linux-kernel - Re: [PATCH v1 0/1] Mediatek uart patch

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Message-ID: <YQJEzlb2NyxD1EpD@kroah.com>
Date:   Thu, 29 Jul 2021 08:03:58 +0200
From:   Greg KH <greg@...ah.com>
To:     Zhiyong Tao <zhiyong.tao@...iatek.com>
Cc:     timur@...nel.org, linux@...linux.org.uk, alcooperx@...il.com,
        tklauser@...tanz.ch, sean.wang@...nel.org,
        srv_heupstream@...iatek.com, hui.liu@...iatek.com,
        yuchen.huang@...iatek.com, huihui.wang@...iatek.com,
        eddie.huang@...iatek.com, sean.wang@...iatek.com,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-serial@...r.kernel.org
Subject: Re: [PATCH v1 0/1] Mediatek uart patch

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