From: Lee Jones <lee.jones@linaro.org>
To: Peter Griffin <peter.griffin@linaro.org>
Cc: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, kernel@stlinux.com,
patrice.chotard@st.com, devicetree@vger.kernel.org
Subject: Re: [PATCH] ARM: sti: stih410-clocks: Add PROC_STFE as a critical clock
Date: Mon, 24 Oct 2016 09:53:04 +0100 [thread overview]
Message-ID: <20161024085304.GE14477@dell> (raw)
In-Reply-To: <1476804957-24000-1-git-send-email-peter.griffin@linaro.org>
On Tue, 18 Oct 2016, Peter Griffin wrote:
> Once the ST frontend demux HW IP has been enabled, the clock can't
> be disabled otherwise the system will hang and the board will
> be unserviceable.
>
> To allow balanced clock enable/disable calls in the driver we use
> the critical clock infrastructure to take an extra reference on the
> clock so the clock will never actually be disabled.
This is an abuse of the critical-clocks framework, and is exactly the
type of hack I promised the clk guys I'd try to prevent. If this, or
any other IP has some quirks (i.e. once enabled, if this clock is
subsequently disabled it will have a catastrophic effect on the
platform), then they should be worked around in the driver.
The correct thing to do here is craft a clk-keep-on flag and ensure it
is set to true for the effected platform(s)' platform data.
> Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
> ---
> arch/arm/boot/dts/stih410-clock.dtsi | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/boot/dts/stih410-clock.dtsi b/arch/arm/boot/dts/stih410-clock.dtsi
> index 8598eff..07c8ef9 100644
> --- a/arch/arm/boot/dts/stih410-clock.dtsi
> +++ b/arch/arm/boot/dts/stih410-clock.dtsi
> @@ -208,7 +208,8 @@
> "clk-clust-hades",
> "clk-hwpe-hades",
> "clk-fc-hades";
> - clock-critical = <CLK_ICN_CPU>,
> + clock-critical = <CLK_PROC_STFE>,
> + <CLK_ICN_CPU>,
> <CLK_TX_ICN_DMU>,
> <CLK_EXT2F_A9>,
> <CLK_ICN_LMI>,
--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog
next prev parent reply other threads:[~2016-10-24 8:50 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-18 15:35 [PATCH] ARM: sti: stih410-clocks: Add PROC_STFE as a critical clock Peter Griffin
2016-10-20 13:50 ` Patrice Chotard
2016-10-24 8:53 ` Lee Jones [this message]
2016-10-24 13:44 ` Peter Griffin
2016-10-25 7:42 ` Lee Jones
2016-10-25 9:39 ` Peter Griffin
2016-10-25 10:01 ` Lee Jones
2016-10-25 13:49 ` Peter Griffin
2016-10-26 8:51 ` Lee Jones
2016-10-26 8:56 ` Peter Griffin
2016-10-26 13:00 ` Lee Jones
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