling clk_fd_round_rate also had the side effect of teaching me, that fd clocks expect the fraction to be less than or equal to 1.) I don't want to waste your time, but if you could maybe have a chance to look at the approach I took in V3 and tell me if you still want me to export the symbol instead, that would be really helpful. I'll follow your preference. If I don't hear back until the weekend, I will treat your three words above as your preference and prepare a V4 that goes back to calling clk_fractional_divider_general_approximation directly. Thank you, Frank [1]: https://lore.kernel.org/all/20230614185521.477924-3-frank@oltmanns.dev/
Hi Stephen, On 2023-06-16 at 12:33:51 -0700, Stephen Boyd <sboyd@kernel.org> wrote: > Quoting Frank Oltmanns (2023-06-14 22:16:17) >> Hi Stephen, >> >> On 2023-06-14 at 13:02:24 -0700, Stephen Boyd <sboyd@kernel.org> wrote: >> > Quoting Frank Oltmanns (2023-06-14 01:19:37) >> >> Hi, >> >> >> >> On 2023-06-13 at 20:48:21 +0800, kernel test robot <lkp@intel.com> wrote: >> >> Can someone more knowlegdable than me please confirm if my understanding >> >> is correct? >> > >> > Export the symbol. >> >> Ok. I can do that. Please note that I had already submitted a V3 [1], >> that went the way of using clk_fractional_divider_ops.round_rate. I >> apologize for not waiting for your feedback prior to submission. It >> won't happen again. >> >> I liked the approach of calling clk_fd_round_rate directly via the ops, >> because it might allow me to test the other ops as well using the same >> blueprint. Of course, I will not add test cases, if you don't want it. >> (Calling clk_fd_round_rate also had the side effect of teaching me, that >> fd clocks expect the fraction to be less than or equal to 1.) >> >> I don't want to waste your time, but if you could maybe have a chance to >> look at the approach I took in V3 and tell me if you still want me to >> export the symbol instead, that would be really helpful. I'll follow >> your preference. >> >> If I don't hear back until the weekend, I will treat your three words >> above as your preference and prepare a V4 that goes back to calling >> clk_fractional_divider_general_approximation directly. >> > > Just call the API directly. That narrows the test to exactly what we > want to test. If you export the API it will make the rockchip folks > happy too[1]. We of course need to make sure that the registration API > works as well and actually uses the widths that are passed in, but it > doesn't need to fully exercise the approximation algorithm. > > [1] https://lore.kernel.org/r/20230601095512.18029-1-zhangqing@rock-chips.com I've now submitted V5 [1] of this patchset. Unfortunately, V4 [2] had a compiler warning on clang that slipped through the cracks. I'm sorry for the noise. In my opinion V5 is ready for review and hopefully addresses all your previous concerns. Thank you for your patience. Best regards, Frank [1] https://lore.kernel.org/all/20230617131041.18313-1-frank@oltmanns.dev/ [2] https://lore.kernel.org/all/20230617102919.27564-1-frank@oltmanns.dev/
diff --git a/drivers/clk/clk_test.c b/drivers/clk/clk_test.c index f9a5c2964c65..b247ba841cbd 100644 --- a/drivers/clk/clk_test.c +++ b/drivers/clk/clk_test.c @@ -8,6 +8,9 @@ /* Needed for clk_hw_get_clk() */ #include "clk.h" +/* Needed for clk_fractional_divider_general_approximation */ +#include "clk-fractional-divider.h" + #include <kunit/test.h> #define DUMMY_CLOCK_INIT_RATE (42 * 1000 * 1000) @@ -2394,6 +2397,69 @@ static struct kunit_suite clk_mux_notifier_test_suite = { .test_cases = clk_mux_notifier_test_cases, }; + +/* + * Test that clk_fractional_divider_general_approximation will work with the + * highest available numerator and denominator. + */ +static void clk_fd_test_round_rate_max_mn(struct kunit *test) +{ + struct clk_fractional_divider *fd; + struct clk_hw *hw; + unsigned long rate, parent_rate, m, n; + + fd = kunit_kzalloc(test, sizeof(*fd), GFP_KERNEL); + KUNIT_ASSERT_NOT_NULL(test, fd); + + fd->mwidth = 3; + fd->nwidth = 3; + + hw = &fd->hw; + + rate = DUMMY_CLOCK_RATE_1; + + // Highest denominator, no flags + parent_rate = 10 * DUMMY_CLOCK_RATE_1; + clk_fractional_divider_general_approximation(hw, rate, &parent_rate, &m, &n); + KUNIT_EXPECT_EQ(test, m, 1); + KUNIT_EXPECT_EQ(test, n, 7); + + // Highest numerator, no flags + parent_rate = DUMMY_CLOCK_RATE_1 / 10; + clk_fractional_divider_general_approximation(hw, rate, &parent_rate, &m, &n); + KUNIT_EXPECT_EQ(test, m, 7); + KUNIT_EXPECT_EQ(test, n, 1); + + // Highest denominator, zero based + parent_rate = 10 * DUMMY_CLOCK_RATE_1; + fd->flags = CLK_FRAC_DIVIDER_ZERO_BASED; + clk_fractional_divider_general_approximation(hw, rate, &parent_rate, &m, &n); + KUNIT_EXPECT_EQ(test, m, 1); + KUNIT_EXPECT_EQ(test, n, 8); + + // Highest numerator, zero based + parent_rate = DUMMY_CLOCK_RATE_1 / 10; + clk_fractional_divider_general_approximation(hw, rate, &parent_rate, &m, &n); + KUNIT_EXPECT_EQ(test, m, 8); + KUNIT_EXPECT_EQ(test, n, 1); +} + +static struct kunit_case clk_fd_test_cases[] = { + KUNIT_CASE(clk_fd_test_round_rate_max_mn), + {} +}; + +/* + * Test suite for a fractional divider clock. + * + * These tests exercise the fractional divider API: clk_recalc_rate, + * clk_set_rate(), clk_round_rate(). + */ +static struct kunit_suite clk_fd_test_suite = { + .name = "clk-fd-test", + .test_cases = clk_fd_test_cases, +}; + kunit_test_suites( &clk_leaf_mux_set_rate_parent_test_suite, &clk_test_suite, @@ -2406,6 +2472,7 @@ kunit_test_suites( &clk_range_maximize_test_suite, &clk_range_minimize_test_suite, &clk_single_parent_mux_test_suite, - &clk_uncached_test_suite + &clk_uncached_test_suite, + &clk_fd_test_suite ); MODULE_LICENSE("GPL v2");
In light of the recent discovery that the fractional divisor approximation does not utilize the full available range for clocks that are flagged CLK_FRAC_DIVIDER_ZERO_BASED, implement tests for the edge cases of this clock type. Signed-off-by: Frank Oltmanns <frank@oltmanns.dev> Link: https://lore.kernel.org/lkml/20230529133433.56215-1-frank@oltmanns.dev --- drivers/clk/clk_test.c | 69 +++++++++++++++++++++++++++++++++++++++++- 1 file changed, 68 insertions(+), 1 deletion(-)