[PATCH 14/20] serial_lpuart: add clock enable if CONFIG_CLK is defined

[Lukasz Majewski]

On Mon, 9 Dec 2019 16:20:10 +0100
Giulio Benetti <giulio.benetti at benettiengineering.com> wrote:

> Hi Lukasz,
> 
> On 12/8/19 3:52 PM, Lukasz Majewski wrote:
> > On Wed,  4 Dec 2019 18:44:33 +0100
> > Giulio Benetti <giulio.benetti at benettiengineering.com> wrote:
> >   
> >> This driver assumes that lpuart clock is already enabled before
> >> probing but using DM only lpuart won't be automatically enabled so
> >> add clk_enable() when probing if CONFIG_CLK is defined.
> >>
> >> Signed-off-by: Giulio Benetti
> >> <giulio.benetti at benettiengineering.com> ---
> >>   drivers/serial/serial_lpuart.c | 13 +++++++++++++
> >>   1 file changed, 13 insertions(+)
> >>
> >> diff --git a/drivers/serial/serial_lpuart.c
> >> b/drivers/serial/serial_lpuart.c index 4b0a964d1b..52bd2baf7d
> >> 100644 --- a/drivers/serial/serial_lpuart.c
> >> +++ b/drivers/serial/serial_lpuart.c
> >> @@ -483,6 +483,19 @@ static int lpuart_serial_pending(struct
> >> udevice *dev, bool input)
> >>   static int lpuart_serial_probe(struct udevice *dev)
> >>   {
> >> +#if CONFIG_IS_ENABLED(CLK)
> >> +	struct clk per_clk;
> >> +	int ret;
> >> +
> >> +	ret = clk_get_by_name(dev, "per", &per_clk);
> >> +	if (ret) {
> >> +		dev_err(dev, "Failed to get per clk: %d\n", ret);
> >> +		return ret;
> >> +	}
> >> +
> >> +	clk_enable(&per_clk);
> >> +#endif
> >> +  
> > 
> > I think that this change will _silently_ break all boards which do
> > have CONFIG_CLK enabled (for some clocks/drivers), but did not yet
> > provided CCF definition for lpuart clock.  
> 
> Oops, yes, you're totally right.
> Would it be correct if I try to retrieve clock and otherwise I
> fallback sending warnings like following?:
> 
> `
> static int lpuart_serial_probe(struct udevice *dev)
> {
> #if CONFIG_IS_ENABLED(CLK)
> 	struct clk per_clk;
> 	int ret;
> 
> 	ret = clk_get_by_name(dev, "per", &per_clk);
> 	if (!ret) {
> 		ret = clk_enable(&per_clk);
> 		if (ret) {
> 			dev_err(dev, "Failed to get per clk: %d\n",
> 				ret);
> 			return;
> 		}
> 	} else {
> 		dev_warn(dev, "Failed to get per clk: %d\n",
> 			 ret);
> 	}
> #endif
> 

Yes, warning is OK.

> ....
> 
> `
> 
> Best regards




Best regards,

Lukasz Majewski

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