| Message ID | 1466741572-58802-1-git-send-email-neidhard.kim@lge.com (mailing list archive) |
|---|---|
| State | Rejected, archived |
| Headers | show |
On Fri, Jun 24, 2016 at 01:12:52PM +0900, Jongsung Kim wrote: > There is no way to set additional flags for a DT-initialized fixed- > factor-clock, and it can be problematic i.e., when the clock rate > needs to be changed. [1][2] > > This patch introduces an optional dt-binding named "clock-flags" to > be used for passing any needed flags from dts. I don't think we want this in DT. If we did, the flags would need some documentation about what the flags mean. Rob -- To unsubscribe from this list: send the line "unsubscribe linux-clk" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Quoting Rob Herring (2016-06-28 13:55:18) > On Fri, Jun 24, 2016 at 01:12:52PM +0900, Jongsung Kim wrote: > > There is no way to set additional flags for a DT-initialized fixed- > > factor-clock, and it can be problematic i.e., when the clock rate > > needs to be changed. [1][2] > > > > This patch introduces an optional dt-binding named "clock-flags" to > > be used for passing any needed flags from dts. > > I don't think we want this in DT. If we did, the flags would need some > documentation about what the flags mean. Flags are specific to Linux implementation, so I agree with Rob. Better to create a compatible string for your hardware that bakes in the flags. Regards, Mike > > Rob -- To unsubscribe from this list: send the line "unsubscribe linux-clk" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 2016년 06월 29일 05:55, Rob Herring wrote: > On Fri, Jun 24, 2016 at 01:12:52PM +0900, Jongsung Kim wrote: >> There is no way to set additional flags for a DT-initialized fixed- >> factor-clock, and it can be problematic i.e., when the clock rate >> needs to be changed. [1][2] >> >> This patch introduces an optional dt-binding named "clock-flags" to >> be used for passing any needed flags from dts. > I don't think we want this in DT. If we did, the flags would need some > documentation about what the flags mean. Thanks for your comment. It looks not that big deal to provide a little documentation..? Some of the flags looks safe to be removed. Thinking of only fixed-factor-clock, most of them can be removed. -- To unsubscribe from this list: send the line "unsubscribe linux-clk" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 2016년 06월 29일 06:18, Michael Turquette wrote: > Quoting Rob Herring (2016-06-28 13:55:18) >> On Fri, Jun 24, 2016 at 01:12:52PM +0900, Jongsung Kim wrote: >>> There is no way to set additional flags for a DT-initialized fixed- >>> factor-clock, and it can be problematic i.e., when the clock rate >>> needs to be changed. [1][2] >>> >>> This patch introduces an optional dt-binding named "clock-flags" to >>> be used for passing any needed flags from dts. >> I don't think we want this in DT. If we did, the flags would need some >> documentation about what the flags mean. > Flags are specific to Linux implementation, so I agree with Rob. Better > to create a compatible string for your hardware that bakes in the flags. Thank you for your comment, Mike. This conversation starts from lacking method to set CLK_SET_RATE_PARENT from DT. I understand compatible string can be a solution. But.. if someone starts talking about lacking method to set another flag, i.e., CLK_SET_PARENT_GATE, then we'll need another compatible string list. How do you think about defining possible required subset of the flags and using some more neutral flag-names acceptable in DT? -- To unsubscribe from this list: send the line "unsubscribe linux-clk" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 06/29, Jongsung Kim wrote: > On 2016년 06월 29일 06:18, Michael Turquette wrote: > > Quoting Rob Herring (2016-06-28 13:55:18) > >> On Fri, Jun 24, 2016 at 01:12:52PM +0900, Jongsung Kim wrote: > >>> There is no way to set additional flags for a DT-initialized fixed- > >>> factor-clock, and it can be problematic i.e., when the clock rate > >>> needs to be changed. [1][2] > >>> > >>> This patch introduces an optional dt-binding named "clock-flags" to > >>> be used for passing any needed flags from dts. > >> I don't think we want this in DT. If we did, the flags would need some > >> documentation about what the flags mean. > > Flags are specific to Linux implementation, so I agree with Rob. Better > > to create a compatible string for your hardware that bakes in the flags. > > Thank you for your comment, Mike. This conversation starts from lacking method to set CLK_SET_RATE_PARENT from DT. I understand compatible string can be a solution. But.. if someone starts talking about lacking method to set another flag, i.e., CLK_SET_PARENT_GATE, then we'll need another compatible string list. > How do you think about defining possible required subset of the flags and using some more neutral flag-names acceptable in DT? Do you actually have an IC on the board that is doing some fixed factor calculation? Or is this a clk driver design where we are listing out each piece of an SoC's clk controller in DT?
