linux-kernel - Re: [PATCH 0/4] dmaengine: dw: Fix src/dst addr width misconfig

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Message-ID: <mrwbfrfzwklavzdaups633wtnen3fyvrpmmdrrcvvsxz3tsjaw@xxvvbycjgbuy>
Date: Wed, 17 Apr 2024 20:34:31 +0300
From: Serge Semin <fancer.lancer@...il.com>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: Viresh Kumar <vireshk@...nel.org>, Vinod Koul <vkoul@...nel.org>, 
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
	Jiri Slaby <jirislaby@...nel.org>, dmaengine@...r.kernel.org, linux-serial@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/4] dmaengine: dw: Fix src/dst addr width misconfig

On Tue, Apr 16, 2024 at 10:13:23PM +0300, Andy Shevchenko wrote:
> On Tue, Apr 16, 2024 at 07:28:54PM +0300, Serge Semin wrote:
> > The main goal of this series is to fix the data disappearance in case of
> > the DW UART handled by the DW AHB DMA engine. The problem happens on a
> > portion of the data received when the pre-initialized DEV_TO_MEM
> > DMA-transfer is paused and then disabled. The data just hangs up in the
> > DMA-engine FIFO and isn't flushed out to the memory on the DMA-channel
> > suspension (see the second commit log for details). On a way to find the
> > denoted problem fix it was discovered that the driver doesn't verify the
> > peripheral device address width specified by a client driver, which in its
> > turn if unsupported or undefined value passed may cause DMA-transfer being
> > misconfigured. It's fixed in the first patch of the series.
> > 
> > In addition to that two cleanup patch follow the fixes described above in
> > order to make the DWC-engine configuration procedure more coherent. First
> > one simplifies the CTL_LO register setup methods. Second one simplifies
> > the max-burst calculation procedure and unifies it with the rest of the
> > verification methods. Please see the patches log for more details.
> 
> Thank you for this.

> I have looked into all of them and most worrying (relatively to the rest) to me
> is the second patch that does some tricks.

That's a crucial patch for which the series has been intended. The
rest of the patches were created to align the code around the fix.

> The rest are the cosmetics that can
> be easily addressed.

Right. I'll have a look at the rest of your comments shortly.

-Serge(y)

> 
> -- 
> With Best Regards,
> Andy Shevchenko
> 
>