On 07.08.2014 09:59, Boris BREZILLON wrote:
On Thu, 7 Aug 2014 09:52:31 +0200
Boris BREZILLON <boris.brezil...@free-electrons.com> wrote:
On Wed, 6 Aug 2014 15:11:42 +0200
Ronald Wahl <ronald.w...@raritan.com> wrote:
Commit 7628083227b6bc4a7e33d7c381d7a4e558424b6b added clock preparation in
interrupt context. This is not allowed as it might sleep. Move clock
preparation into process context (at91udc_probe).
---
drivers/usb/gadget/udc/at91_udc.c | 39 ++++++++++++++++++++++++++++++---------
1 file changed, 30 insertions(+), 9 deletions(-)
diff --git a/drivers/usb/gadget/udc/at91_udc.c
b/drivers/usb/gadget/udc/at91_udc.c
index cfd18bc..0b347a0 100644
--- a/drivers/usb/gadget/udc/at91_udc.c
+++ b/drivers/usb/gadget/udc/at91_udc.c
@@ -872,10 +872,10 @@ static void clk_on(struct at91_udc *udc)
if (IS_ENABLED(CONFIG_COMMON_CLK)) {
clk_set_rate(udc->uclk, 48000000);
- clk_prepare_enable(udc->uclk);
+ clk_enable(udc->uclk);
}
- clk_prepare_enable(udc->iclk);
- clk_prepare_enable(udc->fclk);
+ clk_enable(udc->iclk);
+ clk_enable(udc->fclk);
}
static void clk_off(struct at91_udc *udc)
@@ -884,10 +884,10 @@ static void clk_off(struct at91_udc *udc)
return;
udc->clocked = 0;
udc->gadget.speed = USB_SPEED_UNKNOWN;
- clk_disable_unprepare(udc->fclk);
- clk_disable_unprepare(udc->iclk);
+ clk_disable(udc->fclk);
+ clk_disable(udc->iclk);
if (IS_ENABLED(CONFIG_COMMON_CLK))
- clk_disable_unprepare(udc->uclk);
+ clk_disable(udc->uclk);
}
As you stated prepare and unprepare should never be called in interrupt
context.
My concern here is that PLLB (which is often used as USB clock
parent) will never be gated/disabled (because all this work is
done in its unprepare method), and thus your power consumption will be
higher (when entering suspend mode) than if you'd done a
disable_unprepare call.
How about leaving the clk_on/off unchanged and use a threaded irq
instead of a normal irq ?
Even with threaded interrupts things are still called while interrupts
are disabled by one or more layers of spin_lock_irqsave. There are also
different code paths from where clk_on() is called. So getting this
right while saving power is probably not trivial and beyond my
knowledge/experience with the udc code. It would be nice if someone with
a deeper knowledge of the atmel udc code can get this right. My primary
intention was to get the code working again.
thx & greets,
ron
--
Ronald Wahl - ronald.w...@raritan.com - Phone +49 375271349-0 Fax -99
Raritan Deutschland GmbH, Kornmarkt 7, 08056 Zwickau, Germany
USt-IdNr. DE813094160, Steuer-Nr. 227/117/01749
Amtsgericht Chemnitz HRB 23605
Geschäftsführung: Stuart Hopper, Ralf Ploenes
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