Question regarding ns16550

[Daniel Gutson]

On Fri, Oct 24, 2014 at 2:33 AM, Sebastian Huber
<sebastian.huber at embedded-brains.de> wrote:
> On 23/10/14 18:12, Daniel Gutson wrote:
>>
>> On Thu, Oct 23, 2014 at 5:47 AM, Sebastian Huber
>> <sebastian.huber at embedded-brains.de>  wrote:
>>>
>>> >Hello Daniel,
>>
>> Hi Sebastian,
>>
>>> >
>>> >I never notice a problem with this driver.  It should only write to the
>>> > FIFO
>>> >in case it is completely empty.  Did you observe problems?
>>
>> no, I didn't (actually I found this while looking for a serial bug
>> which turned out to be due
>> to a different cause).
>> However, I notice that this isn't like what the polling write does (of
>> course I'm not talking
>> about the polling/interrput difference, but when writing byte-per-byte
>> to the FIFO, I think
>> both methods should do the same).
>> IOW, what happens if the 'for' loop is too fast for the device? Will
>> the latter be able to
>> put the char in the FIFO and be ready for the next one? Isn't
>> SP_LSR_THOLD exactly
>> to tell whether the device' FIFO is ready to accept the next byte?
>> Writing to the FIFO when it's completely empty is not the problem I
>> see since it is
>> guaranteed by the interrupt. My concern is different: it's whether the
>> FIFO is filled too fast
>> for the device.
>>
>>
>
> Its not clear to me from the documentation if this is really necessary.  I
> never noticed problems on several targets with this driver.

Ok.

>
>
> --
> Sebastian Huber, embedded brains GmbH
>
> Address : Dornierstr. 4, D-82178 Puchheim, Germany
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>
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-- 

Daniel F. Gutson
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