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

Lee Jones
2015-03-03T08:32:50Z

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-WhKQ6XTQaPysTnJN9+BGXg@public.gmane.org>
> Cc: John Youn <johnyoun-HKixBCOQz3hWk0Htik3J/w@public.gmane.org>
> ---
> 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;