[U-Boot] Rx FIFO: more than 64 bytes receive error

[Albert ARIBAUD]

Hi lokesh,

On Sat, 29 Dec 2012 17:01:35 +0530, lokesh nijalinge
<lokesh1kumar2nijalinge at gmail.com> wrote:
> Hi,
> 
> I am using the arm processor for my project and need to receive around 1K
> bytes of data over UART. I am able to receive only 64 bytes at U-boot,
> which is the UART RX FIFO size. After receiving the 64 bytes i am not
> getting any data. I read the Technical Reference Manual, which says the if
> more than FIFO size data is received then data will be lost instead
> of overwriting.
> 
> Please let me know whether i need to configure any UART registers to
> achieve more than 64 bytes.

> *Details of the project:*
> Processor : DM3730 from Texas instruments -OMAP3 ARM Cortex
> UART device : NS16550
> 
> The default code having the UART initialization sequence posted below does
> not seem to take care of the handling of more than 64 bytes of RX data.

Hmm... I can tell any U-Boot receives and correctly processes a lot more
than 64 bytes without any issue; I routinely throw a lot more than this
at the few U-Boot's I have lying around, all of which use NS16550-like
serials. I even sometimes 'loads' a payload of several hundred bytes to
some megs, without any issue.

However, while 'loads' itself can handle very large serial input, the
serial driver in itself will never handle more than the FIFO depth:
the 'loads' command handler has to read from the driver frequently in
order to avoid an overload.

In your case, you did not describe (or did I miss it?) what it is that
*uses* the received bytes, and how and when these received bytes are
read from the driver. Can you elaborate on this?

> *Changes done by us to get the Data from RX fifo. *

Please show such changes as a patch (made with got format-patch or at
least git diff) -- with '[RFC]' in the message subject so that we know
it is not a submission for inclusion into U-boot.

Amicalement,
-- 
Albert.