[U-Boot] [PATCH] imx: serial: Wait for ongoing transmission to finish before serial reset

[Simon Glass]

Hi Lucasz,

On 9 October 2017 at 12:46, Łukasz Majewski <lukma at denx.de> wrote:
> Hi Simon,
>
>> Hi Lukasz,
>>
>> On 3 October 2017 at 03:16, Lukasz Majewski <lukma at denx.de> wrote:
>>>
>>> It may happen that the MXC serial IP block is performing some ongoing
>>> transmission (started at e.g. board_init()) when the "initr_serial" is
>>> called.
>>>
>>> As a result the serial port IP block is reset, so transmitted data is
>>> corrupted:
>>>
>>> I2C:   ready
>>> DRAM:  1 GiB
>>> jSS('HH��SL_SDHC: 04 rev 0x0
>>>
>>> This patch prevents from this situation, by waiting for transmission
>>> complete bit set (UART Status Register 2 (UARTx_USR2), bit TXDC):
>>>
>>> I2C:   ready
>>> DRAM:  1 GiB
>>> ID:    unit type 0x4 rev 0x0
>>>
>>> Signed-off-by: Lukasz Majewski <lukma at denx.de>
>>> ---
>>>
>>>   drivers/serial/serial_mxc.c | 7 +++++++
>>>   1 file changed, 7 insertions(+)
>>
>>
>> Is it possible to use driver model to do this in a generic way for all
>> serial drivers? The pending() method allows you to check if there are
>> any characters in the output FIFO.
>
>
> Please correct me if I'm wrong.
>
> Do you mean to define pre_init() callback in serial-uclass.c file, which
> would utilize ->pending callback if available?
>
> In that way we would have the generic facility for above check available on
> all platforms.

Yes that is what I am hoping.

Regards,
Simon