From: Mitch Bradley <wmb@firmworks.com>
To: Stephen Warren <swarren@wwwdotorg.org>
Cc: Laxman Dewangan <ldewangan@nvidia.com>,
grant.likely@secretlab.ca, rob.herring@calxeda.com,
linux-doc@vger.kernel.org, gregkh@linuxfoundation.org,
devicetree-discuss@lists.ozlabs.org,
linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org,
linux-tegra@vger.kernel.org, jslaby@suse.cz,
alan@linux.intel.com
Subject: Re: [PATCH] serial: tegra: add serial driver
Date: Mon, 17 Dec 2012 11:58:24 -1000 [thread overview]
Message-ID: <50CF9580.4050300@firmworks.com> (raw)
In-Reply-To: <50CF9043.8030308@wwwdotorg.org>
On 12/17/2012 11:36 AM, Stephen Warren wrote:
> On 12/17/2012 05:10 AM, Laxman Dewangan wrote:
>> Nvidia's Tegra has multiple uart controller which supports:
>> - APB dma based controller fifo read/write.
>> - End Of Data interrupt in incoming data to know whether end
>> of frame achieve or not.
>> - Hw controlled RTS and CTS flow control to reduce SW overhead.
>
>> diff --git a/Documentation/devicetree/bindings/serial/nvidia,serial-tegra.txt b/Documentation/devicetree/bindings/serial/nvidia,serial-tegra.txt
>
>> +NVIDIA Tegra20/Tegra30 high speed (dma based) UART controller driver.
>> +
>> +Required properties:
>> +- compatible : should be "nvidia,tegra20-hsuart", "nvidia,tegra30-hsuart".
>
> One question that isn't addressed here is:
>
> Tegra has 5 UARTs. All of them can use the existing 8250.c by specifying
> compatible = "nvidia,tegra20-uart".
The way it is supposed to work is that the compatible property should
list "nvidia,tegra30-hsuart" first, followed by a fallback name that
refers to the generic 8250 compatibility. Having the 8250.c driver bind
to the more-specific tegra30-hsuart name is wrong.
However, the 8250.c driver doesn't
> support the DMA features of this driver. This driver is an alternate
> driver for the same HW that allows DMA to be used with it, etc.
>
> Since DT is supposed to describe the HW, modifying the DT to change the
> compatible value in order to select a different driver in Linux doesn't
> seem correct, or is it? Is there any kind of precedent for how to select
> different drivers for the same HW at run-time? I'd wondered about using
> the sysfs bind/unbind "methods" from user-space as the driver selection
> mechanism...
> _______________________________________________
> devicetree-discuss mailing list
> devicetree-discuss@lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/devicetree-discuss
>
next prev parent reply other threads:[~2012-12-17 21:59 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-17 12:10 [PATCH] serial: tegra: add serial driver Laxman Dewangan
2012-12-17 15:13 ` Greg KH
2012-12-17 15:24 ` Rob Herring
2012-12-17 21:30 ` Stephen Warren
2012-12-17 17:10 ` Grant Likely
2012-12-17 21:31 ` Stephen Warren
2012-12-19 13:01 ` Grant Likely
2012-12-19 14:15 ` Laxman Dewangan
2012-12-19 16:58 ` Stephen Warren
2012-12-20 1:09 ` Grant Likely
2012-12-17 18:23 ` Alan Cox
2012-12-17 21:36 ` Stephen Warren
2012-12-17 21:58 ` Mitch Bradley [this message]
2012-12-17 22:04 ` Stephen Warren
2012-12-17 22:17 ` Mitch Bradley
2012-12-19 13:03 ` Grant Likely
2012-12-17 21:55 ` Stephen Warren
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