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SubjectRe: [PATCH v3 3/4] tty/serial: meson_uart: add the core clock handling to the driver
On Mon, Apr 3, 2017 at 7:57 AM, Jerome Brunet <jbrunet@baylibre.com> wrote:
> On Fri, 2017-03-31 at 18:54 +0200, Helmut Klein wrote:
>> This patch gets the core clock as provided by the DT and enables it.
>> The code was taken from Amlogic's serial driver, and was tested on my
>> board.
>>
>> Signed-off-by: Helmut Klein <hgkr.klein@gmail.com>
>> ---
>> drivers/tty/serial/meson_uart.c | 10 ++++++++++
>> 1 file changed, 10 insertions(+)
>>
>> diff --git a/drivers/tty/serial/meson_uart.c b/drivers/tty/serial/meson_uart.c
>> index 60f16795d16b..cb99112288eb 100644
>> --- a/drivers/tty/serial/meson_uart.c
>> +++ b/drivers/tty/serial/meson_uart.c
>> @@ -600,6 +600,7 @@ static int meson_uart_probe(struct platform_device *pdev)
>> struct resource *res_mem, *res_irq;
>> struct uart_port *port;
>> struct clk *clk;
>> + struct clk *core_clk;
>> int ret = 0;
>>
>> if (pdev->dev.of_node)
>> @@ -625,6 +626,15 @@ static int meson_uart_probe(struct platform_device *pdev)
>> if (!port)
>> return -ENOMEM;
>>
>> + core_clk = devm_clk_get(&pdev->dev, "core");
>> + if (!IS_ERR(core_clk)) {
>> + ret = clk_prepare_enable(core_clk);
>
> This needs to be balanced with a clk_disable_unprepare() in remove.
>
> You could try play with devm_add_action_or_reset, maybe like this:
>
> devm_add_action_or_reset(dev,
> (void(*)(void *))clk_disable_unprepare,
> core_clk);
>
> Sorry I did not notice it on the v2.
>
>
>> + if (ret) {
>> + dev_err(&pdev->dev, "couldn't enable clkc\n");
>> + return ret;
>> + }
>> + }
>> +
>> clk = clk_get(&pdev->dev, NULL);
>
> I still think you should name this one. Otherwise, what the non AO UART will get
> here will depends on the order it was declared in DT.

Unfortunately, it has to be even a little more complicated.

This driver will need to work with current DT (no clock-names) as well
as newer DT using clock-names for "core" and "xtal". So, you'll have
to first try for "xtal" here, and if it fails, then try NULL.

> To answer your question from the v2, yes I think it is ok to add clock-names to
> the AO-UART. You are doing it for non AO ones so, why not ?

Agreed. And another good reason the driver needs to handle with and
without clock-names.

Kevin

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