| Message ID | 20220503130448.520470-2-robert.foss@linaro.org (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | [v2,1/8] clk: qcom: rcg2: Cache rate changes for parked RCGs | expand |
On Tue 03 May 08:04 CDT 2022, Robert Foss wrote: > From: Bjorn Andersson <bjorn.andersson@linaro.org> > > Some clock implementations doesn't provide means of implementing > is_enabled(), but still requires to be explicitly disabled when found > unused as part of clk_disable_unused(). > > One such set of clocks are Qualcomm's display RCGs. These can be enabled > and disabled automatically by the hardware, so it's not possible to > reliably query their configuration. Further more, these clocks need to > be disabled when unused, to allow them to be "parked" onto a safe > parent. Failure to disable the RCG results in the hardware locking up as > clk_disable_unused() traverses up the tree and turns off its source > clocks. > > Add a new flag, CLK_ASSUME_ENABLED_BOOT, which clock drivers can use to > signal that these clocks should be disabled even if they don't implement > the is_enabled() ops. > > Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org> > --- > I discussed this with Stephen a while ago and we agreed that in a sufficiently complex system with kernel modules booting without clk_ignore_unused simply isn't supported. We will have to design something better. So please drop this patch from the series. Regards, Bjorn > Changes since v1 > - Removed Vinods r-b > > > drivers/clk/clk.c | 2 +- > include/linux/clk-provider.h | 2 ++ > 2 files changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c > index ed119182aa1b..9789ec137219 100644 > --- a/drivers/clk/clk.c > +++ b/drivers/clk/clk.c > @@ -1284,7 +1284,7 @@ static void __init clk_disable_unused_subtree(struct clk_core *core) > * sequence. call .disable_unused if available, otherwise fall > * back to .disable > */ > - if (clk_core_is_enabled(core)) { > + if (clk_core_is_enabled(core) || core->flags & CLK_ASSUME_ENABLED_WHEN_UNUSED) { > trace_clk_disable(core); > if (core->ops->disable_unused) > core->ops->disable_unused(core->hw); > diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h > index c10dc4c659e2..9038022ffebd 100644 > --- a/include/linux/clk-provider.h > +++ b/include/linux/clk-provider.h > @@ -32,6 +32,8 @@ > #define CLK_OPS_PARENT_ENABLE BIT(12) > /* duty cycle call may be forwarded to the parent clock */ > #define CLK_DUTY_CYCLE_PARENT BIT(13) > +/* assume clock is enabled if found unused in late init */ > +#define CLK_ASSUME_ENABLED_WHEN_UNUSED BIT(14) > > struct clk; > struct clk_hw; > -- > 2.34.1 >
On Tue, 3 May 2022 at 17:02, Bjorn Andersson <bjorn.andersson@linaro.org> wrote: > > On Tue 03 May 08:04 CDT 2022, Robert Foss wrote: > > > From: Bjorn Andersson <bjorn.andersson@linaro.org> > > > > Some clock implementations doesn't provide means of implementing > > is_enabled(), but still requires to be explicitly disabled when found > > unused as part of clk_disable_unused(). > > > > One such set of clocks are Qualcomm's display RCGs. These can be enabled > > and disabled automatically by the hardware, so it's not possible to > > reliably query their configuration. Further more, these clocks need to > > be disabled when unused, to allow them to be "parked" onto a safe > > parent. Failure to disable the RCG results in the hardware locking up as > > clk_disable_unused() traverses up the tree and turns off its source > > clocks. > > > > Add a new flag, CLK_ASSUME_ENABLED_BOOT, which clock drivers can use to > > signal that these clocks should be disabled even if they don't implement > > the is_enabled() ops. > > > > Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org> > > --- > > > > I discussed this with Stephen a while ago and we agreed that in a > sufficiently complex system with kernel modules booting without > clk_ignore_unused simply isn't supported. > > We will have to design something better. So please drop this patch from > the series. Ack
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index ed119182aa1b..9789ec137219 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -1284,7 +1284,7 @@ static void __init clk_disable_unused_subtree(struct clk_core *core) * sequence. call .disable_unused if available, otherwise fall * back to .disable */ - if (clk_core_is_enabled(core)) { + if (clk_core_is_enabled(core) || core->flags & CLK_ASSUME_ENABLED_WHEN_UNUSED) { trace_clk_disable(core); if (core->ops->disable_unused) core->ops->disable_unused(core->hw); diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h index c10dc4c659e2..9038022ffebd 100644 --- a/include/linux/clk-provider.h +++ b/include/linux/clk-provider.h @@ -32,6 +32,8 @@ #define CLK_OPS_PARENT_ENABLE BIT(12) /* duty cycle call may be forwarded to the parent clock */ #define CLK_DUTY_CYCLE_PARENT BIT(13) +/* assume clock is enabled if found unused in late init */ +#define CLK_ASSUME_ENABLED_WHEN_UNUSED BIT(14) struct clk; struct clk_hw;