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

Ben Hutchings
2015-01-14T13:37:59Z

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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?

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
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