On Thu, 2021-07-29 at 08:03 +0200, Greg KH wrote:

On Thu, Jul 29, 2021 at 09:48:16AM +0800, Zhiyong Tao wrote:

quoted

This series includes 1 patches:
1.fix uart corruption issue when rx power off

when uart is used as a communication port with external
device(GPS).
when external device(GPS) power off, the power of rx pin is also
from
1.8v to 0v. Even if there is not any data in rx. But uart rx pin
can
capture the data "0".
If uart don't receive any data in specified cycle, uart will
generates
BI(Break interrupt) interrupt.
If external device(GPS) power off, we found that BI interrupt
appeared
continuously and very frequently.
When uart interrupt type is BI, uart IRQ handler(8250 framwork
API:serial8250_handle_irq) will push data to tty buffer.
The code path:

https://elixir.bootlin.com/linux/latest/source/drivers/tty/serial/8250/8250_port.c#L1917

quoted

mtk8250_dma_rx_complete is a task of mtk_uart_apdma_rx_handler.
mtk8250_dma_rx_complete priority is lower than uart irq
handler(serial8250_handle_irq).
if we are in process of mtk8250_dma_rx_complete, uart appear BI
interrupt:1)serial8250_handle_irq will priority execution.2)it may
cause
write tty buffer conflict in mtk8250_dma_rx_complete.
So the spin lock protect the rx receive data process is not break.

All of this information should be in the changelog for the patch
itself.
There is no need for a "cover letter" for a single patch like this.

Can you redo your 1/1 patch and add the above information to the
changelog text and resend it as a v2?

thanks,

greg k-h

Dear greg,

Thanks for your suggestion. we will move it to patch 1/1 in v2.

Thanks.
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