usb: gadget: aspeed_udc: fix handling of tx_len == 0

The bug is that we should still enter this loop if "tx_len" is zero.

After adding the "last" variable, then the "chunk >= 0" condition is no
longer required but I left it for readability.

Fixes: c09b1f372e74 ("usb: gadget: aspeed_udc: cleanup loop in ast_dma_descriptor_setup()")
Reported-by: Neal Liu <neal_liu@aspeedtech.com>
Reviewed-by: Neal Liu <neal_liu@aspeedtech.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/Yrq6F5okoX1y05rT@kili
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/gadget/udc/aspeed_udc.c b/drivers/usb/gadget/udc/aspeed_udc.c
index d75a4e0..01968e2 100644 (file)
--- a/drivers/usb/gadget/udc/aspeed_udc.c
+++ b/drivers/usb/gadget/udc/aspeed_udc.c
@@ -476,6 +476,7 @@ static int ast_dma_descriptor_setup(struct ast_udc_ep *ep, u32 dma_buf,
 {
        struct ast_udc_dev *udc = ep->udc;
        struct device *dev = &udc->pdev->dev;
+       bool last = false;
        int chunk, count;
        u32 offset;
 
@@ -493,14 +494,16 @@ static int ast_dma_descriptor_setup(struct ast_udc_ep *ep, u32 dma_buf,
               "tx_len", tx_len);
 
        /* Create Descriptor Lists */
-       while (chunk > 0 && count < AST_UDC_DESCS_COUNT) {
+       while (chunk >= 0 && !last && count < AST_UDC_DESCS_COUNT) {
 
                ep->descs[ep->descs_wptr].des_0 = dma_buf + offset;
 
-               if (chunk > ep->chunk_max)
+               if (chunk > ep->chunk_max) {
                        ep->descs[ep->descs_wptr].des_1 = ep->chunk_max;
-               else
+               } else {
                        ep->descs[ep->descs_wptr].des_1 = chunk;
+                       last = true;
+               }
 
                chunk -= ep->chunk_max;