From: swarren@wwwdotorg•org (Stephen Warren)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 3/4] serial: bcm2835: add auxiliary uart1 to device tree of bcm2835
Date: Wed, 23 Sep 2015 09:18:53 -0600 [thread overview]
Message-ID: <5602C2DD.20805@wwwdotorg.org> (raw)
In-Reply-To: <5602788E.3070103@martin.sperl.org>
On 09/23/2015 04:01 AM, Martin Sperl wrote:
> On 22.09.2015 04:42, Stephen Warren wrote:
>> On 09/11/2015 05:20 AM, kernel at martin.sperl.org wrote:
>>> From: Martin Sperl <kernel@martin•sperl.org>
>>>
>>> Add the auxiliary uart1 device to the device tree of the bcm2835 SOC.
>>
>>> diff --git a/arch/arm/boot/dts/bcm2835.dtsi
>>> b/arch/arm/boot/dts/bcm2835.dtsi
>>
>>> + uart1: uart at 7e215040 {
>>> + compatible = "ns16550";
>>
>> compatible should always include a precise HW-specific value; something
>> like brcm,bcm2835-aux-uart. That way, if we find some other issue that
>> needs working around on this HW in the future, all DTs will already
>> contain the compatible value that SW needs in order to trigger that
>> workaround. That's a generally true statement; i.e. irrespective of
>> anything else in this series.
>>
>> I don't believe "ns16550" should be in the compatible value for this
>> device, since the device cannot be successfully driven by SW that only
>> knows about a standard 16650 UART. SW must know about the different
>> divider, and there is no possibility of SW knowing about that before
>> this series.
>>
>
> OK - I will look into creating a separate driver then that uses the 8250
> implementation as a basis...
I expect all you need to do is add a new PORT_* value to the existing
driver (which then drives some new quirk setting re: the clock rate),
and add new entry for the compatible value in of_platform_serial_table[]
in drivers/tty/serial/of_serial.c to select the correct TYPE_*.
next prev parent reply other threads:[~2015-09-23 15:18 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-11 12:20 [PATCH 0/4] bcm2835: enable auxiliary uart1 kernel at martin.sperl.org
2015-09-11 12:20 ` [PATCH 1/4] serial: of-serial: allow for a custom clock divider different from 16 kernel at martin.sperl.org
2015-09-11 12:20 ` [PATCH 2/4] dt/bindings: serial: of-serial: add description for clock-divider property kernel at martin.sperl.org
2015-09-11 12:20 ` [PATCH 3/4] serial: bcm2835: add auxiliary uart1 to device tree of bcm2835 kernel at martin.sperl.org
2015-09-22 2:42 ` Stephen Warren
2015-09-23 10:01 ` Martin Sperl
2015-09-23 15:18 ` Stephen Warren [this message]
2015-09-11 12:20 ` [PATCH 4/4] ARM: bcm2835: add of-serial and 8250 to bcm2835_defconfig kernel at martin.sperl.org
2015-09-14 14:53 ` [PATCH 0/4] bcm2835: enable auxiliary uart1 Eric Anholt
2015-09-22 2:39 ` Stephen Warren
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