On 08/31/2018 03:29 AM, Stephen Boyd wrote:

Quoting Peng Fan (2018-08-12 18:15:41)

quoted

Hi Anson,

quoted

quoted

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-----Original Message-----
From: Anson Huang
Sent: 2018?8?8? 12:39
To: shawnguo at kernel.org; s.hauer at pengutronix.de;
kernel at pengutronix.de; Fabio Estevam [off-list ref];
mturquette at baylibre.com; sboyd at kernel.org;
linux-arm-kernel at lists.infradead.org;
linux-clk at vger.kernel.org; linux-kernel at vger.kernel.org
Cc: dl-linux-imx <redacted>
Subject: [PATCH 2/2] clk: imx: imx7d: remove clks_init_on array

Clock framework will enable those clocks registered with
CLK_IS_CRITICAL flag, so no need to have clks_init_on array during
clock

initialization now.

Will it be more flexible to parse dts saying "critical-clocks = <xxx>"
or "init-on-arrary=<xxx>"
and enable those clocks?

Parsing the clocks arrays from dtb is another way of enabling critical clocks, but
for current i.MX6/7 platforms, we implement it in same way as most of other
SoCs, currently I did NOT see any necessity of putting them in dtb, just adding
flag during clock registering is more simple, if there is any special requirement
for different clocks set to be enabled, then we can add support to enable the
method of parsing critical-clocks from dtb. Just my two cents.

Thinking about OP-TEE want to use one device, but it's clocks are registered
by Linux, because there is no module in Linux side use it, it will shutdown the clock,
which cause OP-TEE could not access the device.

Then people have to modify clk code to add CLK_IS_CRITICAL flag to make sure
the clocks are not shutdown by Linux.

However adding a new property in clk node and let driver code parse the dts,
there is no need to modify clk driver code when OP-TEE needs another device clock.

If OP-TEE needs linux to keep things on then why can't the OP-TEE driver
in Linux probe, acquire clocks, and keep the clks enabled forever?

Sounds reasonable, but how could this be done without introducing
platform-specific stuff in the OP-TEE driver?

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