[PATCH 07/10] usb: Make sure that DWC2 initializes after the power channel mailbox driver.

[Lee Jones]

On Mon, 02 Mar 2015, Eric Anholt wrote:

> This gets USB working on the Raspberry Pi without relying on U-Boot to
> send the power message for us.  Without it, you would get warnings
> about fifo sizes and "dwc2_core_reset() HANG! Soft Reset
> GRSTCTL=80000001" leading to a failed probe.
> 
> Signed-off-by: Eric Anholt <eric at anholt.net>
> Cc: John Youn <johnyoun at synopsys.com>
> ---
>  drivers/mailbox/bcm2835-mailbox-power.c |  5 +++++
>  drivers/usb/dwc2/platform.c             | 20 ++++++++++++++++++++
>  2 files changed, 25 insertions(+)
> 
> diff --git a/drivers/mailbox/bcm2835-mailbox-power.c b/drivers/mailbox/bcm2835-mailbox-power.c
> index f09c855..d0faca2 100644
> --- a/drivers/mailbox/bcm2835-mailbox-power.c
> +++ b/drivers/mailbox/bcm2835-mailbox-power.c
> @@ -31,6 +31,9 @@ struct bcm_mbox_power {
>  	uint32_t response;
>  };
>  
> +bool bcm2835_mbox_power_initialized;
> +EXPORT_SYMBOL_GPL(bcm2835_mbox_power_initialized);

This is pretty ugly.  What is it used for?  Is there any way you can
use an API for it instead?

>  struct bcm_mbox_power *mbox_power;
>  
>  static void response_callback(struct mbox_client *cl, void *mssg)
> @@ -92,6 +95,7 @@ static int bcm2835_mbox_power_probe(struct platform_device *pdev)
>  		bcm_mbox_set_power(BCM_POWER_USB);
>  		bcm2835_mbox_power_initialized = true;
>  	}
> +	bcm2835_mbox_power_initialized = true;
>  
>  	return ret;
>  }
> @@ -99,6 +103,7 @@ static int bcm2835_mbox_power_probe(struct platform_device *pdev)
>  static int bcm2835_mbox_power_remove(struct platform_device *pdev)
>  {
>  	bcm_mbox_set_power(0);
> +	bcm2835_mbox_power_initialized = false;
>  
>  	mbox_free_channel(mbox_power->chan);
>  
> diff --git a/drivers/usb/dwc2/platform.c b/drivers/usb/dwc2/platform.c
> index ae095f0..2a4a3a6 100644
> --- a/drivers/usb/dwc2/platform.c
> +++ b/drivers/usb/dwc2/platform.c
> @@ -136,6 +136,20 @@ static const struct of_device_id dwc2_of_match_table[] = {
>  };
>  MODULE_DEVICE_TABLE(of, dwc2_of_match_table);
>  
> +extern bool bcm2835_mbox_power_initialized;

Ughhh, *shudder*.

> +bool bcm2835_usb_power_enabled(void)
> +{
> +#ifdef CONFIG_BCM2835_MBOX

Please don't put #ifdeffery in *.c files.  If you have to match on
CONFIG_* options, please do so using inlines in a header file
somewhere.

> +	return bcm2835_mbox_power_initialized;
> +#else
> +	/* Assume that somebody else has enabled the power for us
> +	 * (like U-Boot).
> +	 */
> +	return true;
> +#endif
> +}
> +
>  /**
>   * dwc2_driver_probe() - Called when the DWC_otg core is bound to the DWC_otg
>   * driver
> @@ -175,6 +189,12 @@ static int dwc2_driver_probe(struct platform_device *dev)
>  		defparams.dma_desc_enable = 0;
>  	}
>  
> +	/* Make sure the platform driver for enabling the power has
> +	 * initialized before we do.
> +	 */

This multi-line comment is unconventional.

See: Documentation/CodingStyle

> +	if (params == &params_bcm2835 && !bcm2835_usb_power_enabled())
> +		return -EPROBE_DEFER;

Why don't you cut out the middle man and get rid of all of these awful
exports?

include/linux/platform/bcm2835.h

#ifdef CONFIG_BCM2835_MBOX
static inline bool bcm2835_is_usb_powered()
{
	return bcm2835_mbox_is_usb_powered();
}
#else
static inline bool bcm2835_is_usb_powered()
{
	/* 
	 * If BCM2835 isn't using its Mailbox(es), the
	 * bootloader is charged with powering up USB.
	 */
	return true;
}
#endif 

>  	hsotg = devm_kzalloc(&dev->dev, sizeof(*hsotg), GFP_KERNEL);
>  	if (!hsotg)
>  		return -ENOMEM;