[RESEND PATCH 0/8] clk: core: support clocks which requires parents on

Dong Aisheng dongas86 at gmail.com
Thu Jun 2 08:20:59 PDT 2016

On Wed, Apr 20, 2016 at 05:34:32PM +0800, Dong Aisheng wrote:
> This is a RESEND patch series.
> The original one can be found at here:
> http://www.spinics.net/lists/arm-kernel/msg435136.html
> It has no functional changes but improve the commit message and
> comments a bit.
> This patch series adds support in clock framework for clocks which all the
> operations like gate/ungate, set_rate, set_parent must require its parent
> clock on.
> This special HW requirement can be found on Freescale i.MX7D platform.
> Besides i.MX7D, it seems lpc18xx clock has a similar requirement.
> (see: http://www.spinics.net/lists/arm-kernel/msg439307.html)
> And there may be other SoCs in the same situation.
> Current clock core can not support such type of clock well.
> This patch introduce a new flag CLK_SET_PARENT_ON to handle this special
> case in clock core that enable its parent clock firstly for each operation
> and disable it later after operation complete.
> There're two special cases for handling this issue:
> One is fixing the possible disabling clocks while its parent is already off
> during kernel booting phase in clk_disable_unused_subtree()
> Since this state misalign only happens during booting time,
> so we simply enable the parent clocks before disable it if flag is set.
> For normal clk_disable after kernel booting, there's no such issue
> since the clock tree is already created which makes sure no such issue exist.
> Another special case is for set_parent() operation.
> It requires both parent, old one and new one, to be enabled at the same
> time during the operation.
> Patch 1~4 does this work.
> After clk core supports mx7d type clocks, we don't have to enable all clock
> by default anymore, then we remove the enable of all clocks code and instead
> only enable set of minimum required clocks.
> Patch 5~8 does this work.
> The whole patch series is based on for-next branch of clock tree:
> git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux.git

Hi Stephen,

Could you give some comments about this patch series?

Dong Aisheng

> Dong Aisheng (8):
>   clk: introduce clk_core_enable_lock and clk_core_disable_lock
>     functions
>   clk: move clk_disable_unused after clk_core_disable_unprepare function
>   clk: core: support clocks which requires parents on (part 1)
>   clk: core: support clocks which requires parents on (part 2)
>   clk: imx: re-order and concentrate the same type of clk api
>   clk: imx: add clk api for supporting clk_OPS_PARENT_ON clocks
>   clk: imx7d: using api with flag CLK_OPS_PARENT_ON
>   clk: imx7d: only enable minimum required clocks
>  drivers/clk/clk.c            | 329 +++++++++++--------
>  drivers/clk/imx/clk-imx7d.c  | 732 ++++++++++++++++++++++---------------------
>  drivers/clk/imx/clk.h        |  90 ++++--
>  include/linux/clk-provider.h |   2 +
>  4 files changed, 623 insertions(+), 530 deletions(-)
> -- 
> 1.9.1
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