linux-kernel - Re: [PATCH] tty/serial: at91: restore dynamic driver binding

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Date:	Wed, 24 Feb 2016 15:09:49 +0100
From:	Romain Izard <romain.izard.pro@...il.com>
To:	Paul Gortmaker <paul.gortmaker@...driver.com>
Cc:	linux-serial@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Nicolas Ferre <nicolas.ferre@...el.com>,
	LKML <linux-kernel@...r.kernel.org>, Jiri Slaby <jslaby@...e.com>
Subject: Re: [PATCH] tty/serial: at91: restore dynamic driver binding

2016-02-23 20:18 GMT+01:00 Paul Gortmaker <paul.gortmaker@...driver.com>:
> [[PATCH] tty/serial: at91: restore dynamic driver binding] On 23/02/2016 (Tue 17:59) Romain Izard wrote:
>
>> In commit c39dfebc7798956fd2140ae6321786ff35da30c3, the modular support
>> code for atmel_serial was removed, as the driver cannot be built as a
>> module. Because no use case was proposed, the dynamic driver binding
>> support was removed as well.
>>
>> The atmel_serial driver can manage up to 7 serial controllers, which are
>> multiplexed with other functions. For example, in the Atmel SAMA5D2, the
>> Flexcom controllers can work as USART, SPI or I2C controllers, and on
>> all Atmel devices serial lines can be reconfigured as GPIOs.
>>
>> My use case uses GPIOs to transfer a firmware update using a custom
>> protocol on the lines used as a serial port during the normal life of
>> the device. If it is not possible to unbind the atmel_serial driver, the
>> GPIO lines remain reserved and prevent this case from working.
>>
>> This patch reinstates the atmel_serial_remove function, and fixes it as
>> it failed to clear the "clk" field on removal, triggering an oops when
>> a device was bound again after being unbound.
>
> I'd suggest that you add a comment above the remove fcn that gives the
> executive summary of the above; i.e. an unbind allows a fw update via
> blah blah and hence the .remove makes sense even though the driver is
> not modular.
>
OK, I'll send a v2.


Best regards,