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
next prev parent 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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