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

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Date:	Wed, 14 Jan 2015 13:37:38 +0000
From:	Ben Hutchings <ben@...adent.org.uk>
To:	Luis Henriques <luis.henriques@...onical.com>,
	Ronald Wahl <ronald.wahl@...itan.com>,
	Felipe Balbi <balbi@...com>
Cc:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Subject: Re: [PATCH 3.16.y-ckt 040/216] usb: gadget: at91_udc: move prepare
 clk into process context

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@...itan.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@...itan.com>
> Acked-by: Alexandre Belloni <alexandre.belloni@...e-electrons.com>
> Acked-by: Boris Brezillon <boris.brezillon@...e-electrons.com>
> Acked-by: Nicolas Ferre <nicolas.ferre@...el.com>
> Cc: Felipe Balbi <balbi@...com>
> Signed-off-by: Felipe Balbi <balbi@...com>
> Signed-off-by: Luis Henriques <luis.henriques@...onical.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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