[U-Boot] [PATCH v2 5/7] usb: dwc2-otg: fix warnings for ep->dma_buf for LP64 builds

[Marek Vasut]

On 06/06/2017 03:42 PM, Philipp Tomsich wrote:
> For LP64 build w/ GCC 6.3, the handling of the ep->dma_buf variable
> when (truncating and) writing into the controller's registers is
> unsafe and triggers the following compiler warning (thus failing by
> buildman tests):
>   ../drivers/usb/gadget/dwc2_udc_otg_xfer_dma.c: In function 'setdma_rx':
>   ../drivers/usb/gadget/dwc2_udc_otg_xfer_dma.c:116:9: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
>     writel((unsigned int) ep->dma_buf, &reg->out_endp[ep_num].doepdma);
>            ^
> 
> This change fixes the warning and makes the code a bit more robust by
> doing the following:
> - we check whether ep->dma_buf can be safely truncated to 32 bits
>   (i.e. whether dma_buf is the same value when masked to 32 bits) and
>   emit an error message if that is not the case
> - we cast to a uintptr_t and let the writel macro truncate the
>   uintptr_t (potentially a 64bit value) to 32bits
> 
> Signed-off-by: Philipp Tomsich <philipp.tomsich at theobroma-systems.com>
> 
> ---
> 
> Changes in v2:
> - (new patch) fix warnings and add some robustness for the truncation
>   of ep->dma_buf in dwc2-otg for LP64 builds to fix a buildman failure
>   for u-boot-rockchip/master at 2b19b2f
> 
>  drivers/usb/gadget/dwc2_udc_otg_xfer_dma.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/gadget/dwc2_udc_otg_xfer_dma.c b/drivers/usb/gadget/dwc2_udc_otg_xfer_dma.c
> index 0d6d2fb..f5c926c 100644
> --- a/drivers/usb/gadget/dwc2_udc_otg_xfer_dma.c
> +++ b/drivers/usb/gadget/dwc2_udc_otg_xfer_dma.c
> @@ -113,7 +113,11 @@ static int setdma_rx(struct dwc2_ep *ep, struct dwc2_request *req)
>  	invalidate_dcache_range((unsigned long) ep->dma_buf,
>  				(unsigned long) ep->dma_buf + ep->len);
>  
> -	writel((unsigned int) ep->dma_buf, &reg->out_endp[ep_num].doepdma);
> +	/* ensure that ep->dma_buf fits into 32 bits */
> +	if (((uintptr_t)ep->dma_buf & 0xffffffff) != (uintptr_t)ep->dma_buf)
> +		error("ep->dma_buf does not fit into a 32 bits");

You print an error, but still continue with the function ? That'll
probably lead to a crash, you should rather abort. In fact, I suspect
you can use bounce-buffer to assure the dma buffer is in 32bit space.

> +	writel((uintptr_t)ep->dma_buf, &reg->out_endp[ep_num].doepdma);
>  	writel(DOEPT_SIZ_PKT_CNT(pktcnt) | DOEPT_SIZ_XFER_SIZE(length),
>  	       &reg->out_endp[ep_num].doeptsiz);
>  	writel(DEPCTL_EPENA|DEPCTL_CNAK|ctrl, &reg->out_endp[ep_num].doepctl);
> 


-- 
Best regards,
Marek Vasut