On Thu, Jan 13, 2022 at 03:35:14PM +0800, Jiri Slaby wrote: >> diff --git a/drivers/tty/serial/milbeaut_usio.c b/drivers/tty/serial/milbeaut_usio.c >> index 8f2cab7f66ad..1ecbf6d0dc79 100644 >> --- a/drivers/tty/serial/milbeaut_usio.c >> +++ b/drivers/tty/serial/milbeaut_usio.c >> @@ -523,6 +523,10 @@ static int mlb_usio_probe(struct platform_device *pdev) >> } >> port->membase = devm_ioremap(&pdev->dev, res->start, >> resource_size(res)); >> + if (!port->membase) { >> + ret = -ENOMEM; >> + goto failed; >> + } > > what about using devm_ioremap_resource() and have only one if there? Well, I check the comment of the devm_ioremap_resource() and notice that it checks and requests region before ioremap. And the usage example is fit for the situation. But I have still have no idea what the concrete advantages of the devm_ioremap_resource(), like fixing something or improve the efficiency. Please give me more detail. Sincerely thanks, Jiang