From mboxrd@z Thu Jan 1 00:00:00 1970 From: robert.jarzmik@free.fr (Robert Jarzmik) Date: Tue, 22 Dec 2015 20:27:05 +0100 Subject: [PATCH v4 1/2] serial: rewrite pxa2xx-uart to use 8250_core In-Reply-To: <1450610665.15911.53.camel@gmail.com> (Sergei Ianovich's message of "Sun, 20 Dec 2015 14:24:25 +0300") References: <1387309071-22382-1-git-send-email-ynvich@gmail.com> <1449700088-28076-1-git-send-email-ynvich@gmail.com> <1449700088-28076-2-git-send-email-ynvich@gmail.com> <8737uyhaji.fsf@belgarion.home> <87y4cqfu2j.fsf@belgarion.home> <1450550792.15911.5.camel@gmail.com> <87twnefd67.fsf@belgarion.home> <1450555955.15911.14.camel@gmail.com> <87poy2f2xw.fsf@belgarion.home> <1450610665.15911.53.camel@gmail.com> Message-ID: <87a8p2ffna.fsf@belgarion.home> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Sergei Ianovich writes: > On Sun, 2015-12-20 at 00:12 +0100, Robert Jarzmik wrote: >> Sergei Ianovich writes: >> >> > On Sat, 2015-12-19 at 20:31 +0100, Robert Jarzmik wrote: >> > I understand that people are afraid of taking this patch. If it >> > starts >> > causing troubles at runtime, it will be difficult to diagnose. There >> > will be no console for most people. So it is probably good idea to >> > fail >> > at boot time. >> If it's about something already written in a mailing >> list, please point me to it so that it can help me think about it. > > http://lists.infradead.org/pipermail/linux-arm-kernel/2013-December/2167 > 73.html > > I can explain why I think so. Greg acked the patch, but hasn't merged it > since then. He has good reasons for this most probably. Russell's > comment pointed by the link seems to be the reason. > I think the problem raised by Russell could be addressed. My best guess > is compile time error, despite your comment above. I re-read carefully Russell's answer in [1]. What Russell asked is that for a period of time, the old pxa serial code and the new will be in the kernel, so that maintainers have the option to switch over to the old drivers/tty/serial/pxa.c if the new 8250 based version breaks their userspace getty. Then, once the transition is done, and that for a period (let's say 1 year) no maintainer had complained while its defconfig was switched over to the new 8520 version, then and only then you will remove drivers/tty/serial/pxa.c. > I have one more plan. For transition period, we can introduce a > temporary Kconfig option SERIAL_8250_PXA_OFF, and fail at build time if > neither SERIAL_8250_PXA nor SERIAL_8250_PXA_OFF is set. This way all > interested parties will be notified of this driver update. No, I'd like to stick with Russell's original plan : - phase 1: both SERIAL_8250_PXA and SERIAL_PXA exist in KConfig both are selectable This lasts one year or something like that - phase 2: remove SERIAL_PXA from KConfig and drivers/tty/serial/pxa.c This means a different patch from the one acked by Greg, and a new serie of acks. The diffstat will be way worse (as you won't have the -970 for pxa.c), but in the end it will end up on that -970. That sounds like a good transition plan to me. Cheers. -- Robert [1] http://lists.infradead.org/pipermail/linux-arm-kernel/2013-December/216773.html