[PATCH v2] usb: dwc3: core: Fix timeout check

[PATCH v2] usb: dwc3: core: Fix timeout check

[Varadarajan Narayanan]

dwc3_core_init loops 'timeout' times to check if the IP block is out
of reset using 'while (timeout--)'. If there is some issue and
the block doesn't come out of reset, the loop will run till
'timeout' becomes zero and the post decrement operator would set
timeout to 0xffffffff. Though the IP block is not out reset, the
subsequent if check 'if !timeout' would fail as timeout is not
equal to zero and the function proceeds with the initialization.

Use poll API instead to resolve this.

Tested-By: Varadarajan Narayanan <quic_varada@quicinc.com>
Signed-off-by: Varadarajan Narayanan <quic_varada@quicinc.com>
---
v2: * Use poll API and remove the timeout variable based loop as
      suggested by 'Marek Vasut'
    * Drop 'Reviewed-by: Neil Armstrong' as the patch has taken
      a very different shape
---
 drivers/usb/dwc3/core.c | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index a35b8c2f64..847fa1f82c 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -23,6 +23,7 @@
 #include <linux/delay.h>
 #include <linux/dma-mapping.h>
 #include <linux/err.h>
+#include <linux/iopoll.h>
 #include <linux/ioport.h>
 #include <dm.h>
 #include <generic-phy.h>
@@ -587,7 +588,6 @@ static void dwc3_set_incr_burst_type(struct dwc3 *dwc)
  */
 static int dwc3_core_init(struct dwc3 *dwc)
 {
-	unsigned long		timeout;
 	u32			hwparams4 = dwc->hwparams.hwparams4;
 	u32			reg;
 	int			ret;
@@ -610,15 +610,11 @@ static int dwc3_core_init(struct dwc3 *dwc)
 	}
 
 	/* issue device SoftReset too */
-	timeout = 5000;
 	dwc3_writel(dwc->regs, DWC3_DCTL, DWC3_DCTL_CSFTRST);
-	while (timeout--) {
-		reg = dwc3_readl(dwc->regs, DWC3_DCTL);
-		if (!(reg & DWC3_DCTL_CSFTRST))
-			break;
-	};
-
-	if (!timeout) {
+	ret = read_poll_timeout(dwc3_readl, reg,
+				!(reg & DWC3_DCTL_CSFTRST),
+				1, 5000, dwc->regs, DWC3_DCTL);
+	if (ret) {
 		dev_err(dwc->dev, "Reset Timed Out\n");
 		ret = -ETIMEDOUT;
 		goto err0;
-- 
2.34.1

Re: [PATCH v2] usb: dwc3: core: Fix timeout check

[Mattijs Korpershoek]

Hi Varadarajan,

Thank you for the patch.

On mer., janv. 15, 2025 at 11:50, Varadarajan Narayanan <quic_varada@quicinc.com> wrote:

> dwc3_core_init loops 'timeout' times to check if the IP block is out
> of reset using 'while (timeout--)'. If there is some issue and
> the block doesn't come out of reset, the loop will run till
> 'timeout' becomes zero and the post decrement operator would set
> timeout to 0xffffffff. Though the IP block is not out reset, the
> subsequent if check 'if !timeout' would fail as timeout is not
> equal to zero and the function proceeds with the initialization.
>
> Use poll API instead to resolve this.
>
> Tested-By: Varadarajan Narayanan <quic_varada@quicinc.com>

s/Tested-By/Tested-by

See ./scripts/checkpatch.pl:

λ ~/work/upstream/src/u-boot/ varadarajan/dwc3-timeout ./scripts/checkpatch.pl --u-boot --git HEAD^..HEAD
WARNING: 'Tested-by:' is the preferred signature form
#16:
Tested-By: Varadarajan Narayanan <quic_varada@quicinc.com>

total: 0 errors, 1 warnings, 0 checks, 33 lines checked

> Signed-off-by: Varadarajan Narayanan <quic_varada@quicinc.com>

I think Marek can fix-up that when he applies, but if you send a v3 to
correct this, feel free to add:

Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>

Thanks
Mattijs

> ---
> v2: * Use poll API and remove the timeout variable based loop as
>       suggested by 'Marek Vasut'
>     * Drop 'Reviewed-by: Neil Armstrong' as the patch has taken
>       a very different shape
> ---
>  drivers/usb/dwc3/core.c | 14 +++++---------
>  1 file changed, 5 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index a35b8c2f64..847fa1f82c 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -23,6 +23,7 @@
>  #include <linux/delay.h>
>  #include <linux/dma-mapping.h>
>  #include <linux/err.h>
> +#include <linux/iopoll.h>
>  #include <linux/ioport.h>
>  #include <dm.h>
>  #include <generic-phy.h>
> @@ -587,7 +588,6 @@ static void dwc3_set_incr_burst_type(struct dwc3 *dwc)
>   */
>  static int dwc3_core_init(struct dwc3 *dwc)
>  {
> -	unsigned long		timeout;
>  	u32			hwparams4 = dwc->hwparams.hwparams4;
>  	u32			reg;
>  	int			ret;
> @@ -610,15 +610,11 @@ static int dwc3_core_init(struct dwc3 *dwc)
>  	}
>  
>  	/* issue device SoftReset too */
> -	timeout = 5000;
>  	dwc3_writel(dwc->regs, DWC3_DCTL, DWC3_DCTL_CSFTRST);
> -	while (timeout--) {
> -		reg = dwc3_readl(dwc->regs, DWC3_DCTL);
> -		if (!(reg & DWC3_DCTL_CSFTRST))
> -			break;
> -	};
> -
> -	if (!timeout) {
> +	ret = read_poll_timeout(dwc3_readl, reg,
> +				!(reg & DWC3_DCTL_CSFTRST),
> +				1, 5000, dwc->regs, DWC3_DCTL);
> +	if (ret) {
>  		dev_err(dwc->dev, "Reset Timed Out\n");
>  		ret = -ETIMEDOUT;
>  		goto err0;
> -- 
> 2.34.1

