On targets using synopsys usb dwc3 controller, it is observed while testing
multiple audio devices, a glitch is observed during testing.
As per dwc datasheet,By default, HC reserves 80% of the bandwidth
for periodic EPs which can be increased with GUCTL Bit 16.

Add quirk to set GUCTL register BIT 16 to accommodate higher
bandwidth for 2 isoc eps.

If this bit is set, the bandwidth is relaxed to 85% to
accommodate two high speed, high bandwidth ISOC EPs.
USB 2.0 required 80% bandwidth allocated for ISOC traffic. If
two High-bandwidth ISOC devices (HD Webcams) are
connected, and if each requires 1024-bytes X 3 packets per
Micro-Frame, then the bandwidth required is around 82%. If
this bit is set, then it is possible to connect two Webcams of
1024bytes X 3 paylod per Micro-Frame each. Alternatively, you
might need to lower the resolution of the webcams.
This bit is valid in Host and DRD configuration and is used in
host mode operation only.
Set this bit for host mode uvc uac usecases where two isoc eps
are used and flicker is seen.

Signed-off-by: Akash Kumar <quic_akakum@quicinc.com>
---
 drivers/usb/dwc3/core.c | 11 +++++++++++
 drivers/usb/dwc3/core.h |  4 ++++
 2 files changed, 15 insertions(+)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index dfa1b5fe48dc..7e55c234e4e5 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -1461,6 +1461,14 @@ static int dwc3_core_init(struct dwc3 *dwc)
 		dwc3_writel(dwc->regs, DWC3_GUCTL1, reg);
 	}
 
+	if (dwc->revision >= DWC3_REVISION_250A) {
+		if (dwc->dwc3_guctl_resbwhseps_quirk) {
+			reg = dwc3_readl(dwc->regs, DWC3_GUCTL);
+			reg |= DWC3_GUCTL_RESBWHSEPS;
+			dwc3_writel(dwc->regs, DWC3_GUCTL, reg);
+		}
+	}
+
 	dwc3_config_threshold(dwc);
 
 	/*
@@ -1818,6 +1826,9 @@ static void dwc3_get_properties(struct dwc3 *dwc)
 	dwc->dis_split_quirk = device_property_read_bool(dev,
 				"snps,dis-split-quirk");
 
+	dwc->dwc3_guctl_resbwhseps_quirk = device_property_read_bool(dev,
+				"snps,dwc3_guctl_resbwhseps_quirk");
+
 	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 ac7c730f81ac..00f4582edfca 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -283,6 +283,9 @@
 #define DWC3_GUCTL1_PARKMODE_DISABLE_HS		BIT(16)
 #define DWC3_GUCTL1_RESUME_OPMODE_HS_HOST	BIT(10)
 
+/* Global User Control Register */
+#define DWC3_GUCTL_RESBWHSEPS			BIT(16)
+
 /* Global Status Register */
 #define DWC3_GSTS_OTG_IP	BIT(10)
 #define DWC3_GSTS_BC_IP		BIT(9)
@@ -1393,6 +1396,7 @@ struct dwc3 {
 	int			num_ep_resized;
 	struct dentry		*debug_root;
 	u32			gsbuscfg0_reqinfo;
+	bool			dwc3_guctl_resbwhseps_quirk;
 };
 
 #define INCRX_BURST_MODE 0
-- 
2.17.1

On 06/02/2025 12:15, Akash Kumar wrote:
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index dfa1b5fe48dc..7e55c234e4e5 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -1461,6 +1461,14 @@ static int dwc3_core_init(struct dwc3 *dwc)
>  		dwc3_writel(dwc->regs, DWC3_GUCTL1, reg);
>  	}
>  
> +	if (dwc->revision >= DWC3_REVISION_250A) {
> +		if (dwc->dwc3_guctl_resbwhseps_quirk) {
> +			reg = dwc3_readl(dwc->regs, DWC3_GUCTL);
> +			reg |= DWC3_GUCTL_RESBWHSEPS;
> +			dwc3_writel(dwc->regs, DWC3_GUCTL, reg);
> +		}
> +	}
> +
>  	dwc3_config_threshold(dwc);
>  
>  	/*
> @@ -1818,6 +1826,9 @@ static void dwc3_get_properties(struct dwc3 *dwc)
>  	dwc->dis_split_quirk = device_property_read_bool(dev,
>  				"snps,dis-split-quirk");
>  
> +	dwc->dwc3_guctl_resbwhseps_quirk = device_property_read_bool(dev,
> +				"snps,dwc3_guctl_resbwhseps_quirk");

NAK, undocumented ABI, not even bothering to follow standard DTS coding
style.

Best regards,
Krzysztof

On 6.02.2025 12:15 PM, Akash Kumar wrote:
> On targets using synopsys usb dwc3 controller, it is observed while testing
> multiple audio devices, a glitch is observed during testing.
> As per dwc datasheet,By default, HC reserves 80% of the bandwidth
> for periodic EPs which can be increased with GUCTL Bit 16.

It is observed a glitch is observed.. please massage this paragraph
a bit.

