linux-kernel - Re: [PATCH v5 1/3] spi: airoha-snfi: en7523: workaround flash damaging if UART

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Message-ID: <5634e1ef-f843-4a30-9d78-7058ed2fe869@iopsys.eu>
Date: Wed, 26 Nov 2025 01:53:36 +0300
From: Mikhail Kshevetskiy <mikhail.kshevetskiy@...sys.eu>
To: Andy Shevchenko <andriy.shevchenko@...el.com>
Cc: Lorenzo Bianconi <lorenzo@...nel.org>, Ray Liu <ray.liu@...oha.com>,
 Mark Brown <broonie@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Matthias Brugger <matthias.bgg@...il.com>,
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
 Andy Shevchenko <andy@...nel.org>, linux-arm-kernel@...ts.infradead.org,
 linux-spi@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-mediatek@...ts.infradead.org,
 Andreas Gnau <andreas.gnau@...sys.eu>
Subject: Re: [PATCH v5 1/3] spi: airoha-snfi: en7523: workaround flash
 damaging if UART_TXD was short to GND


On 11/25/25 23:24, Andy Shevchenko wrote:
> On Tue, Nov 25, 2025 at 10:16:33PM +0300, Mikhail Kshevetskiy wrote:
>
> ...
>
>> +			dev_warn(dev, "Detected booting in RESERVED mode (UART_TXD was short to GND).\n");
>> +			dev_warn(dev, "This mode is known for incorrect DMA reading of some flashes.\n");
>> +			dev_warn(dev, "Usage of DMA for flash operations will be disabled to prevent data\n");
>> +			dev_warn(dev, "damage. Unplug your serial console and power cycle the board\n");
>> +			dev_warn(dev, "to boot with full performance.\n");
> One non-critical remark (for the future), the '\n' in the string literals when
> we print messages has two meanings:
>  - (obviously) new line
>  - (seems not so obvious for people) flush the line to the output device
>
> Due to the second property the messages might be interleaved with the other
> messages (assuming SMP machine actively doing and printing something), hence
> your messages might be split with other and imagine the user who gets in the
> middle of the text something like
>
> "Usage of DMA for flash operations will be disabled to prevent data"
>
> The first thought will be "what the heck does this mean?"
>
> TL;DR: place '\n' with a care in the messages to print not only here,
> but in general.

Thanks for the point. I know this '\n' issue, but you give me an idea
about making it better.

>