On 2016년 07월 02일 09:20, Stephen Boyd wrote: > On 06/29, Jongsung Kim wrote: >> On 2016년 06월 29일 06:18, Michael Turquette wrote: >>> Quoting Rob Herring (2016-06-28 13:55:18) >>>> On Fri, Jun 24, 2016 at 01:12:52PM +0900, Jongsung Kim wrote: >>>>> There is no way to set additional flags for a DT-initialized fixed- >>>>> factor-clock, and it can be problematic i.e., when the clock rate >>>>> needs to be changed. [1][2] >>>>> >>>>> This patch introduces an optional dt-binding named "clock-flags" to >>>>> be used for passing any needed flags from dts. >>>> I don't think we want this in DT. If we did, the flags would need some >>>> documentation about what the flags mean. >>> Flags are specific to Linux implementation, so I agree with Rob. Better >>> to create a compatible string for your hardware that bakes in the flags. >> Thank you for your comment, Mike. This conversation starts from lacking method to set CLK_SET_RATE_PARENT from DT. I understand compatible string can be a solution. But.. if someone starts talking about lacking method to set another flag, i.e., CLK_SET_PARENT_GATE, then we'll need another compatible string list. >> How do you think about defining possible required subset of the flags and using some more neutral flag-names acceptable in DT? > Do you actually have an IC on the board that is doing some fixed > factor calculation? Or is this a clk driver design where we are > listing out each piece of an SoC's clk controller in DT? > The SoC has several PLLs of identical design, and one of them is divided to half and used for CPUs. The fixed-factor-clock represents the divider. -- To unsubscribe from this list: send the line "unsubscribe linux-clk" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 07/04, Jongsung Kim wrote: > On 2016년 07월 02일 09:20, Stephen Boyd wrote: > > Do you actually have an IC on the board that is doing some fixed > > factor calculation? Or is this a clk driver design where we are > > listing out each piece of an SoC's clk controller in DT? > > > The SoC has several PLLs of identical design, and one of them is divided > to half and used for CPUs. The fixed-factor-clock represents the divider. > Ok, so it sounds like we can have the driver that registers the CPU PLL also register the fixed factor clk? I fail to see why we need this from DT in that case.
diff --git a/Documentation/devicetree/bindings/clock/fixed-factor-clock.txt b/Documentation/devicetree/bindings/clock/fixed-factor-clock.txt index 1bae8527..3e1b79e 100644 --- a/Documentation/devicetree/bindings/clock/fixed-factor-clock.txt +++ b/Documentation/devicetree/bindings/clock/fixed-factor-clock.txt @@ -13,12 +13,16 @@ Required properties: Optional properties: - clock-output-names : From common clock binding. +- clock-flags : Additional flags to be used. Example: + #include <dt-bindings/clk/clk.h> + clock { compatible = "fixed-factor-clock"; clocks = <&parentclk>; #clock-cells = <0>; clock-div = <2>; clock-mult = <1>; + clock-flags = <CLK_SET_RATE_PARENT>; }; diff --git a/drivers/clk/clk-fixed-factor.c b/drivers/clk/clk-fixed-factor.c index 75cd6c7..e626cad 100644 --- a/drivers/clk/clk-fixed-factor.c +++ b/drivers/clk/clk-fixed-factor.c @@ -150,6 +150,7 @@ void __init of_fixed_factor_clk_setup(struct device_node *node) struct clk *clk; const char *clk_name = node->name; const char *parent_name; + u32 flags = 0; u32 div, mult; if (of_property_read_u32(node, "clock-div", &div)) { @@ -166,8 +167,9 @@ void __init of_fixed_factor_clk_setup(struct device_node *node) of_property_read_string(node, "clock-output-names", &clk_name); parent_name = of_clk_get_parent_name(node, 0); + of_property_read_u32(node, "clock-flags", &flags); - clk = clk_register_fixed_factor(NULL, clk_name, parent_name, 0, + clk = clk_register_fixed_factor(NULL, clk_name, parent_name, flags, mult, div); if (!IS_ERR(clk)) of_clk_add_provider(node, of_clk_src_simple_get, clk); diff --git a/include/dt-bindings/clk/clk.h b/include/dt-bindings/clk/clk.h new file mode 100644 index 0000000..1834933 --- /dev/null +++ b/include/dt-bindings/clk/clk.h @@ -0,0 +1,22 @@ +/* + * See include/linux/clk-provider.h for more information. + */ + +#ifndef __DT_BINDINGS_CLK_CLK_H +#define __DT_BINDINGS_CLK_CLK_H + +#define BIT(nr) (1UL << (nr)) + +#define CLK_SET_RATE_GATE BIT(0) +#define CLK_SET_PARENT_GATE BIT(1) +#define CLK_SET_RATE_PARENT BIT(2) +#define CLK_IGNORE_UNUSED BIT(3) +#define CLK_IS_BASIC BIT(5) +#define CLK_GET_RATE_NOCACHE BIT(6) +#define CLK_SET_RATE_NO_REPARENT BIT(7) +#define CLK_GET_ACCURACY_NOCACHE BIT(8) +#define CLK_RECALC_NEW_RATES BIT(9) +#define CLK_SET_RATE_UNGATE BIT(10) +#define CLK_IS_CRITICAL BIT(11) + +#endif
There is no way to set additional flags for a DT-initialized fixed- factor-clock, and it can be problematic i.e., when the clock rate needs to be changed. [1][2] This patch introduces an optional dt-binding named "clock-flags" to be used for passing any needed flags from dts. [1] http://www.spinics.net/lists/linux-clk/msg09040.html [2] https://lkml.org/lkml/2016/6/20/1025 Changes since v1: - fix possible build failure when using gcc-5 or gcc-6 Signed-off-by: Jongsung Kim <neidhard.kim@lge.com> Cc: Maxime Ripard <maxime.ripard@free-electrons.com> Cc: Mike Turquette <mturquette@baylibre.com> Cc: Stephen Boyd <sboyd@codeaurora.org> --- .../bindings/clock/fixed-factor-clock.txt | 4 ++++ drivers/clk/clk-fixed-factor.c | 4 +++- include/dt-bindings/clk/clk.h | 22 ++++++++++++++++++++++ 3 files changed, 29 insertions(+), 1 deletion(-) create mode 100644 include/dt-bindings/clk/clk.h