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

[Luis Henriques <luis.henriques@canonical.com>]

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,
--
Lu�s

> 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.