Re: [PATCH] serial: 8250_dw: retain programmed timing for BUSY waits

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Mon, Oct 12, 2026 at 06:10:20AM -0000, khaliforce wrote:
> Baud changes update frame_time before the programmed divisor changes.
> A switch to a faster baud rate therefore shortens the DesignWare BUSY
> wait.
> The wait can expire while a frame at the old baud rate remains active.
> 
> Use the programmed frame duration for FIFO and BUSY waits.
> Account for UART clock changes.
> 
> Fixes: a7b9ce39fbe4 ("serial: 8250_dw: Ensure BUSY is deasserted")
> Signed-off-by: khaliforce <kforce@gmail.com>
> ---
> Compared the complete patch off/on on MangoPi MQ Pro UART0.
> Kept other port patches, kernel options and DTB identical.
> Tested BUSY changes from 9600, 1200 and 300 to 115200.
> All 11 paired changes fail without the patch and pass with it.
> Each trial returns 64 matching loopback bytes.

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
a patch that has triggered this response.  He used to manually respond
to these common problems, but in order to save his sanity (he kept
writing the same thing over and over, yet to different people), I was
created.  Hopefully you will not take offence and will fix the problem
in your patch and resubmit it so that it can be accepted into the Linux
kernel tree.

You are receiving this message because of the following common error(s)
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  Documentation/process/submitting-patches.rst for how to do this
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If you wish to discuss this problem further, or you have questions about
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thanks,

greg k-h's patch email bot