> 
> Add quirk to set GUCTL register BIT 16 to accommodate higher
> bandwidth for 2 isoc eps.
> 
> If this bit is set, the bandwidth is relaxed to 85% to
> accommodate two high speed, high bandwidth ISOC EPs.
> USB 2.0 required 80% bandwidth allocated for ISOC traffic. If
> two High-bandwidth ISOC devices (HD Webcams) are
> connected, and if each requires 1024-bytes X 3 packets per
> Micro-Frame, then the bandwidth required is around 82%. If
> this bit is set, then it is possible to connect two Webcams of
> 1024bytes X 3 paylod per Micro-Frame each. Alternatively, you
> might need to lower the resolution of the webcams.
> This bit is valid in Host and DRD configuration and is used in
> host mode operation only.
> Set this bit for host mode uvc uac usecases where two isoc eps
> are used and flicker is seen.

Re-format your commit text to wrap at ~72 characters
> 
> Signed-off-by: Akash Kumar <quic_akakum@quicinc.com>
> ---
>  drivers/usb/dwc3/core.c | 11 +++++++++++
>  drivers/usb/dwc3/core.h |  4 ++++
>  2 files changed, 15 insertions(+)
> 
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index dfa1b5fe48dc..7e55c234e4e5 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -1461,6 +1461,14 @@ static int dwc3_core_init(struct dwc3 *dwc)
>  		dwc3_writel(dwc->regs, DWC3_GUCTL1, reg);
>  	}
>  
> +	if (dwc->revision >= DWC3_REVISION_250A) {
> +		if (dwc->dwc3_guctl_resbwhseps_quirk) {
> +			reg = dwc3_readl(dwc->regs, DWC3_GUCTL);
> +			reg |= DWC3_GUCTL_RESBWHSEPS;
> +			dwc3_writel(dwc->regs, DWC3_GUCTL, reg);
> +		}
> +	}
> +
>  	dwc3_config_threshold(dwc);
>  
>  	/*
> @@ -1818,6 +1826,9 @@ static void dwc3_get_properties(struct dwc3 *dwc)
>  	dwc->dis_split_quirk = device_property_read_bool(dev,
>  				"snps,dis-split-quirk");
>  
> +	dwc->dwc3_guctl_resbwhseps_quirk = device_property_read_bool(dev,
> +				"snps,dwc3_guctl_resbwhseps_quirk");

This needs a dt-bindings entry. Also, underscores are forbidden in property
names, use hyphens instead.

Konrad

Hi,

On 2/6/2025 11:19 PM, Konrad Dybcio wrote:
> On 6.02.2025 12:15 PM, Akash Kumar wrote:
>> On targets using synopsys usb dwc3 controller, it is observed while testing
>> multiple audio devices, a glitch is observed during testing.
>> As per dwc datasheet,By default, HC reserves 80% of the bandwidth
>> for periodic EPs which can be increased with GUCTL Bit 16.
> It is observed a glitch is observed.. please massage this paragraph
> a bit.
Sure.
>
>> Add quirk to set GUCTL register BIT 16 to accommodate higher
>> bandwidth for 2 isoc eps.
>>
>> If this bit is set, the bandwidth is relaxed to 85% to
>> accommodate two high speed, high bandwidth ISOC EPs.
>> USB 2.0 required 80% bandwidth allocated for ISOC traffic. If
>> two High-bandwidth ISOC devices (HD Webcams) are
>> connected, and if each requires 1024-bytes X 3 packets per
>> Micro-Frame, then the bandwidth required is around 82%. If
>> this bit is set, then it is possible to connect two Webcams of
>> 1024bytes X 3 paylod per Micro-Frame each. Alternatively, you
>> might need to lower the resolution of the webcams.
>> This bit is valid in Host and DRD configuration and is used in
>> host mode operation only.
>> Set this bit for host mode uvc uac usecases where two isoc eps
>> are used and flicker is seen.
> Re-format your commit text to wrap at ~72 characters
Ok.
>> Signed-off-by: Akash Kumar <quic_akakum@quicinc.com>
>> ---
>>   drivers/usb/dwc3/core.c | 11 +++++++++++
>>   drivers/usb/dwc3/core.h |  4 ++++
>>   2 files changed, 15 insertions(+)
>>
>> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
>> index dfa1b5fe48dc..7e55c234e4e5 100644
>> --- a/drivers/usb/dwc3/core.c
>> +++ b/drivers/usb/dwc3/core.c
>> @@ -1461,6 +1461,14 @@ static int dwc3_core_init(struct dwc3 *dwc)
>>   		dwc3_writel(dwc->regs, DWC3_GUCTL1, reg);
>>   	}
>>   
>> +	if (dwc->revision >= DWC3_REVISION_250A) {
>> +		if (dwc->dwc3_guctl_resbwhseps_quirk) {
>> +			reg = dwc3_readl(dwc->regs, DWC3_GUCTL);
>> +			reg |= DWC3_GUCTL_RESBWHSEPS;
>> +			dwc3_writel(dwc->regs, DWC3_GUCTL, reg);
>> +		}
>> +	}
>> +
>>   	dwc3_config_threshold(dwc);
>>   
>>   	/*
>> @@ -1818,6 +1826,9 @@ static void dwc3_get_properties(struct dwc3 *dwc)
>>   	dwc->dis_split_quirk = device_property_read_bool(dev,
>>   				"snps,dis-split-quirk");
>>   
>> +	dwc->dwc3_guctl_resbwhseps_quirk = device_property_read_bool(dev,
>> +				"snps,dwc3_guctl_resbwhseps_quirk");
> This needs a dt-bindings entry. Also, underscores are forbidden in property
> names, use hyphens instead.

Will update in V2.

Thanks

Akash