Re: [PATCH v6 5/6] usb:cdns3 Add Cadence USB3 DRD Driver

[Sekhar Nori]

On 10/04/19 1:18 PM, Pawel Laszczak wrote:
> +static void cdns3_wa1_tray_restore_cycle_bit(struct cdns3_device *priv_dev,
> +                                          struct cdns3_endpoint *priv_ep)
> +{
> +     int dma_index;
> +     u32 doorbell;
> +
> +     doorbell = !!(readl(&priv_dev->regs->ep_cmd) & EP_CMD_DRDY);

> +     dma_index = (readl(&priv_dev->regs->ep_traddr) -
> +                 priv_ep->trb_pool_dma) / TRB_SIZE;

This gets upgraded to 64-bit by 64-bit division whenever dma_addr_t is 
64-bit. That should be avoided. Following diff should fix it. 
But please review the logic itself. You are subtracting a 64 bit entity 
from a 32-bit entity. What is guaranteeing that priv_ep->trb_pool_dma is 
32-bit?

There is one more instance of same issue in cdns3_request_handled().

Thanks,
Sekhar

[1]
diff --git a/drivers/usb/cdns3/gadget.c b/drivers/usb/cdns3/gadget.c
index bfd5dbf40c7e..e73b618501fb 100644
--- a/drivers/usb/cdns3/gadget.c
+++ b/drivers/usb/cdns3/gadget.c
@@ -749,8 +749,8 @@ static void cdns3_wa1_tray_restore_cycle_bit(struct 
cdns3_device *priv_dev,
        u32 doorbell;
 
        doorbell = !!(readl(&priv_dev->regs->ep_cmd) & EP_CMD_DRDY);
-       dma_index = (readl(&priv_dev->regs->ep_traddr) -
-                   priv_ep->trb_pool_dma) / TRB_SIZE;
+       dma_index = readl(&priv_dev->regs->ep_traddr) - priv_ep->trb_pool_dma;
+       dma_index /= TRB_SIZE;