Re: [PATCH] usb: dwc3: add sprs_ctrl_trans_quirk

[Thinh Nguyen <Thinh.Nguyen@synopsys.com>]

Hi,

Yaqin Pan wrote:
> Add a quirk to set GUCTL.SPRSCTRLTRANSEN bit.
> 
> Some special peripherals can't handle the control transfer well.

Can you explain the problem in more detail?

> For example, TF card reader (aaaa:8816):
> usb 1-1: new high-speed USB device number 2 using xhci-hcd
> usb 1-1: device descriptor read/all, error -110
> From the usb analyzer, always return NAK in the data phase.

And how this change help to resolve this issue.

Also note in the patch that this is for host mode.

> 
> Signed-off-by: Yaqin Pan <akingchen@vivo.com>
> ---
>  drivers/usb/dwc3/core.c | 4 ++++
>  drivers/usb/dwc3/core.h | 3 +++
>  2 files changed, 7 insertions(+)
> 
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index ba74ad7f6995..93ac2c79a2c0 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -1071,6 +1071,8 @@ static int dwc3_core_init(struct dwc3 *dwc)
>  		 * packet with Retry=1 & Nump != 0)
>  		 */
>  		reg |= DWC3_GUCTL_HSTINAUTORETRY;
> +		if (dwc->sprs_ctrl_trans_quirk)
> +			reg |= DWC3_GUCTL_SPRSCTRLTRANSEN;
>  
>  		dwc3_writel(dwc->regs, DWC3_GUCTL, reg);
>  	}
> @@ -1377,6 +1379,8 @@ static void dwc3_get_properties(struct dwc3 *dwc)
>  
>  	dwc->dis_split_quirk = device_property_read_bool(dev,
>  				"snps,dis-split-quirk");
> +	dwc->sprs_ctrl_trans_quirk = device_property_read_bool(dev,
> +				"snps,sprs-ctrl-trans-quirk");

Since you're adding a new device property, please add another patch to
document it in Documentation/devicetree/bindings/usb

BR,
Thinh

>  
>  	dwc->lpm_nyet_threshold = lpm_nyet_threshold;
>  	dwc->tx_de_emphasis = tx_de_emphasis;
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index 5991766239ba..6048087df1d1 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -254,6 +254,7 @@
>  
>  /* Global User Control Register */
>  #define DWC3_GUCTL_HSTINAUTORETRY	BIT(14)
> +#define DWC3_GUCTL_SPRSCTRLTRANSEN	BIT(17)
>  
>  /* Global User Control 1 Register */
>  #define DWC3_GUCTL1_PARKMODE_DISABLE_SS	BIT(17)
> @@ -1077,6 +1078,7 @@ struct dwc3_scratchpad_array {
>   *	3	- Reserved
>   * @dis_metastability_quirk: set to disable metastability quirk.
>   * @dis_split_quirk: set to disable split boundary.
> + * @sprs_ctrl_trans_quirk: set to enable sparse control transaction quirk.
>   * @imod_interval: set the interrupt moderation interval in 250ns
>   *			increments or 0 to disable.
>   */
> @@ -1279,6 +1281,7 @@ struct dwc3 {
>  	unsigned		dis_metastability_quirk:1;
>  
>  	unsigned		dis_split_quirk:1;
> +	unsigned		sprs_ctrl_trans_quirk:1;
>  	unsigned		async_callbacks:1;
>  
>  	u16			imod_interval;
>