Re: [PATCH 3.16.y-ckt 040/216] usb: gadget: at91_udc: move prepare clk into process context

Luis Henriques
2015-01-14T13:53:39Z

On Wed, Jan 14, 2015 at 01:37:38PM +0000, Ben Hutchings wrote:
> On Mon, 2015-01-12 at 18:02 +0000, Luis Henriques wrote:
> > 3.16.7-ckt4 -stable review patch. If anyone has any objections, please let me know.
> >
> > ------------------
> >
> > From: Ronald Wahl <ronald.wahl@raritan.com>
> >
> > commit b2ba27a5c56ff7204d8a8684893d64d4afe2cee5 upstream.
> >
> > Commit 7628083227b6bc4a7e33d7c381d7a4e558424b6b (usb: gadget: at91_udc:
> > prepare clk before calling enable) added clock preparation in interrupt
> > context. This is not allowed as it might sleep. Also setting the clock
> > rate is unsafe to call from there for the same reason. Move clock
> > preparation and setting clock rate into process context (at91udc_probe).
> >
> > Signed-off-by: Ronald Wahl <ronald.wahl@raritan.com>
> > Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
> > Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>
> > Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
> > Cc: Felipe Balbi <balbi@ti.com>
> > Signed-off-by: Felipe Balbi <balbi@ti.com>
> > Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
>
> This was requested for 3.17+, although commit 7628083227b6 went into
> 3.11. Does it need backporting for 3.11-3.16 or will it work without
> changes?
>

Yeah, I haven't check all the stable trees, but I believe it was
already included in most of them already. Here's the discussion:

https://lkml.org/lkml/2014/11/19/377

Cheers,
--
Luís

> Ben.
>
> > ---
> > drivers/usb/gadget/at91_udc.c | 44 +++++++++++++++++++++++++++++++------------
> > 1 file changed, 32 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/usb/gadget/at91_udc.c b/drivers/usb/gadget/at91_udc.c
> > index cfd18bcca723..0d685d0b858e 100644
> > --- a/drivers/usb/gadget/at91_udc.c
> > +++ b/drivers/usb/gadget/at91_udc.c
> > @@ -870,12 +870,10 @@ static void clk_on(struct at91_udc *udc)
> > return;
> > udc->clocked = 1;
> >
> > - if (IS_ENABLED(CONFIG_COMMON_CLK)) {
> > - clk_set_rate(udc->uclk, 48000000);
> > - clk_prepare_enable(udc->uclk);
> > - }
> > - clk_prepare_enable(udc->iclk);
> > - clk_prepare_enable(udc->fclk);
> > + if (IS_ENABLED(CONFIG_COMMON_CLK))
> > + clk_enable(udc->uclk);
> > + clk_enable(udc->iclk);
> > + clk_enable(udc->fclk);
> > }
> >
> > static void clk_off(struct at91_udc *udc)
> > @@ -884,10 +882,10 @@ 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);
> > }
> >
> > /*
> > @@ -1780,14 +1778,24 @@ static int at91udc_probe(struct platform_device *pdev)
> > }
> >
> > /* don't do anything until we have both gadget driver and VBUS */
> > + if (IS_ENABLED(CONFIG_COMMON_CLK)) {
> > + clk_set_rate(udc->uclk, 48000000);
> > + retval = clk_prepare(udc->uclk);
> > + if (retval)
> > + goto fail1;
> > + }
> > + retval = clk_prepare(udc->fclk);
> > + if (retval)
> > + goto fail1a;
> > +
> > retval = clk_prepare_enable(udc->iclk);
> > if (retval)
> > - goto fail1;
> > + goto fail1b;
> > at91_udp_write(udc, AT91_UDP_TXVC, AT91_UDP_TXVC_TXVDIS);
> > at91_udp_write(udc, AT91_UDP_IDR, 0xffffffff);
> > /* Clear all pending interrupts - UDP may be used by bootloader. */
> > at91_udp_write(udc, AT91_UDP_ICR, 0xffffffff);
> > - clk_disable_unprepare(udc->iclk);
> > + clk_disable(udc->iclk);
> >
> > /* request UDC and maybe VBUS irqs */
> > udc->udp_irq = platform_get_irq(pdev, 0);
> > @@ -1795,7 +1803,7 @@ static int at91udc_probe(struct platform_device *pdev)
> > 0, driver_name, udc);
> > if (retval < 0) {
> > DBG("request irq %d failed\n", udc->udp_irq);
> > - goto fail1;
> > + goto fail1c;
> > }
> > if (gpio_is_valid(udc->board.vbus_pin)) {
> > retval = gpio_request(udc->board.vbus_pin, "udc_vbus");
> > @@ -1848,6 +1856,13 @@ fail3:
> > gpio_free(udc->board.vbus_pin);
> > fail2:
> > free_irq(udc->udp_irq, udc);
> > +fail1c:
> > + clk_unprepare(udc->iclk);
> > +fail1b:
> > + clk_unprepare(udc->fclk);
> > +fail1a:
> > + if (IS_ENABLED(CONFIG_COMMON_CLK))
> > + clk_unprepare(udc->uclk);
> > fail1:
> > if (IS_ENABLED(CONFIG_COMMON_CLK) && !IS_ERR(udc->uclk))
> > clk_put(udc->uclk);
> > @@ -1896,6 +1911,11 @@ static int __exit at91udc_remove(struct platform_device *pdev)
> > res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > release_mem_region(res->start, resource_size(res));
> >
> > + if (IS_ENABLED(CONFIG_COMMON_CLK))
> > + clk_unprepare(udc->uclk);
> > + clk_unprepare(udc->fclk);
> > + clk_unprepare(udc->iclk);
> > +
> > clk_put(udc->iclk);
> > clk_put(udc->fclk);
> > if (IS_ENABLED(CONFIG_COMMON_CLK))
>
> --
> Ben Hutchings
> The world is coming to an end. Please log off.