Re: [PATCH v2] usb: dwc3: core: Fix timeout check

[Marek Vasut]

On 1/16/25 10:31 AM, Mattijs Korpershoek wrote:
> Hi Varadarajan,
> 
> Thank you for the patch.
> 
> On mer., janv. 15, 2025 at 11:50, Varadarajan Narayanan <quic_varada@quicinc.com> wrote:
> 
>> dwc3_core_init loops 'timeout' times to check if the IP block is out
>> of reset using 'while (timeout--)'. If there is some issue and
>> the block doesn't come out of reset, the loop will run till
>> 'timeout' becomes zero and the post decrement operator would set
>> timeout to 0xffffffff. Though the IP block is not out reset, the
>> subsequent if check 'if !timeout' would fail as timeout is not
>> equal to zero and the function proceeds with the initialization.
>>
>> Use poll API instead to resolve this.
>>
>> Tested-By: Varadarajan Narayanan <quic_varada@quicinc.com>
> 
> s/Tested-By/Tested-by
> 
> See ./scripts/checkpatch.pl:
> 
> λ ~/work/upstream/src/u-boot/ varadarajan/dwc3-timeout ./scripts/checkpatch.pl --u-boot --git HEAD^..HEAD
> WARNING: 'Tested-by:' is the preferred signature form
> #16:
> Tested-By: Varadarajan Narayanan <quic_varada@quicinc.com>
> 
> total: 0 errors, 1 warnings, 0 checks, 33 lines checked
> 
>> Signed-off-by: Varadarajan Narayanan <quic_varada@quicinc.com>
> 
> I think Marek can fix-up that when he applies, but if you send a v3 to
> correct this, feel free to add:
TB by author is a bit odd, so I dropped both TBs and kept RBs only.

Re: [PATCH v2] usb: dwc3: core: Fix timeout check

[Caleb Connolly]

On 15/01/2025 07:20, Varadarajan Narayanan wrote:
> dwc3_core_init loops 'timeout' times to check if the IP block is out
> of reset using 'while (timeout--)'. If there is some issue and
> the block doesn't come out of reset, the loop will run till
> 'timeout' becomes zero and the post decrement operator would set
> timeout to 0xffffffff. Though the IP block is not out reset, the
> subsequent if check 'if !timeout' would fail as timeout is not
> equal to zero and the function proceeds with the initialization.

Nice catch, this is a nasty one.
> 
> Use poll API instead to resolve this.
> 
> Tested-By: Varadarajan Narayanan <quic_varada@quicinc.com>
> Signed-off-by: Varadarajan Narayanan <quic_varada@quicinc.com>

Reviewed-by: Caleb Connolly <caleb.connolly@linaro.org>
> ---
> v2: * Use poll API and remove the timeout variable based loop as
>       suggested by 'Marek Vasut'
>     * Drop 'Reviewed-by: Neil Armstrong' as the patch has taken
>       a very different shape
> ---
>  drivers/usb/dwc3/core.c | 14 +++++---------
>  1 file changed, 5 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index a35b8c2f64..847fa1f82c 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -23,6 +23,7 @@
>  #include <linux/delay.h>
>  #include <linux/dma-mapping.h>
>  #include <linux/err.h>
> +#include <linux/iopoll.h>
>  #include <linux/ioport.h>
>  #include <dm.h>
>  #include <generic-phy.h>
> @@ -587,7 +588,6 @@ static void dwc3_set_incr_burst_type(struct dwc3 *dwc)
>   */
>  static int dwc3_core_init(struct dwc3 *dwc)
>  {
> -	unsigned long		timeout;
>  	u32			hwparams4 = dwc->hwparams.hwparams4;
>  	u32			reg;
>  	int			ret;
> @@ -610,15 +610,11 @@ static int dwc3_core_init(struct dwc3 *dwc)
>  	}
>  
>  	/* issue device SoftReset too */
> -	timeout = 5000;
>  	dwc3_writel(dwc->regs, DWC3_DCTL, DWC3_DCTL_CSFTRST);
> -	while (timeout--) {
> -		reg = dwc3_readl(dwc->regs, DWC3_DCTL);
> -		if (!(reg & DWC3_DCTL_CSFTRST))
> -			break;
> -	};
> -
> -	if (!timeout) {
> +	ret = read_poll_timeout(dwc3_readl, reg,
> +				!(reg & DWC3_DCTL_CSFTRST),
> +				1, 5000, dwc->regs, DWC3_DCTL);
> +	if (ret) {
>  		dev_err(dwc->dev, "Reset Timed Out\n");
>  		ret = -ETIMEDOUT;
>  		goto err0;

-- 
// Caleb (they/them)