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From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Francesco Lavra <flavra@baylibre.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jiri Slaby <jirislaby@kernel.org>,
	Kartik Rajput <kkartik@nvidia.com>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Wolfram Sang <wsa+renesas@sang-engineering.com>,
	Robert Marko <robert.marko@sartura.hr>,
	Thierry Bultel <thierry.bultel.yh@bp.renesas.com>,
	Douglas Anderson <dianders@chromium.org>,
	linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org
Subject: Re: [PATCH] serial: tegra: remove Kconfig dependency on APB DMA controller
Date: Wed, 26 Nov 2025 18:25:14 +0200	[thread overview]
Message-ID: <aScp6mooEKUkBkA6@smile.fi.intel.com> (raw)
In-Reply-To: <562c2b30820d083ff0b5e04ac176ed66c0064363.camel@baylibre.com>

On Wed, Nov 26, 2025 at 01:08:23PM +0100, Francesco Lavra wrote:
> On Wed, 2025-11-26 at 13:20 +0200, Andy Shevchenko wrote:
> > On Wed, Nov 26, 2025 at 10:07:59AM +0100, Francesco Lavra wrote:

...

> > >         help
> > >           Support for the on-chip UARTs on the NVIDIA Tegra series SOCs
> > >           providing /dev/ttyTHS0, 1, 2, 3 and 4 (note, some machines
> > > may not
> > >           provide all of these ports, depending on how the serial port
> > > -         are enabled). This driver uses the APB DMA to achieve higher
> > > baudrate
> > > -         and better performance.
> > > +         are enabled).
> > 
> > I think this removes a good piece of information. Perhaps rephrase?
> > 
> >           This driver may use the APB DMA when available to achieve
> >           higher baudrate and better performance.
> 
> I think this sentence would make it sound like the driver performs better
> if the APB DMA controller is available, but in reality the driver just uses
> the generic DMA API like most serial drivers, and there is nothing APB-
> specific in it. If another DMA controller (e.g. GPC on Tegra234) is
> available instead of the APB one, the serial peripheral will be just as
> fast.

OK. But this is not the case for Tegra234? Or is it and it uses DMA for UART?

-- 
With Best Regards,
Andy Shevchenko



  reply	other threads:[~2025-11-26 16:25 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-11-26  9:07 [PATCH] serial: tegra: remove Kconfig dependency on APB DMA controller Francesco Lavra
2025-11-26 11:20 ` Andy Shevchenko
2025-11-26 12:08   ` Francesco Lavra
2025-11-26 16:25     ` Andy Shevchenko [this message]
2025-11-26 16:45       ` Francesco Lavra
2025-11-26 17:44         ` Andy Shevchenko
2026-02-25 11:35 ` Francesco Lavra
2026-03-12 13:43   ` Greg Kroah-Hartman
2026-03-13  7:56     ` Francesco Lavra
2026-02-26 10:04 ` Jon Hunter

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