[PATCH] usb: gadget: Fix trb_virt_to_phys() error value

[PATCH] usb: gadget: Fix trb_virt_to_phys() error value

[Thomas Fourier]

0 is a valid DMA address, so returning DMA_MAPPING_ERROR in
trb_virt_to_phys().  Also, dma_mapping_error() wouldn't
flag 0 as an error address.
Checking the return value directly because the dma_addr
does not come directly from dma_map().

Fixes: 49db427232fe ("usb: gadget: Add UDC driver for tegra XUSB device mode controller")
Signed-off-by: Thomas Fourier <fourier.thomas@gmail.com>
---
 drivers/usb/gadget/udc/tegra-xudc.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/gadget/udc/tegra-xudc.c b/drivers/usb/gadget/udc/tegra-xudc.c
index 2957316fd3d0..5dd3452bddbc 100644
--- a/drivers/usb/gadget/udc/tegra-xudc.c
+++ b/drivers/usb/gadget/udc/tegra-xudc.c
@@ -900,7 +900,7 @@ static dma_addr_t trb_virt_to_phys(struct tegra_xudc_ep *ep,
 	index = trb - ep->transfer_ring;
 
 	if (WARN_ON(index >= XUDC_TRANSFER_RING_SIZE))
-		return 0;
+		return DMA_MAPPING_ERROR;
 
 	return (ep->transfer_ring_phys + index * sizeof(*trb));
 }
@@ -1480,7 +1480,7 @@ __tegra_xudc_ep_dequeue(struct tegra_xudc_ep *ep,
 			deq_ptr = trb_virt_to_phys(ep,
 					&ep->transfer_ring[ep->enq_ptr]);
 
-			if (dma_mapping_error(xudc->dev, deq_ptr)) {
+			if (deq_ptr == DMA_MAPPING_ERROR) {
 				ret = -EINVAL;
 			} else {
 				ep_ctx_write_deq_ptr(ep->context, deq_ptr);
@@ -2836,7 +2836,7 @@ static void tegra_xudc_reset(struct tegra_xudc *xudc)
 
 	deq_ptr = trb_virt_to_phys(ep0, &ep0->transfer_ring[ep0->deq_ptr]);
 
-	if (!dma_mapping_error(xudc->dev, deq_ptr)) {
+	if (deq_ptr != DMA_MAPPING_ERROR) {
 		ep_ctx_write_deq_ptr(ep0->context, deq_ptr);
 		ep_ctx_write_dcs(ep0->context, ep0->pcs);
 	}
-- 
2.43.0

Re: [PATCH] usb: gadget: Fix trb_virt_to_phys() error value

[Greg Kroah-Hartman]

On Fri, Jul 25, 2025 at 11:05:33AM +0200, Thomas Fourier wrote:
> 0 is a valid DMA address, so returning DMA_MAPPING_ERROR in
> trb_virt_to_phys().  Also, dma_mapping_error() wouldn't
> flag 0 as an error address.
> Checking the return value directly because the dma_addr
> does not come directly from dma_map().
> 
> Fixes: 49db427232fe ("usb: gadget: Add UDC driver for tegra XUSB device mode controller")
> Signed-off-by: Thomas Fourier <fourier.thomas@gmail.com>
> ---
>  drivers/usb/gadget/udc/tegra-xudc.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/usb/gadget/udc/tegra-xudc.c b/drivers/usb/gadget/udc/tegra-xudc.c
> index 2957316fd3d0..5dd3452bddbc 100644
> --- a/drivers/usb/gadget/udc/tegra-xudc.c
> +++ b/drivers/usb/gadget/udc/tegra-xudc.c
> @@ -900,7 +900,7 @@ static dma_addr_t trb_virt_to_phys(struct tegra_xudc_ep *ep,
>  	index = trb - ep->transfer_ring;
>  
>  	if (WARN_ON(index >= XUDC_TRANSFER_RING_SIZE))
> -		return 0;
> +		return DMA_MAPPING_ERROR;
>  
>  	return (ep->transfer_ring_phys + index * sizeof(*trb));
>  }
> @@ -1480,7 +1480,7 @@ __tegra_xudc_ep_dequeue(struct tegra_xudc_ep *ep,
>  			deq_ptr = trb_virt_to_phys(ep,
>  					&ep->transfer_ring[ep->enq_ptr]);
>  
> -			if (dma_mapping_error(xudc->dev, deq_ptr)) {
> +			if (deq_ptr == DMA_MAPPING_ERROR) {
>  				ret = -EINVAL;
>  			} else {
>  				ep_ctx_write_deq_ptr(ep->context, deq_ptr);
> @@ -2836,7 +2836,7 @@ static void tegra_xudc_reset(struct tegra_xudc *xudc)
>  
>  	deq_ptr = trb_virt_to_phys(ep0, &ep0->transfer_ring[ep0->deq_ptr]);
>  
> -	if (!dma_mapping_error(xudc->dev, deq_ptr)) {
> +	if (deq_ptr != DMA_MAPPING_ERROR) {
>  		ep_ctx_write_deq_ptr(ep0->context, deq_ptr);
>  		ep_ctx_write_dcs(ep0->context, ep0->pcs);
>  	}
> -- 
> 2.43.0
> 
> 

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
a patch that has triggered this response.  He used to manually respond
to these common problems, but in order to save his sanity (he kept
writing the same thing over and over, yet to different people), I was
created.  Hopefully you will not take offence and will fix the problem
in your patch and resubmit it so that it can be accepted into the Linux
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You are receiving this message because of the following common error(s)
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