[U-Boot] [PATCH] sunxi: H3/H5/A64: OHCI: prevent turning off shared gates

[Marek Vasut]

On 07/03/2018 01:44 AM, Andre Przywara wrote:
> The USB host controllers on the H3, H5 and A64 have the oddity of
> sharing some clock and reset gates, so both the OHCI and EHCI bits have
> to be enabled to make only one of them working. We take care of this, and
> initialisation works fine (due to setting already set bits).
> However on shutdown we turn the clocks and reset gates off already when
> deregistering one controller, so the other one is no longer functional.
> In the result U-Boot complains just before launching the kernel and
> then hangs.
> Fix this by not turning off the clocks and resets on the OHCI side, so
> that the EHCI controller has a chance to properly shut down.
> This still isn't perfect, but at least prevents the hang.
> 
> Signed-off-by: Andre Przywara <andre.przywara at arm.com>

What about adding some enable/disable counter to those clock somehow and
then turning them off when the counter reaches zero ?

> ---
> Hi,
> 
> commit b62cdbddedc3 ("sunxi: clock: Fix EHCI and OHCI clocks on A64")
> introduced the proper reset and clock gates for the A64. While the patch
> itself is correct, it broke Linux as soon as one actually enables USB0 in
> the DT (in the moment we keep this "disabled" in U-Boot's DT version).
> 
> I understand that this patch here is somewhat of a hack, but the proper
> ref-counting is not easy to implement between the separate EHCI and OHCI
> drivers. Those two files are doomed anyway, since driver model clocks
> and reset drivers are already on the horizon:
> https://github.com/apritzel/u-boot/commits/sunxi-dm-WIP
> So lets fix this up for now so that we can use the Linux kernel DTs with
> U-Boot itself.
> 
> Cheers,
> Andre.
> 
>  drivers/usb/host/ohci-sunxi.c | 16 ++++++++++++----
>  1 file changed, 12 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/usb/host/ohci-sunxi.c b/drivers/usb/host/ohci-sunxi.c
> index 0ddbdbe460..42ffb6cbcb 100644
> --- a/drivers/usb/host/ohci-sunxi.c
> +++ b/drivers/usb/host/ohci-sunxi.c
> @@ -128,10 +128,18 @@ static int ohci_usb_remove(struct udevice *dev)
>  	if (ret)
>  		return ret;
>  
> -	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);
> -	clrbits_le32(&priv->ccm->ahb_gate0, priv->ahb_gate_mask);
> +	/*
> +	 * For those SoCs that share the clock and reset gates with the EHCI
> +	 * controller, we should not turn them off here, to prevent the
> +	 * other one hanging (when the EHCI driver tries to shut itself down).
> +	 */
> +	if (!priv->cfg->extra_ahb_gate_mask) {
> +		if (priv->cfg->has_reset)
> +			clrbits_le32(priv->reset0_cfg, priv->ahb_gate_mask);
> +		clrbits_le32(&priv->ccm->ahb_gate0, priv->ahb_gate_mask);
> +	}
> +	if (!priv->cfg->extra_usb_gate_mask)
> +		clrbits_le32(&priv->ccm->usb_clk_cfg, priv->usb_gate_mask);
>  
>  	return 0;
>  }
> 


-- 
Best regards,
Marek Vasut