[U-Boot] [PATCH] sunxi: A64: OHCI: prevent turning off shared USB clock

[Marek Vasut]

On 07/04/2018 12:03 PM, Andre Przywara wrote:
> Hi,
> 
> On 04/07/18 08:14, Marek Vasut wrote:
>> On 07/04/2018 02:05 AM, Andre Przywara wrote:
>>> On the A64 the clock for the first USB controller is actually the parent
>>> of the clock for the second controller, so turning them off in that order
>>> makes the system hang.
>>> Fix this by *not* turning off any clock for OHCI0, but both clocks when
>>> OHCI1 is brought down.
>>>
>>> Signed-off-by: Andre Przywara <andre.przywara at arm.com>
>>> ---
>>> Hi,
>>>
>>> this is a new approach to fix the USB hang we see with mainline U-Boot.
>>> Compared to the previous patch it just deals with the USB clock (the AHB
>>> gate was a red herring), and it eventually turns both clocks off instead
>>> of leaving them running. Please have a test on A64 boards!
>>>
>>> Cheers,
>>> Andre.
>>>
>>>  drivers/usb/host/ohci-sunxi.c | 13 ++++++++++++-
>>>  1 file changed, 12 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/usb/host/ohci-sunxi.c b/drivers/usb/host/ohci-sunxi.c
>>> index 0ddbdbe460..8f108b48a8 100644
>>> --- a/drivers/usb/host/ohci-sunxi.c
>>> +++ b/drivers/usb/host/ohci-sunxi.c
>>> @@ -114,6 +114,7 @@ no_phy:
>>>  static int ohci_usb_remove(struct udevice *dev)
>>>  {
>>>  	struct ohci_sunxi_priv *priv = dev_get_priv(dev);
>>> +	fdt_addr_t base_addr = devfdt_get_addr(dev);
>>>  	int ret;
>>>  
>>>  	if (generic_phy_valid(&priv->phy)) {
>>> @@ -130,7 +131,17 @@ static int ohci_usb_remove(struct udevice *dev)
>>>  
>>>  	if (priv->cfg->has_reset)
>>>  		clrbits_le32(priv->reset0_cfg, priv->ahb_gate_mask);
>>> -	clrbits_le32(&priv->ccm->usb_clk_cfg, priv->usb_gate_mask);
>>> +	/*
>>> +	 * On the A64 CLK_USB_OHCI0 is the parent of CLK_USB_OHCI1, so
>>> +	 * we have to bring down none for OHCI0, but both for OHCI1.
>>> +	 */
>>> +	if (!priv->cfg->extra_usb_gate_mask || base_addr >= SUNXI_USB2_BASE) {
>>> +		u32 usb_gate_mask = priv->usb_gate_mask;
>>> +
>>> +		usb_gate_mask |= priv->cfg->extra_usb_gate_mask;
>>> +		clrbits_le32(&priv->ccm->usb_clk_cfg, usb_gate_mask);
>>> +	}
>>> +
>>>  	clrbits_le32(&priv->ccm->ahb_gate0, priv->ahb_gate_mask);
>>>  
>>>  	return 0;
>>>
>>
>> What about boards which only enable OHCI0 and do not enable OHCI1 ?
> 
> Ah, c'mon, thanks for spoiling my short patch ;-)
> The A64 has just two USB controllers, on dedicated pins, so mostly you
> want both of them. But I see your point, the clocks would stay on if
> only the first controller is ever dealt with. Maybe we can live with
> that, at least for the next release?
> Or do you have a clever idea how to deal with that? I think it's hard to
> determine how many USB controller we have enabled?

I'd prefer approach which works in all cases.

Can't you check if both controllers are enabled by traversing the DT ?

-- 
Best regards,
Marek Vasut