[U-Boot] [PATCH 03/11] serial: atmel_usart: Use fixed clock value in SPL version

[Stefan Roese]

On 20.03.19 08:25, Eugen.Hristev at microchip.com wrote:
> 
> 
> On 19.03.2019 17:56, Stefan Roese wrote:
>> External E-Mail
>>
>>
>> This patch adds an alterative SPL version of atmel_serial_enable_clk().
>> This enables the usage of this driver without full clock support (in
>> drivers and DT nodes). This saves some space in the SPL image.
>>
>> If some boards need a different clock than the one provided with this
>> patch, then support for this needs to be added later.
>>
>> Signed-off-by: Stefan Roese <sr at denx.de>
>> Cc: Heiko Schocher <hs at denx.de>
>> Cc: Andreas Bießmann <andreas at biessmann.org>
>> Cc: Eugen Hristev <eugen.hristev at microchip.com>
>> ---
>>    drivers/serial/atmel_usart.c | 12 ++++++++++++
>>    1 file changed, 12 insertions(+)
>>
>> diff --git a/drivers/serial/atmel_usart.c b/drivers/serial/atmel_usart.c
>> index aa8cdff840..049172baef 100644
>> --- a/drivers/serial/atmel_usart.c
>> +++ b/drivers/serial/atmel_usart.c
>> @@ -218,6 +218,17 @@ static const struct dm_serial_ops atmel_serial_ops = {
>>    	.setbrg = atmel_serial_setbrg,
>>    };
>>    
>> +#ifdef CONFIG_SPL_BUILD
>> +static int atmel_serial_enable_clk(struct udevice *dev)
>> +{
>> +	struct atmel_serial_priv *priv = dev_get_priv(dev);
>> +
>> +	/* Use fixed clock value in SPL */
>> +	priv->usart_clk_rate = 132096000;
> 
> Hi Stefan,
> 
> Does this mean that the SPL will work *if and only if* this clock
> matches the board's clock, for all at91 boards? (thus, boards having a
> different clock , the serial will not function correctly anymore ?)

Yes, thats the case (as explained in the commit message above). For
this to work on all boards we need to add some macro like
CONFIG_DEBUG_UART_CLOCK which can be set by each board port
individually.

If agreed on such an idea, I can add this new Kconfig option in a
later version of this patch. Perhaps something like
CONFIG_SPL_UART_CLOCK?

Thanks,
Stefan