Re: [PATCH] usb: xhci-dwc3: Bail out if "dr_mode" is "peripheral"

[Mattijs Korpershoek <mkorpershoek@baylibre.com>]

Hi Siddharth,

On lun., déc. 09, 2024 at 15:20, Roger Quadros <rogerq@kernel.org> wrote:

> Hi Siddharth,
>
> On 06/12/2024 13:04, Siddharth Vadapalli wrote:
>> Since the compatible "snps,dwc3" can be specified in the device-tree for
>> the Designware USB Controller configured for not only Host and OTG modes
>> of operation, but also for Peripheral mode of operation, bail out if
>> "dr_mode" is "peripheral".
>> 
>> Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
>> ---
>> 
>> Hello,
>> 
>> This patch is based on commit
>> 448add55297 Merge branch 'master' of https://source.denx.de/u-boot/custodians/u-boot-pmic
>> of the master branch of U-Boot.
>> 
>> Regards,
>> Siddharth.
>> 
>>  drivers/usb/host/xhci-dwc3.c | 3 +++
>>  1 file changed, 3 insertions(+)
>> 
>> diff --git a/drivers/usb/host/xhci-dwc3.c b/drivers/usb/host/xhci-dwc3.c
>> index e3e0ceff43e..7b1311503fe 100644
>> --- a/drivers/usb/host/xhci-dwc3.c
>> +++ b/drivers/usb/host/xhci-dwc3.c
>> @@ -208,6 +208,9 @@ static int xhci_dwc3_probe(struct udevice *dev)
>>  	writel(reg, &dwc3_reg->g_usb2phycfg[0]);
>>  
>>  	dr_mode = usb_get_dr_mode(dev_ofnode(dev));
>> +	if (dr_mode == USB_DR_MODE_PERIPHERAL)
>> +		return -ENODEV;
>> +
>>  	if (dr_mode == USB_DR_MODE_OTG &&
>>  	    dev_read_bool(dev, "usb-role-switch")) {
>>  		dr_mode = usb_get_role_switch_default_mode(dev_ofnode(dev));
>
> Although this proposal was suggested in [1] and later clarified in
> [2] I will summarize the discussion here.
>
> This patch fix is not sufficient for all cases as the xhci-dwc3.c
> driver will still be probed if dr_mode is OTG or HOST along with
> other platform drivers if enabled in config.
>
> The only current solution is not not enable CONFIG_USB_XHCI_DWC3
> together with another platform driver config (e.g. CONFIG_USB_DWC3_GENERIC)
> if snps,dwc3 should not be managed by xhci-dwc3.c.

Given Roger's explanation, should we simply drop this, or is any other
action expected from the U-Boot maintainers?

Thanks,
Mattijs

>
> [1] - https://lore.kernel.org/all/unf757pwgah5ylkcfdumtdo5zs2ny3nxct5u26t6up7aldqim2@mxhhtb53gw4x/
> [2] - https://lore.kernel.org/all/a9c458f8-68e5-448b-9977-e7bf37b00d35@kernel.org/
>
> -- 
> cheers,
> -roger