Re: [PATCH v3.6.1] usb: serial: ftdi_sio: Add missingchars_in_buffer function

From: Alan Cox
Date: Wed Oct 10 2012 - 11:43:15 EST


On Wed, 10 Oct 2012 15:05:06 +0200
Jarkko Huijts <jarkko.huijts@xxxxxxxxxxxxxxxxx> wrote:

> From: Jarkko Huijts <jarkko.huijts@xxxxxxxxx>
>
> The driver does not wait until the hardware buffer (for data from the PC to the
> UART line) is drained when tcdrain or close is called in an application.
> Solution: Implement a chars_in_buffer function that checks both the software
> and hardware buffer. If the TEMT (TX empty) bit of the line status register
> indicates the hw buffer is not empty, let the function return at least 1. This
> has been verified to work correctly with an FT232RL. The check on the hw buffer
> can not be done for the original SIO device.
>
> Signed-off-by: Jarkko Huijts <jarkko.huijts@xxxxxxxxx>

Acked-by: Alan Cox <alan@xxxxxxxxxxxxxxx>
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