From: Stefan-gabriel Mirea <stefan-gabriel.mirea@nxp.com>
To: "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>
Cc: "mark.rutland@arm.com" <mark.rutland@arm.com>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"corbet@lwn.net" <corbet@lwn.net>,
"catalin.marinas@arm.com" <catalin.marinas@arm.com>,
"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
Larisa Ileana Grigore <larisa.grigore@nxp.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Leo Li <leoyang.li@nxp.com>,
Cosmin Stefan Stoica <cosmin.stoica@nxp.com>,
"robh+dt@kernel.org" <robh+dt@kernel.org>,
"linux-serial@vger.kernel.org" <linux-serial@vger.kernel.org>,
"jslaby@suse.com" <jslaby@suse.com>,
"shawnguo@kernel.org" <shawnguo@kernel.org>,
"will@kernel.org" <will@kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 5/6] tty: serial: Add linflexuart driver for S32V234
Date: Wed, 7 Aug 2019 16:42:17 +0000 [thread overview]
Message-ID: <VI1PR0402MB2863C4406C06B0BDA3581822DFD40@VI1PR0402MB2863.eurprd04.prod.outlook.com> (raw)
In-Reply-To: 20190806184042.GA26041@kroah.com
On 8/6/2019 9:40 PM, gregkh@linuxfoundation.org wrote:
> On Tue, Aug 06, 2019 at 05:11:17PM +0000, Stefan-gabriel Mirea wrote:
>> On 8/5/2019 6:31 PM, gregkh@linuxfoundation.org wrote:
>>> On Fri, Aug 02, 2019 at 07:47:23PM +0000, Stefan-gabriel Mirea wrote:
>>>>
>>>> +/* Freescale Linflex UART */
>>>> +#define PORT_LINFLEXUART 121
>>>
>>> Do you really need this modified?
>>
>> Hello Greg,
>>
>> This macro is meant to be assigned to port->type in the config_port
>> method from uart_ops, in order for verify_port to know if the received
>> serial_struct structure was really targeted for a LINFlex port. It
>> needs to be defined outside, to avoid "collisions" with other drivers.
>
> Yes, I know what it goes to, but does anyone in userspace actually use
> it?
No, we do not use it from userspace, but kept the pattern only for
conformance.
>> Other than that, I do not see anything wrong with the addition of a
>> define in serial_core.h for this purpose (which is also what most of the
>> serial drivers do, including amba-pl011.c, mentioned in
>> Documentation/driver-api/serial/driver.rst as providing the reference
>> implementation), so please be more specific.
>
> I am getting tired of dealing with merge issues with that list, and no
> one seems to be able to find where they are really needed for userspace,
> especially for new devices. What happens if you do not have use it?
I see. If I drop its usage completely and leave 'type' from the
uart_port as 0, uart_port_startup() will fail when finding that
uport->type == PORT_UNKNOWN at [1] (there may be other effects as well,
e.g. due to the check in uart_configure_port[2]).
So I suppose that I need to define some nonzero 'PORT_KNOWN' macro in
the driver and use that one internally for 'type'. Is my understanding
correct? Will there be any problems if I define it to a positive integer
which is already assigned to another driver, according to serial_core.h?
Regards,
Stefan
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/tty/serial/serial_core.c?h=v5.3-rc1#n188
[2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/tty/serial/serial_core.c?h=v5.3-rc1#n2348
next prev parent reply other threads:[~2019-08-07 16:42 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-02 19:47 [PATCH 0/6] Add initial support for S32V234-EVB Stefan-gabriel Mirea
2019-08-02 19:47 ` [PATCH 1/6] dt-bindings: arm: fsl: Add the S32V234-EVB board Stefan-gabriel Mirea
2019-08-02 22:38 ` Rob Herring
2019-08-03 8:00 ` [EXT] " Stefan-gabriel Mirea
2019-08-02 19:47 ` [PATCH 2/6] arm64: Introduce config for S32 Stefan-gabriel Mirea
2019-08-02 19:47 ` [PATCH 3/6] arm64: dts: fsl: Add device tree for S32V234-EVB Stefan-gabriel Mirea
2019-08-02 19:47 ` [PATCH 4/6] dt-bindings: serial: Document Freescale LINFlex UART Stefan-gabriel Mirea
2019-08-02 19:47 ` [PATCH 5/6] tty: serial: Add linflexuart driver for S32V234 Stefan-gabriel Mirea
2019-08-05 15:31 ` gregkh
2019-08-06 17:11 ` Stefan-gabriel Mirea
2019-08-06 18:40 ` gregkh
2019-08-07 16:42 ` Stefan-gabriel Mirea [this message]
2019-08-07 16:56 ` gregkh
2019-08-07 17:05 ` Stefan-gabriel Mirea
2019-08-08 8:08 ` Will Deacon
2019-08-08 12:47 ` Stefan-gabriel Mirea
2019-08-08 17:17 ` Will Deacon
2019-08-09 9:45 ` Stefan-gabriel Mirea
2019-08-09 9:53 ` Will Deacon
2019-08-09 9:57 ` Stefan-gabriel Mirea
2019-08-02 19:47 ` [PATCH 6/6] arm64: defconfig: Enable configs " Stefan-gabriel Mirea
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