diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
index 36144f88d718..6a483eac7b3f 100644
--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -1216,7 +1216,7 @@ static int __init at_dma_probe(struct platform_device *pdev)
 	atdma->dma_common.cap_mask = pdata->cap_mask;
 	atdma->all_chan_mask = (1 << pdata->nr_channels) - 1;
 
-	size = io->end - io->start + 1;
+	size = resource_size(io);
 	if (!request_mem_region(io->start, size, pdev->dev.driver->name)) {
 		err = -EBUSY;
 		goto err_kfree;
@@ -1362,7 +1362,7 @@ static int __exit at_dma_remove(struct platform_device *pdev)
 	atdma->regs = NULL;
 
 	io = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	release_mem_region(io->start, io->end - io->start + 1);
+	release_mem_region(io->start, resource_size(io));
 
 	kfree(atdma);