[v4,17/68] clk: lochnagar: Add a determine_rate hook

Commit Message

Maxime Ripard May 5, 2023, 11:25 a.m. UTC

The lochnagar clocks implement a mux with a set_parent hook, but
doesn't provide a determine_rate implementation.

This is a bit odd, since set_parent() is there to, as its name implies,
change the parent of a clock. However, the most likely candidates to
trigger that parent change are either the assigned-clock-parents device
tree property or a call to clk_set_rate(), with determine_rate()
figuring out which parent is the best suited for a given rate.

The other trigger would be a call to clk_set_parent(), but it's far less
used, and it doesn't look like there's any obvious user for that clock.

Since there's no upstream device tree using that driver, it's a bit hard
to tell if it uses the assigned-clock properties. The binding and its
example uses them though, so it's likely that the author intent was to
force the parent through the device tree and prevent any reparenting but
through an explicit call to clk_set_parent().

This case is equivalent to setting the determine_rate implementation to
clk_hw_determine_rate_no_reparent(). Indeed, if no determine_rate
implementation is provided, clk_round_rate() (through
clk_core_round_rate_nolock()) will call itself on the parent if
CLK_SET_RATE_PARENT is set, and will not change the clock rate
otherwise.

Cc: Charles Keepax <[e-mail]>
Cc: Richard Fitzgerald <[e-mail]>
Cc: [e-mail]
Tested-by: Charles Keepax <[e-mail]>
Signed-off-by: Maxime Ripard <[e-mail]>
---
 drivers/clk/clk-lochnagar.c | 1 +
 1 file changed, 1 insertion(+)

Comments

kernel test robot May 5, 2023, 5:46 p.m. UTC | #1

Hi Maxime,

kernel test robot noticed the following build errors:

[auto build test ERROR on 145e5cddfe8b4bf607510b2dcf630d95f4db420f]

url:    https://github.com/intel-lab-lkp/linux/commits/Maxime-Ripard/clk-Export-clk_hw_forward_rate_request/20230505-193724
base:   145e5cddfe8b4bf607510b2dcf630d95f4db420f
patch link:    https://lore.kernel.org/r/20221018-clk-range-checks-fixes-v4-17-971d5077e7d2%40cerno.tech
patch subject: [PATCH v4 17/68] clk: lochnagar: Add a determine_rate hook
config: i386-randconfig-a012-20230501 (https://download.01.org/0day-ci/archive/20230506/[e-mail]/config)
compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project f28c006a5895fc0e329fe15fead81e37457cb1d1)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/273bc4689da3909aebca0a3479e18194a748ee92
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Maxime-Ripard/clk-Export-clk_hw_forward_rate_request/20230505-193724
        git checkout 273bc4689da3909aebca0a3479e18194a748ee92
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=i386 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=i386 SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <[e-mail]>
| Link: https://lore.kernel.org/oe-kbuild-all/[e-mail]/

All errors (new ones prefixed by >>, old ones prefixed by <<):

>> ERROR: modpost: "clk_hw_determine_rate_no_reparent" [drivers/clk/clk-lochnagar.ko] undefined!

kernel test robot May 5, 2023, 6:47 p.m. UTC | #2

Hi Maxime,

kernel test robot noticed the following build errors:

[auto build test ERROR on 145e5cddfe8b4bf607510b2dcf630d95f4db420f]

url:    https://github.com/intel-lab-lkp/linux/commits/Maxime-Ripard/clk-Export-clk_hw_forward_rate_request/20230505-193724
base:   145e5cddfe8b4bf607510b2dcf630d95f4db420f
patch link:    https://lore.kernel.org/r/20221018-clk-range-checks-fixes-v4-17-971d5077e7d2%40cerno.tech
patch subject: [PATCH v4 17/68] clk: lochnagar: Add a determine_rate hook
config: arm-allmodconfig (https://download.01.org/0day-ci/archive/20230506/[e-mail]/config)
compiler: arm-linux-gnueabi-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/273bc4689da3909aebca0a3479e18194a748ee92
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Maxime-Ripard/clk-Export-clk_hw_forward_rate_request/20230505-193724
        git checkout 273bc4689da3909aebca0a3479e18194a748ee92
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=arm olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=arm SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <[e-mail]>
| Link: https://lore.kernel.org/oe-kbuild-all/[e-mail]/

All errors (new ones prefixed by >>, old ones prefixed by <<):

ERROR: modpost: "clk_hw_determine_rate_no_reparent" [drivers/clk/clk_test.ko] undefined!
ERROR: modpost: "clk_hw_determine_rate_no_reparent" [drivers/clk/clk-cdce706.ko] undefined!
>> ERROR: modpost: "clk_hw_determine_rate_no_reparent" [drivers/clk/clk-lochnagar.ko] undefined!

Patch

diff --git a/drivers/clk/clk-lochnagar.c b/drivers/clk/clk-lochnagar.c
index 80944bf482e9..db468a62c8d7 100644
--- a/drivers/clk/clk-lochnagar.c
+++ b/drivers/clk/clk-lochnagar.c
@@ -209,6 +209,7 @@  static u8 lochnagar_clk_get_parent(struct clk_hw *hw)
 static const struct clk_ops lochnagar_clk_ops = {
 	.prepare = lochnagar_clk_prepare,
 	.unprepare = lochnagar_clk_unprepare,
+	.determine_rate = clk_hw_determine_rate_no_reparent,
 	.set_parent = lochnagar_clk_set_parent,
 	.get_parent = lochnagar_clk_get_parent,
 };